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Thread: Guide to DSLR photography for Newbies + Product/Price/Outlet List

  1. #21
    Senior Member zoossh's Avatar
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    Default Re: DSLR newbie guide + Product/Price/Outlet List

    After getting your DSLR: Improving


    IMPROVING: 19. How to improve further?

    1. Get focused on what you like
    2. Reading books
    3. Practice more
    4. Post pictures and get feedbacks (as mentioned earlier)
    5. Take lessons if you want.
    6. Learn post processing



    IMPROVING: 20. Finding an area of interest

    Picking something you like is important as you can focus more on the techniques specific to that field, usually based on the subject, its lighting and its size/speed. You can then invest accordingly in necessary equipments for that field. Field that you can go into are not exhaustive but includes

    Setting a direction: quoted from Olivier Follmi

    You must first learn about who you are to find out what type of photographer you will be and how you look at things. Are you an outgoing person or more introverted? Do you like nature, the sea, the mountains, the desert, the jungle, cold or hot weather? Do you see life in close-up? Do you collect portraits from magazines? Do you dream of travelling? Are you captivated by war stories? Do you have a fascination for sporting events? Do you spend time at modern art exhibitions?

    By asking yourself this type of question you’ll be able to work out what sort of photographer you are and avoid going into a field where you will be unable to give of your best.



    - by specialised equipments & techniques, discussion on
    underwater photography, IR/UV photography, night photography, lomography

    Salon Photography: An approach that fosters craftsmanship and classic rules to things like composition and color and often subject. It is closer to "fine art" photography than to photography as an Art because rules in the later can change. (Quoted from Pico Digoliardi). Basically, people would submit their prints for judging and display to salons all over the world and ... more people would judge the entries and choose what would be displayed. (Quoted from Randall Ellis). The 1/3 rule, good contrast in color, textures and form; illumination, the right time of the day, nature of subject matter and crystal clarity of images taken - all these factors were a MUST elements before a clear consideration of a "good" photograph.... In short, Salon is about the golden rules, contrasts, compositions and well titled - that what everybody says. (Quoted from Leonard Foo)

    Salon Photography in Southeast Asia (by Leonard Foo)
    Salon Photographic competition in Europe versus the States (by Chris Hinterobermaier)

    The following is quoted from Mr. T. O. Lee

    "In Hong Kong, hobbyist photography can be broadly classified into two main categories: the salon photography and the contemporary fine arts photography, mainly differentiated by their styles.

    Salon photography focuses on the basics, such as the golden rules, the rule of one third (proportion of water or land against the skyline), contrasts created by colours, textures, lighting and the nature of the subject matter. Composition and technical skills are important elements. Photographers put much emphasis on beauty and atmosphere. And a title is very important to tell the viewers the intention of the photographers.

    The contemporary fine arts photography does not wish to follow the style of the salon photography. It goes along with the contemporary trend in the international fine arts development and tries to make some personal breakthroughs for self-expressions, through experimental exercises. Some of them make use of other media for presentation of their works. Creativity and originality are the important elements. Some photographers even don't mind that members of the public do not understand their works. The participants are mainly visual artists, designers, art directors, design school students and lovers of visual arts, including advertising photographers and professionals.

    Naturally they do not see beauty and atmosphere as the prime elements, and do not care too much about the golden rules, contrasts and composition. A title is not important. Most photographs are entitled "Untitled". They do not wish to influence the viewers and block their imagination with a title. They belief that different viewers of different cultural background and perception should be allowed to interact freely with the images to make their own interpretation, which is entirely personal. Hence they strongly object the common practice of some salon photographers to add Chinese poetic verses, water brush paintings and personal seals onto their works to imitate the ancient Chinese hand paintings scrolls. To them they don't look too natural."




    IMPROVING: 21. Where else should a newbie start reading?
    - READ THE STICKIES, so that the moderators and various forumers effort are not put to waste

    Start saucing your interest with books and magazines. Go to page 1, point 6 Useful reading

    .
    Last edited by zoossh; 25th November 2007 at 12:49 AM.

  2. #22
    Senior Member zoossh's Avatar
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    Default Re: DSLR newbie guide + Product/Price/Outlet List

    After getting your DSLR: Improving


    IMPROVING: 22. Where to practice?

    START SHOOTING, join the outing columns. so many outing should have serve various communities from azure's AG (anything goes), newbies, Buddhist, senior people (>50yrs old), Filipinos, bikers, girls, weirdos (just kidding). or scroll to the last posting update for upcoming events. of cos there is ppl like me who dun join outing but shoots travel photography.

    check out
    1. the last update for the list of city and landscape venues or
    2. g-khoo's first post for portraiture locations, or
    3. redstone's list and
    4. mich's haunted list

    if you wish to join fellow forumers living in the same area, there are user groups based on locations.
    North: Woodland, Sembawang, Yishun, AMK, Bishan
    East: Pasir Ris, Tampines, Bedok, Serangoon (1), (2), Sengkang
    Central: Chinatown, Tiong Bahru
    West: West, Upper Bukit Timah, Jurong
    Institutions: NUS, NTU, Singapore Poly, SIM, JC/MI

    here's a reading for those starting out by Ken Rockwell on How to make great photographs?



    IMPROVING: 23. Take lessons
    - take on lessons if you wish
    - search for SLCC and Photographic Society of Singapore(PSS) who conduct lessons.
    - occasional offers to help from fellow forumers, but this is not on a routine basis, keep a watchout. A recent one is over here (chngpe01, 2007 Apr 10).
    - others include SAFRA photoclub, photo vivo, Substation and Objectifs



    IMPROVING: 24. Post processing
    - complete your photographic experience by learning on post-processing techniques, e.g. this link.
    - get books relevant to your software, e.g. adobe lightroom/elements/photoshop or others.

    .
    Last edited by zoossh; 26th September 2008 at 11:31 PM.

  3. #23
    Member Hitman's Avatar
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    Default Re: DSLR newbie guide + Product/Price/Outlet List

    To the Moderator,

    This is a great effort, shouldn't this be made a 'sticky'?

  4. #24
    Senior Member zoossh's Avatar
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    Default Re: DSLR newbie guide + Product/Price/Outlet List

    Focusing: sharpness and motion

    1. Camera-Subject stillness: Sharpness and Clarity
    1.1 What is sharpness and clarity?
    1.2 What is required in a sharp picture?
    1.3 What is required in a clear picture?
    1.4 Testing of sharpness.

    2. Focusing concept
    2.1 Focusing and the importance of learning it early
    2.2 Focus, focusing, focal point and subject of focus
    2.3 The focusing mechanism in DSLR lens
    2.4 Components of focusing
    2.5 Vision in focusing
    2.6 Focusing at the right place

    3. The viewfinder
    3.1 The viewfinder and field of view
    3.2 The default at the centre
    3.3 Focusing points and markings
    3.4 Ghost image focusing
    3.5 Focusing screen
    3.6 Viewfinder in rangefinder
    3.7 Angle finders


    4. Focusing techniques
    4.1 Autofocusing (AF) and motor in body/lens
    4.2 AF-assisting illuminator
    4.3 Shutter half-lock and release
    4.4 Focus lock button
    4.5 Focusing area (AF sensor/AF area)

    4.6 Directing to the desired focal point
    4.7 Manual centre weighted focusing area
    4.8 Manual navigation to multiple focusing area

    4.9 Automatic navigation to the focusing area
    4.10 Manual focusing

    5. Depth of field
    5.1 Depth of field (DOF)
    5.2 Hyperfocal length
    5.3 Photographic use of depth of field
    5.4 Factors that affect depth of field
    5.5 To achieve a narrow depth of field
    5.6 Problems & issues of a narrow depth of field
    5.7 Blades of aperture & bokeh
    5.8 Stop-down DOF preview button
    5.9 Stop-down metering

    .
    Last edited by zoossh; 3rd January 2009 at 10:41 AM.

  5. #25
    Senior Member zoossh's Avatar
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    1. Camera-Subject stillness: Sharpness and Clarity


    1.1 What is sharpness and clarity?

    This isn't an English lesson and I'm not very good with language either, but is there any need to talk about what sharpness and clarity means? They seem to be simple vocabulary, isn't it?

    The reason why we talk about it is because they have extra meaning in photography, where sharpness and clarity are not god given, and neither is the camera programmed like a laser printer that automatically gives you crisp print. you dun have to worry why and how to do that. In photography, a newbie wonder why and how to do that, and is puzzled as to why their pictures are not sharp and are not clear? Question often asked is what's wrong with my camera, should i change my camera body and my camera lens?

    Before composition, noise, over and underexposed pictures, blurred pictures annoyed a newbie the first and the most. As such, we shall talk about it first - in my own self-derived understanding.

