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Thread: 1/Focal Length & handholdability

  1. #61

    Default Re: 1/Focal Length & handholdability

    Here goes again , no need for rocket science here.

    For Clockunder:

    Mr A. uses a 100mm lens on his 1Ds MKII to take a picture of a model lying on the beach such that her head touches the left side of the "viewfinder" and her legs touches the right side of the "viewfinder". He selects 1/100 secs for the shutter speed. He managed to get a sharp picture of the model.

    Mr B. seeing the outcome, wants to have the same result. But he is using a 350D and a 100mm lens. He dialed in 1/100 secs and stand at the same spot where Mr B. is. But hey, he can only see her shoulder to her thighs (which is just a crop). Therefore, he has to move back such that he gets the same composition as Mr A. He shoots using 1/100 secs and discovered that it's not as good. Is it because he stands further away? Well of course, the further away you are from the object, the shake is amplified and hence you would need to increase your shutter speed.

    With the above example, it simply means that when using a crop-factored camera, we actually unknowingly shoot from an equivalent distance of (crop factor X [the distance when using a 35mm camera]). In other words, read my underlined reiterations

    We take a picture wholly and think that it is a full-frame one even though we are using any crop factored camera. The crop factor is there and it's just that we do not think about it when we shoot.

    For Wind30:

    Pixel density, imo, just simply means how much you can enlarge for the most satisfactory print. Handshake only affects the physical size of the sensor. Both the 1Ds and the 1Ds MK2 are full-frame sensors. The only difference is that one is about 11 mega pixels while the other is 16 mega pixels. One can print larger than the other.

  2. #62
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    Default Re: 1/Focal Length & handholdability

    erm, distance from photographer to subject doesn't affect handshake. if it does, it mean we can't shoot landscape without a tripod! subject is miles away!
    if there is a increase of handshake chance, most probably it is due to pixel density and not distance.

  3. #63

    Default Re: 1/Focal Length & handholdability

    Quote Originally Posted by ExplorerZ View Post
    erm, distance from photographer to subject doesn't affect handshake. if it does, it mean we can't shoot landscape without a tripod! subject is miles away!
    if there is a increase of handshake chance, most probably it is due to pixel density and not distance.
    I did not say distance away from subject will affect handshake. What I meant was to shoot an object from distance X with a full-framed camera, you need to increase your distance when using a crop-factored one. And hence the increased distance, which is due to the crop factor, will magnify the shakes thru your viewfinder.
    Last edited by wong1979; 9th February 2007 at 01:01 AM.

  4. #64

    Default Re: 1/Focal Length & handholdability

    Quote Originally Posted by wong1979 View Post
    Here goes again , no need for rocket science here.
    For Wind30:

    Pixel density, imo, just simply means how much you can enlarge for the most satisfactory print. Handshake only affects the physical size of the sensor. Both the 1Ds and the 1Ds MK2 are full-frame sensors. The only difference is that one is about 11 mega pixels while the other is 16 mega pixels. One can print larger than the other.
    That is the point. If you want to enlarge bigger, you have to handhold better. Therefore pixel desity up -> enlargement up -> handholdability down. Example for, 11 meg sensor and 16 meg sensor, the 16 meg sensor can print bigger but when you print bigger you resolve more details and previously unnoticed handshake blur may become apparent.

  5. #65

    Default Re: 1/Focal Length & handholdability

    Quote Originally Posted by Clockunder View Post
    I would not want to point out the errors and mistakes of others directly but just to present my logical answers. Otherwise, I would have a lot to explain how and where their errors and mistakes are.
    I, on the other hand, will point out exactly what errors and mistakes you have.

    You have made the ASSUMPTION in your arguement that both sensor has the same pixel density which is not true for most sensors out there present.

    (use simpler numbers to illustrate)
    your arguement is valid is you are comparing 1 and 2
    1) 20meg sensor with crop of 1
    2) 5meg sensor with a crop of 2.
    3) 10 meg sensor with a crop of 2.

