Page 1 of 2 12 LastLast
Results 1 to 20 of 25

Thread: Aperture + Shutter Speed Relationship.

  1. #1

    Default Aperture + Shutter Speed Relationship.

    Hi, i've juz got into photography a few months back and have read up a little regarding these features. Been shooting alittle with my PnS A95 which has some control of the aperture and shutter speed.. Now that i've gotten a nikon d50, i was wondering if anyone can put the relations in simple terms coz im getting quite confused abt them..

    Aperture + shutter speed = Exposure level ?

    does the aperture affects the depth of field ?
    what does it exactly do ?

    I basically know how to control the shutter speed to get the kind of photos i want but im not exactly sure abt settings apertures. Appreciate if anyone can supply me the answers or links to my clarify my doubts. TIA

  2. #2
    Senior Member +evenstar's Avatar
    Join Date
    Jan 2004
    Location
    Singapore / United Kingdom
    Posts
    5,655
    eat. drink. shoot

  3. #3

    Default Re: Aperture + Shutter Speed Relationship.

    Quote Originally Posted by shadie
    Hi, i've juz got into photography a few months back and have read up a little regarding these features. Been shooting alittle with my PnS A95 which has some control of the aperture and shutter speed.. Now that i've gotten a nikon d50, i was wondering if anyone can put the relations in simple terms coz im getting quite confused abt them..

    Aperture + shutter speed = Exposure level ?

    does the aperture affects the depth of field ?
    what does it exactly do ?

    I basically know how to control the shutter speed to get the kind of photos i want but im not exactly sure abt settings apertures. Appreciate if anyone can supply me the answers or links to my clarify my doubts. TIA
    Think of the exposure like trying to fill a pail using a tap. The aperture is like the tap control and the size of the pail is like your film speed. To fill the pail, if you open the tap bigger, it will fill faster. If you close the tap such that the flow is half, it will take double the time for you to fill the pail.

    About DoF, yes, aperture will affect DoF. This is due to the physics of optics. If you wear spectacles, and you try not wearing them , you will find that in the day you could probably see clearer and the vision becomes worse at night. This is because in the day, the iris closes to reduce the amount of light reaching the retina, the aperture becomes smaller, and the image is sharper over a wider range of distances.

  4. #4

    Default Re: Aperture + Shutter Speed Relationship.

    Thanks for the links +evenstar. The second link gives me more idea of what how to control the exposure.

    Hmmmm... for the pail concept. Is the film speed u're refering to the ISO ? alittle unsure of what ur refering to. Erm, do smaller aperture usually used for group photos? for eg if i wanna take a landscape pic, i use smaller aperture ? Correct me if im wrong. Thanks

  5. #5
    Member
    Join Date
    Feb 2006
    Location
    Singapore East
    Posts
    125

    Default Re: Aperture + Shutter Speed Relationship.

    Quote Originally Posted by shadie
    Thanks for the links +evenstar. The second link gives me more idea of what how to control the exposure.

    Hmmmm... for the pail concept. Is the film speed u're refering to the ISO ? alittle unsure of what ur refering to. Erm, do smaller aperture usually used for group photos? for eg if i wanna take a landscape pic, i use smaller aperture ? Correct me if im wrong. Thanks
    if its a big group maybe u got to use a smaller aperture to ensure that everyone's faces are in focus.. but it actually depends on how u want the pic taken

  6. #6
    Deregistered
    Join Date
    Dec 2002
    Location
    Planet Nikon
    Posts
    21,905

    Default Re: Aperture + Shutter Speed Relationship.

    Get the book "Understanding Exposure". It will help.

  7. #7

    Default Re: Aperture + Shutter Speed Relationship.

    Quote Originally Posted by shadie
    Thanks for the links +evenstar. The second link gives me more idea of what how to control the exposure.

    Hmmmm... for the pail concept. Is the film speed u're refering to the ISO ? alittle unsure of what ur refering to. Erm, do smaller aperture usually used for group photos? for eg if i wanna take a landscape pic, i use smaller aperture ? Correct me if im wrong. Thanks
    It really depends. The focusing becomes shallower when the distance is nearer and if you use longer focal length lenses. For landscape, it also depends on how much you want to be in focus. When in doubt you can use the depth of field preview. What you see through the viewfinder (if you use an SLR) is exactly what you will get if you're using the maximum aperture. So if you close the aperture down, you will need to use the DoF preview button.