    Sharpness basically lies on the concept that light emitted and reflected from a single point, falls onto the same single point on the sensor. Clarity relates to how accurate the nature of this point of light, after passing through multiple medium is recorded accurately on the sensor, in terms of light intensity as well as color hue and saturation.

    Sharpness perception depends on the source and the output. A sharp image source will have the light falling onto the sensor within a small blur circle or what is more technically called circle of confusion. It is next determined depending on how much you blow up the picture and till the point at which pixelation starts to appear.



    1.2 What is required in a sharp picture?

    Sharpness basically lies on the concept that light emitted and reflected from a single point, falls onto the same single point on the sensor. Light from a single point may emit in all directions unless blocked. The lens help by converging all the light running in different directions from that single point through an optic pathway that eventually all converge all onto the same point on the sensor. Focusing is about precision. Proper focusing is required for sharpness for at least one recognisable location on your photo.

    It means your camera must be fixed and not moving, so must be the subject. The relationship between the camera and the subject must be the same throughout the duration of shutter opening. If the camera moves, the subject must moves at the same rate in the same direction, maintaining the same distance and angle to the camera. Vice versa.

    Of cos, this relationship of proper focusing and a fixed distance is not a microscopic absolute. This is going to be some little mismatch which at a certain size is not significantly perceptible. And whenever this mismatch exceeds a certain magnitude, it will show up as blurring. Blurring of lack of focusing is soft, gentle and circumferential, and the area enlarges as a bright spot is further away from the focal point. Blurring of subject motion can be directional or in a few smooth directions. Blurring of handshakes is multidirectional and erratic in short jerky moves.

    The lack of clarity also affects sharpness, in a few aspects and shall be discussed under the need of clarity and what happens with the lack of it.



    1.3 What is required in a clear picture?

    Clarity is a different concept from sharpness. Sharpness is about spatial accuracy. Clarity is about the accuracy of the nature of light.

    Light emits and reflects from various subjects, went through the air medium, through any smoke, haze, glass windows, and eventually through your filter, your lens and eventually on the sensor. Each of this medium cuts down light and introduces interferences to the intensity of the tone, hue and saturation of the color.

    Clarity affects sharpness directly, but not the same way out of focusing does. It does not bloom significantly into a bokeh (Japanese word for out of focusing blurring) and simply dissipates locally. On the other hand, if there is significant cutting down of light intensity, a more prolonged shutter duration can potentially open up to handshake blurring or subject motion blur.

    Atmospheric factors is sometimes beyond us - except that you can choose to not shoot in haze, or you can find suitable subjects that can still be seen in haze, even partially. Likewise, most would not shoot thru a window pane if they can open it.

    The ability to control clarity included avoidance of interfering medium that is either in front of the lens or the lens itself. By avoiding filters and the stacking of it, by using clean filters or keeping it clean and by using good quality filters are all ways to deal with it. Having a lens with good quality glass is also important for clarity.



    1.4 Testing of sharpness

    From ortega,

    to test your equipment

    1. mount camera on a steady tripod (to eliminate chance of camera shake)
    2. use fast shutter speed (also to eliminate chance of camera shake)
    3. shoot stationary object (to eliminate subject movement)
    4. shoot at a place without the wind factor (also to eliminate subject movement)
    5. have enough light to shoot with a fast shutter speed and stop down your lens at least 2 stops
    6. have enough DOF to cover your subject
    7. focus

    .
    Last edited by zoossh; 19th May 2008 at 06:58 PM.

  6. #26
    Senior Member zoossh's Avatar
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    Default Re: DSLR newbie guide + Product/Price/Outlet List

    2. Focusing concept


    2.1 Focusing and the importance of learning it early

    Considering if lack of clarity is not a perceptible issue, handholding steadiness and appropriate focusing become the main determinant of sharpness. While many factors may affect sharpness, none can produce as much disturbance as erratic handshake and inappropriate off-focus.

    A newbie may not immediately face an exposure difficulty at easier tonal contrast and may only complain of issues at difficult lighting situations that other amateurs may also find difficulty to cope with. Focusing is however a more immediate issue, in many situations, from a standard to tele focal length, low light or low contrast lighting, or a frame with differential subject distances or wide subject to background distance, and sometimes simply focusing on an object that is too near to them.

    The ability to cope with proper focusing techniques and methods to avoid handholding handshake wherever possible is the first step for a newbie to produce decent photos that can be shown to undemanding friends and relatives. When that is settled, then we can talk about having proper exposure, colors, and composition that shows aesthetic and impact, with a final touch with clarity, texture and details. Having expensive lens give you that final touch when one have handled the rest, but a lot more depends on the user as well as features from some relatively affordable but not necessarily very expensive, faster AF (not quantified usually) and large aperture (max. aperture at least f/2.8) lens.

    Dissection of components to focusing, shall later tell you that ease of handling (equipment) and handling skills (user), are both important determinants.



    2.2 Focus, focusing, focal point and subject of focus

    Other than pattern and abstract, most photographic themes have a subject of interest, something that we correlate as the most important part of the picture with the surrounding relating to it, be it the nearest flower in a sea of flower or a person in a crowd who look at you. This subject of interest is often interchanged with the term focus, focal point and subject of focus because the subject of interest is often in focus.

    Focusing is the process of getting the desired focal point in focus. Although we talk about the focal point as a point, virtually everything at the same distance from the sensor within the frame would be in focus.

    In focus means having the subject pin-sharp. Soft focus refer to having perceptible circumferential fuzziness of the subject due to gradual increase of penumbra from malalignment of light. Out of focus refer to evident blotching out of the focal point, and is different from erratic multi-directional blurring from handshake or subject motion. Bokeh refers to the exaggerated out of focus blurring with a large aperture size and shallow depth of field.


    The words at the same distance from the camera are sharp and in focus, with gradual out of focus blurring in front of and behind this line.



    2.3 The focusing mechanism in DSLR lens

    In photography, focusing refers to the shifting of the lens mechanism such that the optical centre of the lens (not necessarily the physical centre of the lens, and may even be outside of it), will enable the images from a certain distance to be projected sharply on the sensor. One may wish to read more about focus and cardinal points.

    This means that depending on where you project the subject of interest you wanted to be sharply in focus, for example, a person's face 20m from you, you point the camera at the person's face in the centre of the frame, with the focusing area set to automatic and centred, the lens elements will move such that whatever that is 20m from you, including the face would be sharp on your sensor and resultant image.

    The calculation of how the lens will shift depends on an in camera algorithm, that depends on your sensor size, focal length setting and the estimated distance from the focus point. The camera will try to find the focus by differentiating the contrasting tones of the area you tell the camera, and by some mathematics and trial and error, the camera will adjust the lens elements position until they make that particular area sharp in focus. As such, one may find difficulty do auto-focusing if they are shooting something where the tones are not contrasting, like a uniform area of black/white/single color, or in general, when it is very dark at night. In that case, you can switch back to the old way, do it manually, view with your eye to judge that the area is sharp, then adjust the focusing ring till you get it right.



    2.4 Components of focusing

    I gradually find that the word auto or automatic can be a misnomer because very often they are semi-automatic with certain things that is decided by user and implemented by the camera. To better describe the various components, I split the focusing process into following components.

    1. Vision (Deciding on the desired focal point)
    2. Adjustment (Directing and achieving focus to the desired focal point)
    3. Locking and following (Maintaining the focal point)
    4. DOF and compositional consideration

    The first three components are practical skills required to cope with focusing, while the last is an aesthetic consideration.



    2.5 Vision in focusing

    It is to me a surprise that hardly anyone teaches you the 1st step to focusing is vision. I’m not talking about creative vision but literally physical vision. A bright and large viewfinder with an appropriate vision is important for one to tell that something is sharp or not sharp.

    There is a few ways to judge many things – eyeballing or quantification. One may see the white balance on a post-shoot LCD review or based on the Kelvin unit. One may judge the frame intensity via naked eye or through the viewfinder, or based on the metering bar. One may see the exposure through the post-shoot LCD review or based on the exposure value. One may judge the exposure distribution through the post-shoot LCD review or via naked eye/viewfinder with the same breath or not the same endpoints, or based on the histogram pattern. In fact the variation in doing things is so wide that really anything is fine as long as you are at ease with it and gets your desired results. There is however a thing that is common – good vision helps you think better and faster.



    2.6 Focusing at the right place

    Does it comes to your mind that you have to focus at the right place? I think many of us did not really think of that becos it is all natural to just point at the main subject of interest, and naturally that is where you want it to be the sharpest. But there is one pitfall when shooting the face, you may have the tendency just to aim at any part of the face, or most probably the nose. In some cases, if you have sufficient depth of field, it is not so apparent. But if you dun.....

    Here's a picture that shows focusing on the nose instead of the eyes. it is shot with a very wide aperture with very little field of depth, so the mouth and the eyes fades off from sharpness. Although my intention really is to shoot the nose, as that is my emphasis in this picture (the red nose in winter) but that might not be what you want, so take it as a precaution....