    In comparing sensor 1 and 2, you are right, as if you crop away the outer portions of sensor 1, you get EXACTLY the same image as sensor 2.

    In real life, cropped sensor often has higher pixel density similar to sensor 3. So if you cropped sensor 1 away you end up with a 5 meg jpeg compared to 10 meg jpeg from sensor 3. NOT THE SAME PICTURE. In a 10 meg jpeg, you can resolve much more fine details and thus see finer hand-shake than a 5 meg jpeg.

    I hope this is clear to you now.
    Last edited by wind30; 9th February 2007 at 09:18 AM.

  6. #66
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    Default Re: 1/Focal Length & handholdability

    Quote Originally Posted by wong1979 View Post
    I did not say distance away from subject will affect handshake. What I meant was to shoot an object from distance X with a full-framed camera, you need to increase your distance when using a crop-factored one. And hence the increased distance, which is due to the crop factor, will magnify the shakes thru your viewfinder.
    below quote from you.
    Well of course, the further away you are from the object, the shake is amplified and hence you would need to increase your shutter speed.

  7. #67
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    Default Re: 1/Focal Length & handholdability

    I guessed a lot of things start coming in when ppl lose focus on the topic.

    I only want to address point 1 relating to the 1/f for hand shakability.

    In due optic science, the answer is: The crop factor does not matter.
    Remember, we are only going to address one variable: THE HANDSHAKE.

    So with a certain shutterspeed, the hand shake is going to be the same for a certain focal length. That part takes part in the light path, etc...

    So the amount of light, the amount of deviated path of lights variables (from the handshake) stays the same when you use the same lens, all same condition on different bodies.

    The sensor size only differs in detacting how much are of those light that came thru.

    Like I am fat, I go suntan, I get more total skin area tan. You skinny you go tan, you get lesser total area tan.

    We both get tanned based on quality of our skin and the amount of sunlight and duration. We get the same sunrays!

    Crop factor only enlarges themselves digitally on prints as they have to magnify to be a 35mm film Equivalent. They can stay they own way, but its just that the industry merely wanted a standards so that ppl can have more uniformity (Well, four thirds system is trying to set their own standards anyway)

    If we are addressing ONLY HANDSHAKE, yes, the same shutterspeed will give you the same shake.

    If you use higher Megapixels, its only naturally that all flaws gets Magnified. This is not only to handshake but to abberations, softness of lower grade lens, etc etc...
    Andy Ang :lovegrin: - "A Photo speaks a thousand words. Have you spoken today?"
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  8. #68
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    Default Re: 1/Focal Length & handholdability

    Quote Originally Posted by Andy Ang View Post
    I guessed a lot of things start coming in when ppl lose focus on the topic.

    I only want to address point 1 relating to the 1/f for hand shakability.

    In due optic science, the answer is: The crop factor does not matter.
    Remember, we are only going to address one variable: THE HANDSHAKE.

    So with a certain shutterspeed, the hand shake is going to be the same for a certain focal length. That part takes part in the light path, etc...

    So the amount of light, the amount of deviated path of lights variables (from the handshake) stays the same when you use the same lens, all same condition on different bodies.

    The sensor size only differs in detacting how much are of those light that came thru.

    Like I am fat, I go suntan, I get more total skin area tan. You skinny you go tan, you get lesser total area tan.

    We both get tanned based on quality of our skin and the amount of sunlight and duration. We get the same sunrays!

    Crop factor only enlarges themselves digitally on prints as they have to magnify to be a 35mm film Equivalent. They can stay they own way, but its just that the industry merely wanted a standards so that ppl can have more uniformity (Well, four thirds system is trying to set their own standards anyway)

    If we are addressing ONLY HANDSHAKE, yes, the same shutterspeed will give you the same shake.