    Generally if you think the lighting situation is not good and you need more light and want to prevent camera shake, you may want to use the biggest available aperture unless you really need the depth of field. You may have to compromise depending on the lighting situation itself.

    Oh yes. I was referring to ISO when I mentioned film speed.
    Last edited by lsisaxon; 26th March 2006 at 11:19 PM.

  8. #8

    Default Re: Aperture + Shutter Speed Relationship.

    Quote Originally Posted by Jacobyeo
    if its a big group maybe u got to use a smaller aperture to ensure that everyone's faces are in focus.. but it actually depends on how u want the pic taken
    been trying to get a more focused group photo. Will try it out. thanks

  9. #9

    Default Re: Aperture + Shutter Speed Relationship.

    Quote Originally Posted by espn
    Get the book "Understanding Exposure". It will help.
    Who's the author of the book ? Any idea how much it cost ? TIA

  10. #10

    Default Re: Aperture + Shutter Speed Relationship.

    Quote Originally Posted by lsisaxon
    It really depends. The focusing becomes shallower when the distance is nearer and if you use longer focal length lenses. For landscape, it also depends on how much you want to be in focus. When in doubt you can use the depth of field preview. What you see through the viewfinder (if you use an SLR) is exactly what you will get if you're using the maximum aperture. So if you close the aperture down, you will need to use the DoF preview button.

    Generally if you think the lighting situation is not good and you need more light and want to prevent camera shake, you may want to use the biggest available aperture unless you really need the depth of field. You may have to compromise depending on the lighting situation itself.

    Oh yes. I was referring to ISO when I mentioned film speed.
    Im using a D50. Dont think it have the DoF preview button..

    correct me if im wrong... biggest aperture being F2.0 as compared to F36 ?

  11. #11

    Default Re: Aperture + Shutter Speed Relationship.

    Quote Originally Posted by shadie
    Im using a D50. Dont think it have the DoF preview button..

    correct me if im wrong... biggest aperture being F2.0 as compared to F36 ?
    Yes.. bigger aperture is the one with a smaller f-number. No DoF preview is fine, I seldom use mine anyway.. All you need to know is that if you want more range of distance to be sharp, then use a smaller aperture. For a group photo, if the distances of the people doesn't vary very much, it shouldn't matter if you use a good lens where the corner and centre sharpness is about the same. For cheaper lenses, the corners might not be very sharp and closing the aperture will definitely help. Also, the field correction of the lenses will also determine if the subject distance is the same at centre and at corner and if it's just the plane distance from the centre or the direct distance of the subject at the corner to the lens. It all depends on the lens construction.

  12. #12

    Default Re: Aperture + Shutter Speed Relationship.

    Quote Originally Posted by lsisaxon
    Yes.. bigger aperture is the one with a smaller f-number. No DoF preview is fine, I seldom use mine anyway.. All you need to know is that if you want more range of distance to be sharp, then use a smaller aperture. For a group photo, if the distances of the people doesn't vary very much, it shouldn't matter if you use a good lens where the corner and centre sharpness is about the same. For cheaper lenses, the corners might not be very sharp and closing the aperture will definitely help. Also, the field correction of the lenses will also determine if the subject distance is the same at centre and at corner and if it's just the plane distance from the centre or the direct distance of the subject at the corner to the lens. It all depends on the lens construction.
    Juz came back from shooting at sg river. Tried out a few features and settings with the suggestions given. Gonna post at APAD section after i learn how to PS/crop/resize my work. Thanks all for the tips and links. Pretty much enjoyed my first day out shooting
    Last edited by shadie; 27th March 2006 at 11:19 PM.

  13. #13
    Deregistered
    Join Date
    Dec 2002
    Location
    Planet Nikon
    Posts
    21,905

    Default Re: Aperture + Shutter Speed Relationship.