    It is of uptmost importance in a few subject themes. Human and animals subjects have their eyes as the first point of contact between a picture and the viewer. Once the eyes are not in focus, the picture is pretty much a goner.

    .
    Last edited by zoossh; 19th May 2008 at 06:59 PM.

  7. #27
    Senior Member zoossh's Avatar
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    3. The viewfinder


    3.1 The viewfinder and field of view

    The viewfinder covers about 90-99% of the field of view. In the case of SLRs, it is the same as the exact pathway to the sensor and thus represents the same field of view with some cropping but no distortion (parallax error).

    What do we see in the viewfinder?

    1. The contents of your shot.
    2. Navigation markings on the frame
    3. Settings

    There are a few things that can be or cannot be judged from the contents of the viewfinder.

    First of all, this optical viewfinder reflects an optical image via the mirror reflex into our eyes, which essentially means that other than the fact that light went through slight alteration of quality and intensity upon mirror reflection and the viewfinder prism, we see this optical image the same way we see with our naked eyes directly on the subject. There is instantaneous record of this optical image, with the “shutter duration” a fixed instant duration and the resultant “exposure” as determined by the refresh rate of our vision.

    What we see eventually as our captured picture is the electronic image seen on the LCD of a digital camera, be it a compact or a DSLR. This differs from the optical image seen from the viewfinder based essentially on the concept of cumulative exposure with a variable shutter duration that is set by the user. The shots we take are mostly daytime shots where the shutter duration is often instantaneous, and that is why we may not notice that there is difference between the optical viewfinder and the electronic image produced. Once the shutter duration prolongs, we will start to see the effect of cumulative exposure.

    On a static image, there is constant frame intensity and exposure adds up on a linear fashion depending on the shutter duration. On a non-static image, there is motion recorded, and the exposure cumulate variably depending on the change of the frame intensity which varies on movement of the frame (panning), movement of the subject and change in the light source (e.g. the sun moving into the clouds or additional flash). We usually do not see motion except for the occasional fast moving trains and the blades of the fan. In photography where shutter duration is variable and can be prolonged to record motion of various subjects, this effect is recorded on film or an electronic sensor, and this is not seen through the viewfinder. As such eventual exposure and motion effects are not seen on the viewfinder – something that you have to determine through the eventual output.

    Upon the few determinants of exposure, only relatively constant frame intensity can be easily judged by our eyes directly on the frame or via the viewfinder. As mentioned earlier, effects of shutter duration (especially when different from our vision) and the appearance of the frame with the eventual exposure, are all not seen on the viewfinder. Not just that, the effect of the ISO and exposure compensation on the exposure, and the noise with high ISO are all not seen on the viewfinder.

    We now come to the 4 factor in the exposure equation – the aperture size. That would affect the depth of field which would be discussed in the chapters behind. It may or may not be seen on the viewfinder depending on the mechanism of the camera.

    .
    Last edited by zoossh; 19th May 2008 at 07:00 PM.

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    Senior Member zoossh's Avatar
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    Default Re: DSLR newbie guide + Product/Price/Outlet List

    3. The viewfinder


    3.4 Focusing screen

    Wikipedia link
    Nikon Focusing screens & Types



    3.6 Split-image focusing screen

    I find the following discussion in "photography on the net" the easiest to understand so far, and hopefully can find better explainations in future. The following is quoted and rephrased from the above link.

    Split-image or split-screen is a kind of focusing aid for manual focusing that is available on the focusing screen.

    There is a 3mm diameter reference circle in the middle, with a line cutting across its centre, either horizontally or at 45 degrees. Each half of the circle is made from a small prism. This split circle in the middle is also called central split-image rangefinder, but this got nothing to do with rangefinder cameras.

    When focusing manually, it is difficult to tell if the focusing is spot on hence this device helps me differentiation between sharpness and unsharpness due to incorrect focusing. The split-circle is supposed to be framed or aligned onto a subject with distinct contours, especially if the contours of the subject is vertical, running across both halves of the split-circle. When the subject is not in focus, the top half of the lines will not lineup with the bottom half. When you adjust the focusing ring so that the subject is in focus, the lines will all line up perfectly and the split image will become a sharp, clear, complete and undivided image in focus.

    The images in this website shows how the vertical contours align or disalign with each other.

    The diagonal split has the advantage that you can also focus with it using horizontal lines.



    3.7 Micro-prism focusing screen

    Also quoted from the same discussion in "photography on the net".

    The same principle is applied here except that when the subject is out of focus, the image breaks down into lots of "speckles". When the subject is in focus, the speckles will not be evident. Some people find this type of screen harder to use than the split-screen focusing screen.

    .
    Last edited by zoossh; 19th May 2008 at 07:00 PM.

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    Senior Member zoossh's Avatar
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    4. Focusing techniques


    4.1 Autofocusing (AF) and motor in body/lens

    Autofocusing is one of the breakthrough in digital photography. Autofocusing can be referred to as active or passive where active autofocusing refers to an active measurement of distance to achieve sharp image, whereas passive autofocusing refers to assessment of the image itself to achieve sharp image.

    Current DSLR make use of measurement of contrast within a sensor field through the lens, and look for the difference of intensity between pixels. Lack of sharp focus naturally means that intensity of a pixel are spread out over an area, and averaging out whereas a sharp focus naturally means that a dark and a bright pixel lies next to each other without spilling over to each other. The optical system will thus adjust to-and-fro, to-and-fro, till the maximum intensity difference is measured and adjusted to.

    The data collected from AF sensors will then be used to move the motor either in the body or the lens to a suitable position, where a sharp focus will be achieved.



    4.2 AF-assisting illuminator

    This is an extra light that is located in the front of the camera body. It will automatically blink an orange light when there is autofocusing at dark backgrounds, to improve on the visualisation of details in the dark and help the AF sensor fine tune to the correct focus plane.



    4.6 Directing to the desired focal point

    After you have decided on where you want the focal point, you have to tell the camera where it is.

    The default point where the camera will focus at would be at the centre of the viewfinder, which if there is no further instructions to the camera, and without further changes of the framing, the focal point would be thus at the centre of the viewfinder. Such a default of cos will work only for subjects that is right smack in the centre.

    There is two ways of achieving the focus at a position of different from the centre.

    1. Free movement of frame with autofocus
    - point the frame centred at the subject
    - half press the shutter release button without releasing the pressure
    - ensure that AF manages to secure the autofocus via a beeping notice and/or seeing thru the viewfinder yourself
    - keep the autofocus at that position either by
    a) continuing holding the shutter release button at half-press mode. however, if you accidentally lose the pressure, you may have to refocus again.
    b) using focus lock custom function, which in Nikon D50 is on this button called AE-L/AF-L button, with a menu preset for it to be a AF-L function button. Troublesome and confusing, i would say, and esp when the button is not ergonomic to use.
    c) switching off the AF function on the lens or camera body will keep the focus at the same distance. for Nikon D50, the camera body A/M focus switch is on the left front next to the lens mount. with some practice, you should be able to switch it off fast. but you will need to switch it on again.
    - reframe while maintaining the focus.
    - complete the shutter release by full pressure.

    a) and b) requires holding of a button to maintain focus, and is not suitable when making adjustment on tripods.

    * if focus is done by manual focusing, it will remain at the same focus unless you move the focusing ring. in such a case, it is pretty similar and much more simpler.
    - point the frame centred at the subject (no need to half press shutter release button)
    - manual focus with focusing ring (ensure focus via a flashing notice on the viewfinder and/or seeing the image thru the viewfinder yourself)
    - reframe (no need to hold anything to maintain focus)
    - press the shutter release (no half press before, just snap now)


    2. Using navigation button or dial.

    - tried using a canon 5D from a colleague and was confused. please check your manual or your fellow canon users.
    - for Nikon D50, there is a 4 knob navigator, which will allow you to control movement of the focus area (which is called AF Sensors). In Nikon D50, you will see 4 areas (other than the centre, all together 5) for you to move the AF sensing off the centre.
    - you may focus on these 4 areas without further reframing if you want.
    - however, small adjustments will still be required, nevertheless a fast navigation to an off centre AF sensor can make adjustment faster if you are familiar with the button.

    .
    Last edited by zoossh; 19th May 2008 at 07:00 PM.

  10. #30
    Senior Member zoossh's Avatar
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    4. Focusing techniques


    4.9 Automatic navigation to the focusing area

    The focusing area is known as AF area in Nikon D50. Selection of the AF area can be manual via navigation buttons, or automatic via preset instructions to the camera.

    Thes preset instructions is kept in the menu under AF Area Mode. The default is at the centre where you frame with which you may reframe or navigate, and this is this manual, called the single area "AF Area Mode".