    If you use higher Megapixels, its only naturally that all flaws gets Magnified. This is not only to handshake but to abberations, softness of lower grade lens, etc etc...
    yes, you made the point, Pixel Density, but most of the time it is related to cropped factor as well. those smaller sensor usually have a much higher pixel density compare to even the 1DsMkII 16.7MP.
    A 10MP APS-C sensor have slightly higher density as compared to the 1DsMkII.

  9. #69

    Default Re: 1/Focal Length & handholdability

    This is for those who have difficulty following logical thinking in words without any pictures for illustrations.

    Comparison between the 2 images from different sensor sizes cameras where all technical aspects as follows are the same :
    a) same lens at the same focal length (e.g. 50mm)
    b) same shooting distance (e.g 5m)
    c) same aperture
    d) same shutter speed (e.g. 1/50)
    e) same amount of physical handshake

    Pictures below are just for illustration of the logic and of course are not taken by different cameras at the settings cited as example.

    A person wants a picture of the composition with the same DOF above taken by the 1.6x crop factor camera at 5m at 50mm. He has 2 cameras : a full frame and a 1.6x crop factor camera.

    1) Exactly the same physical images that falls on the image sensors

    Full frame (36 x 24mm) :


    1.6x crop factor camera (22.5 x 15mm)



    Comparison :



    2) Magnify both images by 6.77x in length or 45.8x in area and then print them on paper.

    Full frame (9.6” x 6.4” paper size)


    1.6x crop factor camera (6” x 4” paper size)
    Last edited by Clockunder; 10th February 2007 at 08:09 AM.

  10. #70

    Default Re: 1/Focal Length & handholdability

    3) Use a pair of sisscors and cut the full frame picture along the inner small rectangle which measures 6” x 4”



    4) Exactly the same picture as the one from the 1.6x crop factor camera in all aspects!

    Crop picture from Full frame (6” x 4”) :



    This is exactly the picture the shooter wanted as stated in the beginning of the previous post.

    They are exactly the same picture in all aspects :
    a) same lens at the same focal length (e.g. 50mm)
    b) same shooting distance (e.g 5m)
    c) same aperture
    d) same shutter speed (e.g. 1/50)
    e) same amount of physical handshake
    f) same composition
    g) same angle of view
    h) same magnifiction factor 6.77x in length or 45.8x in areas from their original physical image sizes
    i) same DOF (just in case some people don't understand why the DOF is the same even when different sensor sizes were used here : DOF calculation is based on assumed magnification needed to achieve a certain viewing size and so different DOFs for different sensor sizes. But here, the magnification is the same 6.77x in length and so the DOF is the same).

    5) So the same shutter speed is required to avoid handshake blur in the pictures above. So if it is 1/50 for the full frame, it is also 1/50 for the 1.6x crop factor camera in the above.

    6) As we can clear see from the guideline (1/focal length), the same guideline applies for different shooting distances and different composition. So when the above shows that it's 1/50 for the 1.6x crop factor camera at 5m, it's also 1/50 if he stands further away at 8m for the same 50mm lens.

    To understand why the guideline is the same for 5m, 8m, 10m, 20m, etc. (i.e. different compositions), you need to understand how the actual physical image is affected by handshake and recorded on the image sensor. It's obvious that the guideline never stipulate different shutter shutter for different shooting distances. If not, it would have been something like this 1/[focal length x (shooting distance/Y)] where Y is a constant so that it will be exactly 1/focal length if the shooting distance=Y. If further, then a faster shutter speed is necessary. E.g. if Y=5m : Then it will be 1/50 for 5m, 1/80 for 8m, 1/100 for 10m and so on for 50mm. If a person understands all these, then he would not insist that it is 1/80 for 8m even though it's 1/50 at 5m by arguing that a further shooting distance is necessary to achieve the same composition.

    7) It is therefore obvious that it is illogical to say that their minimum shutter guidelines to avoid handshake blur should be different for different sensor sizes.

    (p.s. The illustration should have clearly shown why the above comparison is the best and not still using the need to stand further or nearer away to achieve the same composition to justify a different guideline to avoid handshake blur. The technical aspects are 100% the same for the above comparison. Even in the guideline 1/focal length, it does not say that the shutter speed have to be different for different shooting distance and composition. So the guideline for the 1.6x crop factor camera is the same for 5m away and 8m away and it's illogical to say that you have to use a faster 1/80 shutter speed at 8m to avoid handshake blur when the above clearly shows that 1/50 is ok for 5m. You can find that most people and websites on the internet say factoring the crop factor in. But they're mostly monkey see, monkey do. Use your own thinking and follow logically, you will find that the real world in practice is more like there is no need to factor in the crop factor. There are many people who proudly proclaim that they can shoot handheld easily at at least 1 stop below what they thought is the guideline which factors in a 1.5x crop factor without realising that most people can just shoot at 1/actual focal length.)
    Last edited by Clockunder; 10th February 2007 at 09:04 AM.

  11. #71
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    Default Re: 1/Focal Length & handholdability

    but the thing is you miss out the pixel density, try resizing the fullframe to the same size as the cropped photos, the fullframe should give you a sharper image under the same condition. (provided both have tiny bit of blur, if they are sharp both will give sharp images anyway)

    yes, your crop is correct, but that is provided the pixel density of the fullframe and cropped sensor are exactly the same. (eg 16MP on FF and 8MP on a 1.5x cropped sensor or 4MP on a 4/3rd sensor, hope i didn't get the area of each sensor wrong.)
    Last edited by ExplorerZ; 10th February 2007 at 10:19 AM.

  12. #72
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    Default Re: 1/Focal Length & handholdability

    If by your logical thinking, then the information on the Pentax website is wrong?
    http://www.digital.pentax.co.jp/en/s...ch/vol_13.html

    From my understanding, not factoring individual handholding ability, the crop factor has to be factored in. The angle of view of a 50mm standard lens on a full frame changes to a short tele 75mm on a 1.5x, an 80mm on a 1.6x and 100mm on a 2x crop factor camera. Obviously image magnification is increased and to compensate for handshake, the rule must factor in the crop factor. Anytime image magnification increases (as in macro photography as well), the risk of hanshake increases.

    Discussion of pixel density, image distance are irrelevant. Actually I am puzzled why there is even a need to discuss about cropping the image. They are not exactly the same because you have cropped an image from a full frame camera to simulate the angle of view of a cropped factor camera. If you used a 50mm on a FF to get the picture, to get the same exact image, the cropped factor camera would have to move backwards to get the same angle of view. Perspective, DOF is not going to be the same.

  13. #73
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    Default Re: 1/Focal Length & handholdability

    here is a good read from one of the birder forum especially the last few post of page1.

  14. #74

    Default Re: 1/Focal Length & handholdability

    actual shake is one thing, visible shake is another. there's no such thing as zero shake, just how visible it is. when you crop a picture, to get the same size print, you need to magnify it more. you will magnify the shake, so that even if the amount the camera physically shook is the same, the amount of shake visible on the print is more.

    so when we use this guide for shake, are we more interested in the actual shake or the visible shake? of course the visible one lah, since we're looking at the picture. so, yes, take the crop factor into account.

    p.s.
    i've noticed that i can manage slower shutter speeds with my prosumer than my dlsr. but i suspect this has to do with other factors, such as the weight of the camera, as well as lack of mirror slap on the prosumer.

  15. #75

    Default Re: 1/Focal Length & handholdability

    Quote Originally Posted by Clockunder View Post
    This is for those who have difficulty following logical thinking in words without any pictures for illustrations.
    this is a good idea let me give it a go.

    ok let's say one day i decide that i'm sick of shining torchlight at a wall. so i take a picture of it instead.
    i post it online for my friends to see, at 600x400 size. here it is:



    my friend thinks wah! how cool! so he decides to take a picture of the same wall. he stands in the same place as me (because cannot change distance, that would be confusing ), uses the same actual focal length lens, and uses the same exposure settings.

    but because he has a point and shoot with a tiny sensor, the final image is cropped, and the actual image only shows the centre of the image (the bright part):



    as clockunder has already pointed out, the actual camera shake is the same in both shots (of course lah, it's the same shot mah). my friend posts his picture, also at 600x400:



    *edit* i think maybe original meaning of what i said was unclear, since it seems a lot of singaporeans don't understand sarcasm. basically, what i've just done is simulate the effect of using a 5x crop camera with the same settings as a fullframe one. just check out the difference in the first and third pix. the first one is a little soft, but as a record shot, still acceptable (subject matter aside lah, hehe). the last one... er with that kind of handshake effect you dare to show ppl meh?

    p.s. the blurring effect in the pix is from handshake yah, not from lack of lens or sensor resolution. the last picture is a 100% crop, not enlarged any further
    Last edited by pai; 10th February 2007 at 07:38 PM.

  16. #76
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    Default Re: 1/Focal Length & handholdability

    Wong1979 brought up a very interesting topic for discussion. If I look at it at a different angle, that is whether the distant of the focused subject is affected by hand shake at a different degree for a given focal length and shutter speed. Out of curiosity, I carried out an experiment:

    Using 10D, 100mm focal length, 1/25.

    My distant from "Harvest Times" is 5m


    My distant from "Harvest Times" is now 8m


    The conclusion is that I can capture a clear shot with 1/25s at 5m from the subject. The same can not be done when the same subject is 8m away, both at 100mm focal length.



  17. #77

    Default Re: 1/Focal Length & handholdability

    clockunder,

    I give up. Actually you have to review the way you think and analyse things.

    I already point out EXACTLY the ASSUMPTION that you have made in your arguement and why it is not valid most of the time. And yet you totally ignored my post and just reiterated the same flawed arguement.

    In the face of overwhelming evidence,

    1) pentax, olympus BOTH have officially stated their stand in that the crop factor matters. I am sure canon and nikon does too but am too lazy to check
    2) you still havenot answered my question yet. CAN YOU HANDHOLD a 50mm lens on a 5 meg sensor with a crop factor of 100. YES OR NO?

    you still cannot accept the answer. Ok lor, you win.

  18. #78

    Default Re: 1/Focal Length & handholdability

    hm. no new responses. is the debate settled?

  19. #79

    Default Re: 1/Focal Length & handholdability

    Hi Pai, I thank u for ur participation. I actually thought u did an actual test Even though not, I see ur good intention.

    To L.lee:

    Your test is not what I mean. Guess I have confused u by talking about distance. Distance from subject don't affect your handshake. If you are to crop the one at 8m, say at 600 X 400, against the one at 5m. It shd be the same. When I talk about distance, I actually meant that when one uses a crop-factored camera, we are actually shooting further away when compared to a full-frame counterpart using the same focal length. And hence, the further away, the handshake will be amplified on your image output.
    Last edited by wong1979; 13th February 2007 at 07:04 AM.

  20. #80

    Default Re: 1/Focal Length & handholdability

    Quote Originally Posted by L.Lee View Post
    Wong1979 brought up a very interesting topic for discussion. If I look at it at a different angle, that is whether the distant of the focused subject is affected by hand shake at a different degree for a given focal length and shutter speed. Out of curiosity, I carried out an experiment:

    Using 10D, 100mm focal length, 1/25.

    My distant from "Harvest Times" is 5m


    My distant from "Harvest Times" is now 8m


    The conclusion is that I can capture a clear shot with 1/25s at 5m from the subject. The same can not be done when the same subject is 8m away, both at 100mm focal length.


    You only did 1 test and you believe it is conclusive? Sloppy and unscientific.

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