    Quote Originally Posted by shadie
    Who's the author of the book ? Any idea how much it cost ? TIA
    Bryan Peterson, no more than $30 IIRC. It's a worthwhile book to invest in.

  14. #14

    Default Re: Aperture + Shutter Speed Relationship.

    Quote Originally Posted by espn
    Bryan Peterson, no more than $30 IIRC. It's a worthwhile book to invest in.
    Cool. Will check out the library first if they have it or not. Then probably buy it after i have some spare cash. TA

  15. #15

    Default Re: Aperture + Shutter Speed Relationship.

    I tried finding in some libraries already, but got no "understanding exposure" leh. Anyone knows where have? National Library? Or any bookshop got sell? And how much huh? Cus I scared no money..heh heh..

  16. #16
    Senior Member
    Join Date
    Aug 2005
    Location
    Singapore, CanonGraphers.org
    Posts
    3,157

    Default Re: Aperture + Shutter Speed Relationship.

    Quote Originally Posted by wanhjb
    I tried finding in some libraries already, but got no "understanding exposure" leh. Anyone knows where have? National Library? Or any bookshop got sell? And how much huh? Cus I scared no money..heh heh..
    You can also try finding some on the internet..I'll send some good sites to you later..

  17. #17

    Default Re: Aperture + Shutter Speed Relationship.

    try borrowing any book from the library....will give u lots of information on that


    cheers

  18. #18
    Member
    Join Date
    Apr 2004
    Location
    In my own world
    Posts
    1,314

    Default Re: Aperture + Shutter Speed Relationship.

    Hope my layman terms are correct.

    Big hole (small f value) + slow shutter
    Small hole (big f value) + fast shutter

    The above 2 allows same amount of light entered into the camera. Imagine you have a big mouth but eats slow and another small mouth but eats very quickly, both of u finished the food at the same time.

    Another term you need to know is DOF. Though you get the same amount of light, big F will gives shallower depth of field than a small f.

    Scenario A : You focused on object A, object slighly behind or slight infront of A will not be perfectly focused. All things further or nearer will be very much out of focus. This is called shallow DOF, good for getting a blurring background.

    Scenario B : You focused on object A, object slighly behind or slight infront of A will be perfectly focused. All things further or nearer will be very focus too, depending the DOF you had preset. This is called deep DOF, good for getting all the details.

    Take note also, lens had its "sweet spot", where it actually had its so called optimum sharpness. Most lens had it at F8.

    Use my guide as a reference only.

    Guess i'm bored.
    Last edited by rainman; 29th March 2006 at 08:49 PM.

  19. #19
    Senior Member zoossh's Avatar
    Join Date
    Nov 2005
    Location
    Singapore
    Posts
    8,725

    Default Re: Aperture + Shutter Speed Relationship.

    Quote Originally Posted by shadie
    Hi, i've juz got into photography a few months back and have read up a little regarding these features. Been shooting alittle with my PnS A95 which has some control of the aperture and shutter speed.. Now that i've gotten a nikon d50, i was wondering if anyone can put the relations in simple terms coz im getting quite confused abt them..

    Aperture + shutter speed = Exposure level ?

    does the aperture affects the depth of field ?
    what does it exactly do ?

    I basically know how to control the shutter speed to get the kind of photos i want but im not exactly sure abt settings apertures. Appreciate if anyone can supply me the answers or links to my clarify my doubts. TIA
    let me try my go in explaining the way i understand it. i'm sure many had explained before but i got my way of understanding too, so just to share.

    aperture opening size + shutter opening duration = amt of light onto sensor/film

    the larger the opening, the more light enters.
    the longer the opening remains open, the more light enters.
    when the opening size and opening duration are sufficient big and long, the amt of light will be adequate and will give the desired exposure for that picture.
    people usually use the analogy of a pail or a tap to describe it. as the aperture opening size and the shutter opening duration are reciprocal to each other, one of them goes up and the other goes down, eventually put together will even out to give the same amt of light.

    however when on practice, the confusion starts as figures used are reciprocals of the above equation.