    Automatic focusing area modes may be set to hunt for a moving subject in a static frame (dynamic area "AF Area Mode") or may set itself on the closest subject nearest to you (closest subject "AF Area Mode"). I did an experiment for the closest subject mode and find this not to full-proof. Also it may not recognise a close subject that is in between the limited 5 AF sensors in Nikon D50. As for the dynamic area, i find it hard to experiment and that probably will take a lot of shooting to have a feel, but Ken Rockwell says it works.

    Dynamic mode is self explainatory for birds and sports. I supposed the closest subject is meant for straightforward portrait where there is usually nothing closer to you other than the person. However, that is only for straightforward portrait. For the eccentric, manual use of the single area "AF Area Mode" may be better, such as for the composition below where there is indeed something in front of the subject which is to be out of focus.



    .
    Last edited by zoossh; 19th May 2008 at 07:01 PM.

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    5. Depth of field


    5.1 Depth of field (DOF)

    Quoted from wikipedia (2007 Jan 22), "In optics, particularly film and photography, the depth of field (DOF) is the distance in front of and beyond the subject that appears to be in focus. There is only one distance at which a subject is precisely in focus, but focus falls off gradually on either side of that distance, and there is a region in which the blurring is imperceptible under normal viewing conditions."

    In general, when the depth of field is described as wide, it means that the distance in front and beyond the subject is very long, which could be for example the mountains 5km behind the subject (a person's face) and the grassland 100m in front of the subject, and most of the contents in the frame appears to be relatively sharp. When the depth of field is described as narrow, it means that the distance in front and beyond the subject is very short, which could be for example a glass that is sharp 5cm away from the subject (an ice cube) and the surrounding crushed ice that is sharp within 2cm from the ice cube, and only a small portion of the contents of the frame that is sharp whereas the rest gradually becomes more blur.

    Interactive tutorial on DOF



    5.3 Photographic use of depth of field

    A narrow DOF is used for selective focus and can help to bring attention to the sharp portion which should be the point of interest, e.g. a face in a portrait, while blurring the background or the less important areas.

    By Eikin

    above: sigma 180mm 3.5 at aperture of 5.6, shot by eikin in Japan, Tamagawa riverside. This illustrate a very narrow depth of field, with the flowers in front (foreground) and behind (background) all fade into bokeh.




    A wide DOF is used to ensure that details in the frame, e.g. a landscape, is sharp throughout and would not be lost in blurring.

    By Eikin

    above: sigma 12-24mm 4.5-5.6 at aperture of 22, shot by eikin, in the same thread. Note that you can still see the windows of the houses that is like probably more than a km away, as much as you can see the little leaves somewhere near the focus in the middle. This is what we call "front-to-back" sharpness in a wide depth of field. of cos, there is still some differences in sharpness over the distance, but they are really quite close in terms of sharpness if we didn't magnify them enough to tell the differences.



    5.4 Factors that affect depth of field

    1. distance between subject in focus and its foreground/background
    2. aperture size
    3. focal length



    5.5 To achieve a narrow depth of field

    The common question being asked is often to achieve a narrow DOF, that is in a newbie term, often described as subject being sharp while the background is blurred. The understanding of the above 3 factors in narrowing the DOF will eventually be achieved with some practices.

    In short, what you need to do is
    1. place yourself near the subject, or place the subject near you, while having the background as far away as possible.
    2. widened the aperture size, and make the f-stop number small, e.g. f/2.8 (small number, large aperture size) versus f/16 (large number, small aperture size)
    3. choose a long focal length

    In practice,
    1. The distance and placing is the most important part in achieving the desired DOF. If the background is very near your subject, e.g. a wall just 1m behind a person, there is hardly any chance other factors can help to narrow the DOF, it will almost always be sharp. If it is a mobile situation whereby the subject can be moved, you will have to try to move the subject far away from its background to blur the background. And whether the subject can move or not, you should try to go closer to the subject, such that you are significant nearer to the subject than to the background.

    2. The wider the aperture opens, the narrower the DOF. For common situations, an aperture size of f/3.5 to f/5.6 may start to give some degree of blurring of background and an aperture size of f/1.4 to f/2.8 will often give very satisfactory results. Of cos, this depend on the other 2 factors, and to achieve this, you may need a lens that can give you that maximum aperture size. You can't get the effect of a f/2.8 when your lens have a maximum aperture size of f/4. This is a useful variable that is used to control the DOF, if the distances (point 1) is appropriate, and especially when neither you nor the subject can move to further enhance the effect.

    3. The focal length, if long e.g. telephoto will give a blurred background. However, as the focal length affects the composition drastically, it is often not a practical concern to me. Seldom or maybe never one would sacrifice and change the entire composition just to achieve a narrower DOF. One just have to remember that if you have a wide angle lens shooting a picture at wide angle e.g. 12mm, a narrow DOF is going to be hard to achieve.



    5.6 Problems & issues of a narrow depth of field

    Of cos, the first thing is to have a lens that can give the necessary large aperture size. Most entry level lens or cheaper lens would have a maximum aperture size starting from f/3.5 to f/4. If you have a situation of a very near subject and a far away background, that should suffice even if you have a very short focal length at 10mm as long as the distances are appropriate. To get a better effect or to rely less on the distances required, a larger maximum aperture size may be needed, and that means an investment into a prime lens that is f/1.4 to f/2 for example, they are relatively affordable and are light, or into a zoom lens at f/2.8 maximum aperture size, which requires a premium to pay for its costs and which are never light enough.

    With some practices, one should be able to estimate, for his desired DOF, the kind of distances he should place himself and the subject, in relationship to the background which in most cases can't be moved.

    The first issue is the minimal focusing distance of the lens. One cannot placed the subject closer to himself than what the minimal focusing distance of the lens can give. If my nikkor 50mm f/1.8 AF D have 50cm minimal focusing distance, i have to be 50cm or more away from my subject, e.g. a plate of noodles. If I try to force the subject to be too near me to get a narrow DOF, then i will fail to lock an autofocus. If one is using manual, and did not pay attention to getting the focus right, the whole picture would be blurred.

    The 2nd issue is not to overplay the narrow DOF. Preferably, you dun want to have only the nose on a face to be sharp but rather the whole face to be sharp, at most, with blurring starting from the fringe and the ears. If you can afford an aperture size of f/1.4, you dun always have to use that, sometimes an f/2.8 is required to have a narrow but sufficient DOF for the whole subject to be sharp.

    The 3rd issue in a narrow DOF is not to get your focus at the wrong place. For example, get the eyes sharp in either a human portrait or an animal, not the other parts of the face sharp while having the eyes less in focus. This isn't that bad when shooting a human portrait but can be very important if you are shooting an animal that have a long face, e.g. a horse.

    .
    Last edited by zoossh; 19th May 2008 at 07:01 PM.

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    5. Depth of field


    5.7 Blades of aperture & bokeh

    Bokeh, a Japanese word boke (ぼけ), means blur, and in photographic term refers to the area on a picture that is selectively out of focus, as a result of it being outside of the depth of field (area of the picture which is acceptably sharp). More can be read here from wikipedia.

    While there is no uniform standardised definition of this term, it is often used as a desired technique and effect with elements of sharpness and blurring, due to the relationship of subjects in the depth of field and those out of the depth of field, in contrast to effects achieved by panning (e.g. velocity sport) or anticipated movements in static background with prolonged shutter duration (band concert, dance, star trail), where elements of sharpness and blurring are achieved not by differential focus, but by differential movement. And again, it is to be differentiated from more uniform blurring caused by soft focus, chromatic aberation or the wrong focus.

    The degree of bokeh, is basically determined by the same rules for a narrow depth of field, where more of the picture falls outside of that narrow DOF, and thus give a stronger element of blurring. Thus, with a longer focal length, a wide aperture, and a far distance of background/foreground to the subject, the bokeh will show a stronger degree of blurring with a larger diffusing out of each dot, a feature of out of focus element.

    Other than the degree, there is also characteristics of the bokeh, especially evident in those with a strong degree of bokeh, where the diffusing out of the dots may appear as rounded or hexagonal or of other shapes, and that depends on how the blades of the aperture is shaped. Therefore each lens, with its unique blade arrangement, will give a different kind of bokeh characteristics.

    Hence, the degree of bokeh is determined by the settings associated with the depth of field, ie. the subject/background/foreground distance (photographer position and ability to move subject and background), the focal length (within the limits of the lens, set by the photographer) and the aperture size (within the limits of the lens, set by the photographer), whereas the characteristic of the bokeh depends totally by the lens design and is not alterable or controlled by the photographer.

    The use of bokeh, in aesthetics, serve the purpose of
    1. introducing the feel of near and far distance, i.e. depth, the 3rd dimension, other than using scale and converging lines.
    2. isolating and emphasizing the subject of interest by blurring off the less important areas
    3. obscure recognisable unwanted elements, e.g. grills and grids of a cage for animals in the zoo

    The bulk of use in bokeh can often be found in
    1. single subject photography, e.g. a simple portrait of a human or of an animal, or in certain still life and abstract, or in
    2. more complicated compositions, e.g. wedding and travel photography

    I have very much been inspired by one of our forumer who demonstrated wonderful use of selective focusing and understanding of zonal composition, and would like to link two of his thread here - wansheng aka w.s, in Germany and in Bali.

    .
    Last edited by zoossh; 19th May 2008 at 07:01 PM.

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    5. Depth of field


    5.8 Stop-down DOF preview button

    This button is available in some of the higher end model. Basically and literally to preview the depth of field.

    What happen is that when you look through your viewfinder from perhaps a nikkor 18-55mm f/3.5-5.6 lens and you frame at 18mm, you will see the light entering through an aperture of f/3.5 bouncing onto the mirror into your viewfinder. Even though now you change the aperture setting on the body from f/3.5 to f/8 to f/16, the viewfinder still shows the light entering via an aperture of f/3.5. The light enters your eyes instantly and continuously. Only when you pressed the shutter release, would the lens diaphragm respond to stop down to f/16 momentarily, with the mirror flipping up, and the light enters and falls on the sensor for that shutter duration as controlled by your mode of control, ISO, metering, exposure compensation and aperture size. And when the shutter duration completes, the shutter closed while the mirror and the diaphragm returns to its original position.

    Therefore with regards to DOF, you are seeing the frame at f/3.5 through the viewfinder while the sensor capture the frame at f/16, hence there is a difference in depth of field between what you see through the viewfinder and what the resultant image shows. And when the sensor is capturing the frame at f/16, that is when the mirror flips up and thus there is no way you can see the depth of field that appears in the resultant image when the shutter is opened for action. This is where the DOF preview button come into place.

    With the preview button available, pressed and hold, the aperture stop down to f/16 as preset, with the mirror in its resting state and the shutter in its closed non-shooting state. This gives you the idea of the DOF that is to be expected, before the actual shutter release and mirror flip-up, and that is exactly what is meant by preview. Once you got your preview, and you are happy with your aperture setting, you can release the DOF preview button and the rest is the same as per normal.

    The tricky issue and limiting factor is that when you preview through the viewfinder, an reduced aperture size may cuts down the amount of light entering the lens and make the viewfinder too dark to discern any composition and details, thereby limiting its function to preview DOF.

    However, if you can discern the details in a dark viewfinder with much eye strain, you need not worry again about the resultant image being as dark as what you see in the viewfinder. While the DOF is similar in a viewfinder under DOF preview compared to the eventual image produced, the exposure is different in a viewfinder under DOF preview compared to the eventual image produced. Take note that your eyes see the reduced light constantly, whereas the sensor captures the reduced light cumulatively over a time (its respective shutter duration).



    5.9 Stop-down metering

    This is probably more of a concern to veterans becoming DSLR newbies that used manual lenses on newer electronic bodies.
    And this is mainly discussed in relation to DOF preview function.

    As described in photonotes.org, this literally refers to the camera body taking a metering of light from the framing via an aperture that is stopped down to a smaller aperture size at a larger f-stop number.

    To paraphrase the description in photonotes.org,
    modern SLRs usually take metering with the aperture size at its widest resting position such that the viewfinder remains bright enough for you to compose your framing, but will subsequently adjust the metering level accordingly to the f-stop number you set. This adjustment in the camera body requires the ability of the body to be able to control and read the aperture size, such that metering from the resting position can be adjusted to the appropriate metering for the actual f-stop number at which the photograph is taken at.

    If the lens is meant for another system to your camera, the setting of aperture size on the camera body may not be able to control the aperture change in the lens. An example would be Canon EOS camera bodies which relies on lens with electronically-controlled aperture diaphragms. They does not have a mechanical lever to stop down the lens aperture when the photo is taken, but rather use an electronically controlled mechanism. Lens which rely on a mechanical lever or an incompatible electronic system will hence not work with these bodies in terms of aperture control from the body setting. Further description of Canon EOS bodies with manual lenses, covering this issue, can be found here under photonotes.org.

    In such a case, aperture setting is controlled entirely on the lens and not known to the camera body, and as such no adjustment of metering would be done. As such, a stop down metering would be required.

    Hence, for compatible lens and body, it will be as such

    at widest resting postion, view through viewfinder (brightest) + metering through the lens (at maximum aperture size)
    aperture size is controlled & preset on the camera body either manually or automatically, and metering is adjusted on the body
    when shutter release is pressed, lens stop down rapidly to the specified setting, takes the photo and after the shutter duration completes, returns to the resting aperture size again.

    With a stop-down metering, it will be as such

    at widest resting postion, view through viewfinder (brightest)
    aperture size setting is preset on the lens manually, no adjustment to metering is done on the body
    when shutter release is pressed, lens stop down rapidly to the specified setting, metering is done, it takes the photo and after the shutter duration completes, returns to the resting aperture size again

    .
    Last edited by zoossh; 19th May 2008 at 07:02 PM.

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    2.2 Lens mount

    Different brands would have different designs of the connection between the mount on the body and the fittings on the lens. There are various technical reasons, but one of them is to lock the consumers to their initial investments of the lens so that they would stay with the same bodies form the same company.

    Each brand may have different generations of its mounts, but usually keep to one mount at a time. There are 3rd parties companies that may provide lenses with fittings that is compatible for the larger manufacturer too. So it could be a sigma brand with sigma, canon or nikon mount.

    Some brands shared their mounts by commercial partnership, namely the F mount of Nikon which can be used by Fujifilm DSLRs, and the 4/3 system shared by a few brands now.

    Some of the bayonet mounts include
    Nikon F
    Canon EF & EF-S
    Pentax K
    Minolta-Konica-Sony alpha
    Four Thirds
    Sigma SA
    Leica SLR R and rangefinder M
    Hasselblad C

    Common non-bayonet mounts currently include
    Universal M42 screw mount

    Other mounts include
    C/Y Contax/Yashica 35mm FSLR bayonet mount: Contax, Yashica/Kyocera, Zeiss lenses
    Contax G series 35mm RF AF bayonet mount
    Contax N series 35mm SLR AF bayonet N-mount
    Contax 645 mount: Zeiss, Hasselblad C, CF, CFE, CFI, F and FE lenses


    More notes on the common mounts

    Nikon F:
    Extracted from wikipedia (2006 Dec 31), F-mount photographic lenses are currently made by Nikon, Zeiss, Voigtländer, Schneider, Sigma, Tokina and Tamron.

    Canon EF & EF-S:
    Extracted from wikipedia (2006 Dec 31), the EF (Electronic Focus) lens mount is the heart of the Canon EOS line of cameras made by Canon Inc. Third-party lenses compatible with EOS electronics are manufactured by Sigma, Tamron, and Tokina. The EF-S (Electronic Focus - short back focus) lens mount is a derivative of the EF lens mount created for a subset of Canon digital single-lens reflex cameras with APS-C sized image sensors (reduced sensor size). The cameras that use the EF-S mount are: the Canon EOS 300D, 350D, 400D, 20D, 20Da, and 30D digital SLRs. (look here). Short back focus implying that the rear element of the lens is closer to the sensor than with regular EF lenses. EF-S lenses will not mount on Canon film SLRs or Digital SLRs that do not have an EF-S mount" from OCAU wiki

    Pentax K:
    Extracted from wikipedia (2006 Dec 31), K-mount photographic lenses are currently made by Pentax, Voigtländer, Vivitar, Zenit, Vologda, Sigma, Tokina and Tamron.

    Minolta-Konica-Sony Maxuum/Dynax/Alpha:
    Extracted from wikipedia (2007 Apr 29), the Minolta AF camera system was marketed as Maxxum in North America and Alpha (or α) in Japan and the rest of Asia. The name Dynax was introduced later. When Sony acquired Konica Minolta's camera technologies in 2006, they chose the "α" brand name (already in use by Minolta in Asia) for their new "Sony α" digital SLR system. The Dynax/Maxxum/Alpha lens mount (which was retained from the old cameras) is now officially known as the "α mount system". 3rd parties lens include Sigma and Tamron.

    Four Thirds:
    Extracted from wikipedia (2007 Apr 29), is a a registered trademark of Olympus, created by Olympus and Kodak. It is based on the aspect ratio of the new sensor that is 1.33 or 4/3. Camera bodies with such mounts include Olympus, Panasonic and Leica, whereas the lens with such fittings include Olympus, Sigma and Leica.

    Sigma SA:
    Extracted from wikipedia (2008 Mar 21), SA-mount photographic lenses are currently made by Sigma for their own bodies. It is physically similar to the Pentax K mount but uses a flange focal distance of 44 mm, identical to that of the Canon EF lens mount. The mount uses only electrical communication between body and lens, like the EF mount, and in fact uses the same signalling lines and protocol as the EF mount, despite the physical incompatibility.

    Universal M42:
    Extracted from wikipedia (2006 Dec 31), since there were no proprietary elements to the M42 mount, many other manufacturers used it; this has led to it being called the Universal thread mount or Universal screw mount by many. The M42 mount was popularized in the United States by Pentax; thus, it is also known as the Pentax thread mount, despite the fact that Pentax did not originate it.

    Leica M:
    Quoted from wikipedia (2007 Dec 08), the Leica M mount camera lens mount was introduced in 1954 with the Leica M3, together with a range of lenses. It has been on all the Leica M series up to the current Leica M7 and Leica M8. This lens mount has also been used by Minolta on the Minolta CLE rangefinder camera, by Konica on the Hexar RF, by Voigtländer (Cosina) on the late models of the Bessa range, by Rollei on the Rollei 35RF (practically a Bessa under Rollei's name), and very recently by Zeiss Ikon on the latest Zeiss Ikon rangefinder camera.

    Leica R:
    Quoted from wikipedia (2009 Jan 11), some lenses are compatible with all of the Leica SLR cameras, while R-only lenses have a slightly different mount shape which will not fit on the earlier cameras.

    Hasselblad C-mount:
    Quoted from Rob F. and Simon Galbally in photo.net, the "CF" means that the lens has a (C)ompur (leaf) shutter, and can also be used with a focal plane shutter. According to Hasselblad, the "i" in "CFi" stands for "improved." They explain that the "i" lenses have such improvements as newer coatings, better mainsprings, etc. The "CFE" means that the lens has these improvements, plus an electronic data bus that has the necessary electronic connectors for use by the 200 series cameras.

    With the FE series, the letter "C" is dropped. This lens series without the C designation refers to all lenses built specifically for 200 series camera use thus not requiring an in-lens Compur leaf shutter. The "FE" has all of the former, but they have no Compur (leaf) shutter. The lenses for these 200 series cameras do have in-body focal plane shutters, and has been made faster, except for the 80mm, which is still f/2.8.



    Futher information from wikipedia on other lens mount

    .
    Last edited by zoossh; 11th January 2009 at 11:26 PM.

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    5.2 Close-up filters

    As quoted by Bob Fately in betterphoto forum, diopters or "close up lenses" as they're often called, come in different strengths (typically noted as +1, +2, etc.).

    It works only when it is attached to another lens. Exactly how far from the subject you can get depends on the focal length of the lens you're attaching the close-up lens to. The longer the focal length of the main lens is, the further away from the subject you can be. And the higher the number of the strength, the closer you will be able to focus on (what you lose is the ability to focus at infinity while the close-up lens is attached). This is all a matter of a few inches; it's not as though you can get a close-up of a butterfly from across the room in any event.

    It is a single optical element that closely resemble a filter and therefore usually fits like a filter with a screw thread. The dimension quoted often is the same as a filter coming from the rim diameter that fits the front thread of the main lens.



    5.3 Extension tubes

    Readings:
    Shutterfreaks.com: Extension tubes for macro photos by Rick Bell
    Close-up and Macro Photography for Entomologists by Alan Wood

    It is a cheaper alternative to specialised macro lenses provided they are simple tubes without metering and autofocusing electric couplings. Once such functions are expected, they become sophisticated and can be expensive. The lack of metering and autofocusing couplings is less of an issue if a photographer is used to manual exposure and focusing when shooting macro.

    These are barrels that can be attached between the lens (via a rear lens mount on its front) and the body (via a camera body fittings on its back). They do not contain optical elements, and the sole purpose of putting it in between the body and the lens is to move the lens farther from the film or digital sensor and decreases the minimal focusing distance, thereby increasing magnification of subjects that is nearer to the lens.

    As it does not contain optical elements, it reduces image quality(IQ) less than teleconvertors, with less loss of light intensity (brightness) & sharpness. However, there will be a loss of ability to focus on infinity as the extension tube does prevent the rear of the lens to move all the way back to focus at infinity. The same mechanism of having an empty tube to allow for moving away of lens element can be manufactured and built into existing lens, but is not chosen so because of concern of production costs and to maintain optimised optics throughout a lens capability, as such the extra versatility at the expense of image quality can only be sought by additional separately acquired tools, which form the basis of extension tube.

    And because there is no optical elements, the focal length is not altered. The equation is governed by the following formula, as quoted from Edward Ingold from photonet forum: Extension tubes work by moving the lens further from the sensor than the focusing mechanism alone can handle. The basic optical formula is as follows:

    1/f = 1/f' + 1/f"
    Where f = the nominal focal length, f' = the distance from the film plane to the rear node, and f" = the distance from the front node to the subject.

    f' = f + e
    Where e = the total extension (including the focusing helix and extension tubes).

    Extension tubes gives the most change in magnification when the original focal length of the existing lens is short, and become more and more negliable when the focal length lengthens. Quality varies according to lenses and combinations, and not all lenses are able to accomodate an extension tube.

    Unlike lenses with long focal length, the working distance is not increased in extension tubes and macro lenses. A long focal length, e.g. 500mm lenses for bird watching, enables one to magnify a distant object from a safe distance that does not alert the live subject, whereas a macro lens more than 100mm as compared to one that is just 60mm also increase that working distance for small insects that can be stuttled if too near. Extension tubes and macro lenses however works by going near, with shorter minimal focusing distances, rather than getting larger magnifications at a long physical subject-camera distance via a long focal length. This spell the difference between long telephoto lens and macro lens/extension tubes, as their working distances differs despite of both able to achieve high magnification.



    5.4 Reversing or Inversion rings

    Close-up and Macro Photography for Entomologists: Reversing Rings by Alan Wood

    These rings are like an adaptor that can reverse the orientation of the lens when fitting onto the mount of the camera body. It means the front and rear of the lens are reversed, and the front element face the camera body while the rear element face the subject.

    The camera body mount will attach the "rear lens fitting" imitate of the reversing ring, and the male filter thread (like any filters) of the reversing ring will then attach the female filter thread of the lens at its front end. The free end that is pointing on the unattached side will thus be the lens rear element, instead of the front element which is facing the attached side. The reversing ring is attached to the lens front female filter thread, which thus is not limited by the brand, since all front filters are of the same configuration except for the diameter.

    The suitability and performance of such inversion depends from the respective brands of the camera body and the design of the lens. Long heavy lenses are not suitable for inversion as the lens front female filter thread are not designed to hold the weight like the lens rear fitting does.

    Inversion rings are comparatively to other macro equipments, smaller, lighter and relatively inexpensive, allowing attachment to multiple lens from different brands, but achieve only fixed magnification, while losing the autofocusing ability in most cameras and exposing the rear element and coupling devices, which may require certain protection as listed in the article above.

    .
    Last edited by zoossh; 2nd August 2008 at 07:18 PM.

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    5.5 Converter Lenses

    Readings:
    Digicamhelp
    Overview of Nikon Lens Converters

    These are lenses that are used to expand on the versatility of the built in lenses of a compact camera, typically separately into the following three functions: fisheye converter, wide angle converter and tele converter.

    This is typically in the case of compact camera having a small sensor and hence the lack of a wide angle 35mm equivalent focal length, where the wide angle converters overcome this barrier. Of cos, the other alternatives is to use certain compact camera that offers a wider angle in the existing built in lens or to simply use a digital rangefinder or DSLR with interchangeable lenses. Teleconvertors are also used in the case of DSLR, as existing tele lenses for DSLR are very expensive and focal length and often limited to 200mm or 300mm, so the cheaper teleconvertors give the versatility to add the reach at the expense of optical quality when certain situations requires.

    They may require additional adaptors to allow attachment between the built in lens and the converter, which usually comes with the converter, or may be 3rd party.

    They are afocal elements which means that parallel light entering one side will also leave the other side parallel, and it by itself has no focal length, hence it cannot be used alone. Converters are thus used to modify existing focal length and multiply it by a certain manner. Multiplier that is less than 1 refers to wide angle and fisheye converters, such as 0.63x of the Wide Angle WC-63 converter that will convert the existing focal length of 38mm - 115mm to 24mm - 72mm. Multipliers that is more than 1 refers to tele converters, such as 2.00x of the Tele TC-E2 converter that will convert the existing focal length of 38mm - 115mm to 76mm - 230mm.

    Pro is the ability to use your existing compact camera and still achieve a focal length only possible on a DSLR with interchangeable lens.

    Con includes
    1. Inevitably increased bulkiness, sometimes defeating the purpose of having the compact camera which is after to make it compact.
    2. The large size of it may also block the flash sensor and flash output window, affecting the use of both internal and external flash.
    3. Cameras using an optical viewfinder can also have the viewfinder blocked, however that shouldn't be the case for electronic viewfinder which is through the lens.
    4. With whatever things added in front of the existing lens, they may appear within the field of view of that lens, thereby giving rise of physical vignette and potentially optical vignette. Adding filters in front may worsen this problem. Checking for vignette is best done on computer screen rather than on the viewfinder which is usually a certain percentage smaller than the actual image.
    5. Increased numbers of glass elements with combined or overlapping aberrations, or that due to misalignment, can give rise to more aberrations, such as lens flare, ghost image, barrel distortion and chromatic aberration.
    6. Need to check compatibility of the converters on the compact camera in terms of metering and autofocusing, where information is often with the documentation of the converters.



    5.6 Tilt-shift lens

    Example: J-Chan's HDB scapes



    6.1 Lens review site
    photozone



    6.2 Lens: Sweet spot

    This refer to the best optical quality of a corresponding lens at its own optimal aperture size. Usually as the aperture size gets smaller, the bokeh gets lesser and lesser and the pictures gets sharper. But reducing until a certain aperture size, the small aperture size may results in increasing diffraction of the light, which reduces sharpness instead.

    Read this thread to see relevant discussion. Google online to see where is the sweet spot for your lens. It is typically between f/8 to f/16.



    Optical quality and deficiencies

    Read "lens element and image quality" in cambridge in color's understanding camera lenses, e.g. lack of contrast, chromatic abberation, vignetting, blurring and distortion



    6.4 Vignetting

    wikipedia

    This refers to a reduction in image brightness in the image periphery compared to the image centre.

    Solution to vignetting include
    1. centre filters
    2. software plugin

    Read here for more information on anti-vignetting.

    .
    Last edited by zoossh; 2nd August 2008 at 07:18 PM.

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    Default Re: DSLR newbie guide + Product/Price/Outlet List

    7. Filters


    7.1 Types of filters

    A summary from Galdor.
    A Guide to Common Filters By Nelson Tan

    In general, filters are translucent to almost transparent material attached in front of your lens. They are often categorised by functions, shape and attachment features.

    First by function, generally into
    1. clear protective
    2. antireflection, darkening, contrasting and intensifying
    3. blurring, diffusing or softening
    4. coloring
    5. close-up
    6. special effects.

    For the filters meant for antireflection, darkening, contrasting and intensifying, they fall into the exposure controlling filters which would be discussed Page 12, 4. Control and adjustment of exposure outside the camera.

    The most commonly used filters are as follows,
    1. clear protective filters, such as UV and skylight filters, meant for all situations, especially in dusty environment
    2. exposure controlling filters, especially in outdoor and landscape situations whereby light cutting down is required.
    3. colored filters, used in controlling of tones in a certain color channel in black and white photography by cutting down light of the contrasting color opposite in the color wheel.

    As mentioned above, landscape photography is a field where filters are commonly used because of the tonal discrepancy that can occur to much extent and variation in the sky. Exposure controlling filters, such as CPL, ND and GND filters, are commonly used and pretty essential for fine control. Due to the increase ease of white balance control in-camera and post-capture (post processing), white balance controlling filters (such as the warm up 81 series and cold blue 85 series) that are more commonly used in film photography is now less used, but nevertheless can be useful if one didn't find it a hassle or find it difficult to fine tune in post processing. Jcryan55 has great recommendation and great results here to show with regards to filters and landscape photography.

    Secondly by shape, generally into
    1. circular (fixed or rotational)
    2. rectangular (moves in 1 direction up-down or left-right)

    Rectangular filters are required in graduated effects, as the horizon is fixed in the middle in circular filters. Turning the circular filter will rotate and tilt the graduation.

    Thirdly by attachment features, generally into
    1. whether the attachment to the lens is via a screw thread (round), a bayonet catch (round) or by tension on a holder (round with teeth or rectangular).
    2. whether the front of the filter's rim has another screw thread that enable stacking.



    7.2 Size of round filters

    The nomenclature of round filters are judged by its diameter of the rear rim (male part) and compatibility with the front screw thread (female part) of the lens. The typical size of a fast f/2.8 lens is 77mm, but it can be anywhere between 52-77mm for most of the lenses out there. It varies.

    For protective filter, such as a UV filter, it is best to get corresponding sized filter for all your lenses, as you want to reduce the number of times you are going to screw on and unscrew the filter.

    For the other filters that are only to be used occasionally, one can either get a single size of 77mm for his filter, e.g. a 77mm CPL filter, and use it on different lenses with different front thread size via different adaptors called stepping rings. A step up ring may or may not introduce physical vignette, while a step down ring will introduce a vignette. Also, the use of step up rings may interfere with the use of other accessories, including rectangular filter holder, lens hood and lens cap.

    The choice of size wil thus depend on your habits of handling of filters and use of other accessories.

    .
    Last edited by zoossh; 19th May 2008 at 06:50 PM.

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    Default Re: DSLR newbie guide + Product/Price/Outlet List

    7.4 Filter as protection

    Typically a UV filter is used. UV filter are supposedly absolutely clear and without any color cast. It is also supposed to be negligible in stopping light.

    As such it is able to prevent direct contact with the front element of your lens, if you leave it on the lens at all time. If it is left on the lens most of the time, and occasionally taken out, it will help to reduce the change of dirtying or scratching the front element of the lens. As to how much it will minimise the chance of scratching the front element - it depends on how careful you are when the lens is left exposed.

    As to how much the filter will reduce the clarity of the lens, this depends on the user's demand/sensitivity for clarity more than anything else. Most users will not see visible differences, especially laymen and newbies, even if a scratched UV filter, whereas some claim a noticeable difference. However, if you are still at the stage of having unexplained handshake, poor focusing and just using a simple kit lens, it is unlikely that the clarity between not using and using a UV filter would be of importance.

    A similar question may be ask of a minor scratch or a blunt blotch on your lens, would it then affect optical quality if similar defects on the UV filter does not cause noticeable differences to an untrained eye? I wouldn't want to try, and there is no cut-off between a minor or major scratch, and the same action of exposure can give rise to possibility of either.

    The metal rim of the UV filter helps to reduce impact on the lens body if there is any drop or serious knock. Cracks or breaking of the UV filter hopefully occurs without the break of glass in the lens nor damage to the electronics.

    Alternative to using UV filter as a protection to dirtying or damage to the lens front element includes
    1. using a sky light filter
    2. using a lens hood
    3. using an attached lens cover that is close when not shooting, e.g. optechusa flip-open lens cover.
    4. not using protection, relying on careful handling alone

    A skylight filter functions the same as a UV filter as a PHYSICAL protector. There is however different filtering characteristics. Skylight filter has a faint pink cast which warms up a picture, but is otherwise relatively clear. A UV filter has no significant filtering effect on modern DSLR who has an inbuilt UV filter in the low pass CCD and with modern sensors relatively unaffected by UV light unlike film. There is hardly any difference unless at very high attitudes with haze where UV is higher.

    Lens hood is another favorite for proponents of filters causing decreased optical clarity. To a certain extent, not using filters at all also cut down on the likelihood of stacking filters which can cause flares of light blotches from reflections between the filters. However, lens hood will first extend the length of the lens and if not reversed when keeping, can lead to an increased demand for volume of storage in bags. You can however reversed it when keeping and put it in place when using, but with a hassle. And secondly, putting on lens hood excludes the addition of other things in front of the lens, such as an optechusa lens cap, a cokin rectangular filter holder, a step up ring for larger circular filters and other protruding things in front. You can however still put on a same sized circular filter or a same sized lens cap while the lens hood is on - but that means increased danger of dirtying the front filter when done blindly by feeling. You can also take off the lens hood and apply whatever you want, and reapply the lens hood, but again with hassle and some likelihood of dirtying the front element of the lens.

    Do a seach on optechusa lens cover to see what is meant above.

    Rely on careful handling alone, at your own risk.



    7.5 Which UV or clear filter to get?

    put it simply, a protective filter should be as clear as possible to avoid decreasing optical sharpness and color cast. in terms of protection itself, all of them works. but in terms of cleaning/durability and optical clarity, there are differences.

    One of the cheapest available is Hoya, from $10 to $60 depending on filter sizes. It is said to have less clarity when compared to other UV or clear filters, but is the cheapest around with acceptable quality. B+W are definitely easier to clean than hoya. NC is in between with plenty of nikon supporters too. Kenko, Marumi and Tokina filters are less commonly used but with satisfied users.

    optical sharpness is, in term of photography, not the most crucial part, especially to newbies becos unsharpness due to many other reasons are more often the case. you do need to think about this when you are pretty satisfied with your compositional, focusing and metering skills, that optical sharpness becomes then a top priority. besides, if you handle the filter frequently enough, eventually the filter can be dirty and optical sharpness may not differ so much between brands.

    for short term usage and tries, hoya will do. for long term usage, the better filters are better becos UV filters tend not to be removed and does not get dirty like the rectangular filters or other secondary rounded filters. and with good easy cleaning and/or resistance to scratch, UV filter can serve a long time.

    Many users used either B+W UV or Nikon NC filters, both with excellent clarity and relatively resistance to minor scratches, and with fairly careful use should be able to last at least a year.

    quoted from ianpaice,
    B + W are for ppl who prefer shooting and less cleaning. It has very good resale value. You could sell it at a minimal loss later on.
    Hoya are for ppl who has time and dun mind cleaning and do not suit ppl who shoot outdoor even in very light drizzle. Hoya may be suitable for those very careful in their handling and dun shoot in the outdoor under harsher conditions. They may be tougher to sell. With all that smudges and scratches, you could hardly sell it at a high price.



    7.6 Multi-resistant coating

    Multi Resistant Coating (MRC) is a commerical terminology that we come across for B+W round screw on filters, that many of us used for our DSLR lenses. Essentially these multi-coatings are supposed to be able to reduce internal reflections while allowing minimal alteration of the light entering the lenses.

    Resistance in this aspect refers to less susceptibility (compared to normal filters) to mechanical scratches as well as easier cleaning as compared to say hoya - one of the major influences for those who often do their photography in the streets or field.

    B+W claims of resistance to influence of dust and moisture is not immediately apparent to me, in particularly to moisture. It still fogs when there is a change in temperature and humidity. It could have been worse though with other filters, that i'm not sure. And nope, i did not try splashing my filter with clear water like what B+W has done, but in occasional field conditions, rainwater or dirty splash does smear the filter, and unfortunately they are easily cleaned off. Comparatively, scratch resistance is far more important than moisture resistance, as that is more commonly encountered.

    Those with multi-coating without additional resistance as above is known as MC.



    7.7 Filter for antireflection, darkening, contrasting and intensifying

    Description of these types of filters are covered in details in Page 14. 4.4 Exposure controlling filters.

    .
    Last edited by zoossh; 19th May 2008 at 06:50 PM.

  19. #39
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    Default Re: DSLR newbie guide + Product/Price/Outlet List

    8.1 Lens Cap

    Apparently to protect lens filter and/or lens front element when not in use. Generally attached by clipping/snapping on (also called push on) with internal spring mechanism and in some rarity screw on, and generally divided by the type of detachment, which can be front (centre) pinch or side pinch.

    Side pinch caps are easier to clip on and off. It is especially easier to clip on and ensure proper placement, as you will be able to feel the edges of the cap with the lens should there be disalignment. For front pinch caps, you may indirectly infer proper placement if the attached cap does not feel shaky and loose but it is possible that misalignment causes only one side of the cap clipping on while the other side is only partially clipped on, but most of the time still secure enough.

    However, side pinch caps suffer majorly from easy accidental loosening whenever it is accidentally pressed on the sides, especially when knocked or abraded against certain objects on the go or in the bag. Another major design flaw is side pinch caps cannot be used with a lens hood which leaves no space to the side of the caps for removal or attachment. A front pinch cap therefore has to be used.

    There are occasional alternative products of interest. Optech have neoprene caps that is called hood hats, which is applied over the hood or thus behaves like a lens cap although over a lens hood. Some telescopic lens have specific lens hood that is like the optech hood hat, which is slipped over like a sleeve, and with one end fastened by cords that you can pull, e.g. this one.

    Optech also has a plastic fast cap that is hinged on one side by a metal pin, allowing fast opening (spring loaded) and closing without losing your cap, but the thickness of the cap only allow a single filter when closed (other filters are to be put between the lens and the cap), and the screwthread diameter is only up to 67mm, thereby rendering non-compatibility to most of the professional and wide angle lens with 77mm front element screwthread diameter. It also cannot be used with a cokin rectangular filter just like a lens hood does. Moreover it is expensive and only available imported (in the case of Singapore). I have so far used it for my nikkor 50mm f/1.8 which has often no use of other filters apart from a UV filter.

    Usually one have to have a habit of keeping the lens cap, typically in one particular pocket. Lens cap is easily loose and will benefit from the habit of proper keeping and backup lens cap especially if lens hood and hood hat are not used. With the exception of the hinged cap from optech, all other lens cap that must be detached when camera in use will suffer from potential misplacement. Some side products such as sima capkeeper allows a elastic cord stick on the the lens cap and the other end banded around the lens. It is of cos cumbersome and unprofessional looking with the cap dangling in mid air when shooting unless you hold it with your left hand that holds the lens. The sticking onto the lens cap may not hold for long, and after a year or two can drop off, leaving an ugly white protrusion on your lens cap. Fortunately both are not expensive.

    Lens cap require not the screwthread (except for the rare screw on caps) but the protruding wall of the screwthread to clip on. If filters are used, most filters have both a front and rear screwthread that holds on to the lens from the rear and the cap on the front. However, if a slim filter is being used, most of the time, the front screwthread is not included in the design and cannot hold a lens cap. Fisheye lens with a protruding front element also cannot be used with a lens cap, as such the same as for rectangular filter holders too.



    8.2 Lens Hood
    Discussion in cs
    Lens Hoods - Do I Really Need To Use One? (from Digital Picture.com)
    Printable lens hood

    Use of lens hood is to
    1. Reduce stray light and veil-like glare, thus improve contrast and colors
    2. Reduce stray light and sunspot-like flare, thus reduce change of blotch of unwanted colors
    3. Reduce chances of itchy fingers touching front element
    4. Reduce chances of your own finger touching front element
    5. Reduce impact on front element upon fall
    6. Prevent contract on front element upon impact with surrounding structures.
    7. Reduce water droplet if used in rain or with waterfall.
    8. Look more professional for professionals with an image to keep

    Problems with lens hood
    1. Need to have specific lens hood for each lens.
    2. Specificity means they are expensive.
    3. Takes up space if kept on.
    4. Troublesome to reverse mount to reduce space when keeping.
    5. Troublesome if filters are to be used or changed.
    6. Cannot be used if size expanding filter rings or rectangular filter holders are used.
    7. Difficult to take off, especially metallic hoods
    7. Ultra wide angle lenses have very short hoods that offer very little protection. (not a problem but lack of advantage)



    8.3 Lens stepping rings

    Filters that are larger than the lens front element is attached by a step up ring.
    Filters that are smaller than the lens front element is attached by a step down ring.
    Up and down refers to the change of size from the lens to the filters.

    This allow the use of incompatible filter size for the lens, which in some cases is used by people who want to use a single occasional filter for all lens sizes. UV filters used for protection are often attached to the lens on a long term basis and thus compatible sizes are used accordingly. However, for polarisers that is only used once in a while, and if cost is a concern, a single (largest size) polariser, say 77mm, can be used on 3 different lenses with front thread size of say 55mm, 67mm and 77mm, via 55-77mm and 67-77mm step up rings.

    Step down rings is not commonly used as it causes physical vignetting in most of the cases.

    Using the same polariser/other filters for different lens via different stepping rings is fine for slow pace use but not suitable for fast swapping of lens, as you need to detach the polariser from one lens to be attached on another lens, and you also need to change different rings on the polariser. On the other hand, if you use different size polarisers, one for each lens, you can always pre-attached the polariser if you consistently need to use the polariser in that occasion, but need to change into another lens for another focal length.



    8.4 Lens-filter series adaptors

    Quoted from dll927 at rangefinder.com, posted in 2006

    "Filters known as "series" are basically an older concept dating from the days when cameras had "slip-on" filter rings. The idea was that, by having the correct size of "slip-on" filter ring, you could use the "series" filter, which simply slipped into the ring., and you needed a "retaining" ring to hold it. In other words, there were no threads on the lens to accommodate filters. Nowadays it's considered better to buy filters for the largest-diameter lens you use, then use step-up or step-down rings for other lenses in your arsenal."

    .
    Last edited by zoossh; 18th August 2008 at 09:23 PM.

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    Default Re: DSLR newbie guide + Product/Price/Outlet List

    Maintainence of Lens


    Fungus in lens: how to check for it.

    As rephrased from and added onto account from Fotophilic,

    1. Inspect the exterior conditions of the lens to check for signs of previous impact or abrasion, and to note shaky parts.
    2. Inspect the front and rear surface to look for significant smudges.
    3. Open the aperture to the largest by pushing a lever on the lens rear and hold it against a light source to check for clarity.
    4. Close the aperture to the smallest and while doing that, check smooth movement of the blades.
    5. Make use of the contrast of the black colored blades to look for possible spots of fungus. Tilt it at various angles to see. Do the same to both rear and front of the lens. Check for suspicious things on the wall of the lens also.
    6. Use a bright LED or torchlight to add vision, if needed.
    7. Mount it on the camera, take a few shots at various aperture settings. Review the zoomed image on the LCD.

    .
    Last edited by zoossh; 19th May 2008 at 11:48 PM.

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