    aperture opening size + shutter opening duration = amt of light onto sensor/film
    1/aperture opening size + 1/shutter opening duration = 1/ISO
    f/stop no. + shutter speed = ISO

    when the aperture opening size area is decreased by n times (linearly 1, 2, 3, 4, 5....), the diameter is also decreased by a per-calculated protocol in which the denominator is the no. of times the diameter is decreased (if i didn't remember wrongly it goes f/1, f/1.4, f/2, f/2.8, f/4, f/5.6 ....). so while the aperture opening decreases (less light in), the f/stop number increases (less light in). note the reverse relationship.

    when the shutter opening duration is decreased, i.e. faster, the time duration goes this way, 1sec, 1/2sec, 1/4sec, 1/8sec, 1/15sec, 1/30sec, 1/60sec..... on your camera, the time is recorded as 1, 2, 4, 8, 15, 30, 60 (most of the time as newbie we shoot at shutter speed less than 1 sec) .... in contrast to those more than 1 sec, i.e. 1sec, 2sec, 4sec, 8 sec are recorded as 1", 2", 4", 8"..... note that like the aperture opening, as the shutter duration decreases, the no. of times of division/splitting of a second increases, and the no. (without the ") will be becoming larger and larger. the no. of times of splitting of a second is the speed, the more it splits, the shorter the duration (less light in), the higher the speed (less light in) and the greater the number on the shutter speed on the camera. so this is again a reverse relationship.

    ISO ratings give the sensitivity of the sensor/film to the amt of light. a low ISO rating has a low sensitivity and requires more light to give an output that looks bright enough. a high ISO rating has a high sensitivity and requires less light to give an output that looks bright enough. note again the reverse relationship, low ISO = more light required, high ISO = less light required.

    now digest the reverse relationship for the above 3 things and make a note always to differentiate aperture size and f/stop no. that they are reverse, and differentiate shutter duration and shutter speed that they are reverse.

    aperture opening size + shutter opening duration = amt of light onto sensor/film
    1/aperture opening size + 1/shutter opening duration = 1/ISO
    f/stop no. + shutter speed = ISO

    now note the relationship between the 1st two elements on the left side of equation and the right side of equation.....let me reverse the equation.

    ISO = f/stop no. + shutter speed

    from the understanding of the equation,
    when we increased the ISO, we can afford to increase f/stop no and the shutter speed. i.e. if we increased ISO sensitivity from 200 to 1600, (3 stop difference, 200 to 400, 400 to 800, 800 to 1600), we can increase the f/stop no. and the shutter speed by 3 times too, maybe 3 times for the f/stop no. or 3 times the shutter speed, or 2 times the f/stop no plus 1 times the shutter speed, vice versa.

    from the understanding from the amt of light coming in, go back to the first equation and look at the last equation,

    aperture opening size + shutter opening duration = amt of light onto sensor/film

    more light in thru bigger hole + more light in with longer duration = more light in total

    ISO = f/stop no. + shutter speed

    less light required at higher ISO = less light in with higher f/stop no. + less light in with higher shutter speed

    i hope the way i understand as a newbie, with various reading and attending lesson and the understanding exposure book, can help you to understand. the first block to the newbie is the up and down seems to refer to different things and are so confusing, so i hope you can get a better idea of the up and down of the setting....

    for the experts, if there is any error in my explaination, pls correct me too....

  20. #20

    Default Re: Aperture + Shutter Speed Relationship.

    Quote Originally Posted by zoossh
    when the aperture opening size area is decreased by n times (linearly 1, 2, 3, 4, 5....), the diameter is also decreased by a per-calculated protocol in which the denominator is the no. of times the diameter is decreased (if i didn't remember wrongly it goes f/1, f/1.4, f/2, f/2.8, f/4, f/5.6 ....). so while the aperture opening decreases (less light in), the f/stop number increases (less light in). note the reverse relationship.
    The area is not increased or decreased linearly. It has to be either doubled or half to increase and decrease by a stop respectively. So if area is doubled or half, the diameter will be multiplied or divided by square root of 2 respectively... which is why the numbers like 1.4, 2.8, 5.6 etc comes in. Square root of 2 is approximately 1.4.
    Last edited by lsisaxon; 30th March 2006 at 03:57 PM.

Page 1 of 2 12 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •