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Thread: Aperture

  1. #1

    Default Aperture

    hi guys
    i am reading this: http://en.wikipedia.org/wiki/Aperture
    and i have a few questions...


    the article states that "The photography term "one f-stop" refers to a factor of √2 (approx. 1.41) change in f-number, which in turn corresponds to a factor of 2 change in light intensity." and states that there are got f1.4 f2 f2.8 f4 f5.6 f8...

    Q1. (dslr) which means when we up 1 stop f2 becomes f2.8? correct?

    Q2. (dslr) my nikkor len is f3.5 - f5.6, how come the f3.5 is not anywhere on that scale? there is only f2.8 and the next stop is f4, how does f3.5 comes in?

    Q3. (pns) there are 2 f stop, one is on the len, Maximum aperture f/2.8 - f/3.5, but on my pns camera, the f appears from f3.2 - f8... how come got this difference? and which one is accurate? does that means anything from f3.5 onwards, it is non existence for that camrea?

    Q4. (pns) Focal length 5.8 - 58 mm (35 mm equivalent: 38 - 380mm). So for this PnS, do i need to multiply the crop factor to get the actual mm? or 38 is already factor in the crop factor?

    thanks!
    D90|10-24mm f3.5-4.5G|70-300mm VR f/4.5-5.6G|18-105mm VR f/3.5-5.6G|35mm f/1.8|SB700|MB-D80

  2. #2

    Default Re: Aperture

    1. correct, though the correct term should be stop down 1 stop..

    2. the f/2,2.8,4 are full 1 stop scales, f/3.5 is 1/3 stop from f/4..

    3. if your PnS has a manual mode, it should be able to open up fully, some modes don't allow it..

    4. 5.8-58mm is the actual physical focal length, the 35mm eq is already calculated for you so that it as that to approximate the angle of view..

  3. #3

    Default Re: Aperture

    Quote Originally Posted by J-Chan View Post
    1. correct, though the correct term should be stop down 1 stop..

    2. the f/2,2.8,4 are full 1 stop scales, f/3.5 is 1/3 stop from f/4..

    3. if your PnS has a manual mode, it should be able to open up fully, some modes don't allow it..

    4. 5.8-58mm is the actual physical focal length, the 35mm eq is already calculated for you so that it as that to approximate the angle of view..
    hmm... for question 2... does the camera follows f/2, f/2.8, f/4 or should it follow the lens f/3.5? or how should it be? i am a bit confused, can't test with my dslr for now, cos in office...

    for question 3, yup, only the camera, i can open up max 3.5 and min 8... but i thought the len is only from f3.5 - f5.6, so what happens outside this range? as in if the lens state f5.6... and in the camrea, i set f/8... so do i get f/5.6 or f/8?

    thank you for helping out :-)
    D90|10-24mm f3.5-4.5G|70-300mm VR f/4.5-5.6G|18-105mm VR f/3.5-5.6G|35mm f/1.8|SB700|MB-D80

  4. #4
    Senior Member giantcanopy's Avatar
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    Default Re: Aperture

    Quote Originally Posted by desertstrike View Post
    hmm... for question 2... does the camera follows f/2, f/2.8, f/4 or should it follow the lens f/3.5? or how should it be? i am a bit confused, can't test with my dslr for now, cos in office...
    it will follow the widest aperture setting labelled on the lens. Labelled at f3.5, you cannot make it shoot at any larger aperture e.g f2.8. ( yes the camera can bring the aperture to smaller sizes such as f4, f5.6, f8 etc .. the limit of the smallest size of the aperture is lens dependent )

    Quote Originally Posted by desertstrike View Post
    for question 3, yup, only the camera, i can open up max 3.5 and min 8... but i thought the len is only from f3.5 - f5.6 , so what happens outside this range? as in if the lens state f5.6... and in the camrea, i set f/8... so do i get f/5.6 or f/8?

    thank you for helping out :-)
    The f3.5 - f5.6 tells you what are the widest apertures available for the range of your zoom lens. For example if a zoom lens is 18-200mmf3.5-f5.6, it means widest aperture at 18mm is f3.5, and widest at 200mm is f5.6 (the rest of the focal lengths have their widest aperture sizes somewhere in between, this u need to refer to the lens manual ). But you can stop down the aperture even smaller, the limits of how small ur aperture can go for a particular lens u gotta check with the manual.
    ( alternatively u can try shooting and adjusting to see how small it can get )

    Ryan
    Last edited by giantcanopy; 3rd December 2008 at 01:26 PM.

  5. #5

    Default Re: Aperture

    just to add, the 1/3 stop scale goes something like f/2, 2.2, 2.5, 2.8, 3.2, 3.5, 4, ie finer steps

  6. #6
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    Default Re: Aperture

    there is an 1.4x different between each stop for f/ value. e.g.
    f/1.4 (x1.4) = f/2
    f/2.0 (x1.4) = f/2.8
    f/2.8 (x1.4) = f/4.0
    f/4.0 (x1.4) = f/5.6
    f/5.6 (x1.4) = f/8.0
    etc,
    do for f/3.5 the one stop different is f3.5 (x1.4) = f/4.9 (or roughly around this value). 2 stops is f/7 (or roughly around this value)
    Sony Alpha 700 hobbyist

  7. #7

    Default Re: Aperture

    Quote Originally Posted by giantcanopy View Post
    it will follow the widest aperture setting labelled on the lens. Labelled at f3.5, you cannot make it shoot at any larger aperture e.g f2.8. ( yes the camera can bring the aperture to smaller sizes such as f4, f5.6, f8 etc .. the limit of the smallest size of the aperture is lens dependent )



    The f3.5 - f5.6 tells you what are the widest apertures available for the range of your zoom lens. For example if a zoom lens is 18-200mmf3.5-f5.6, it means widest aperture at 18mm is f3.5, and widest at 200mm is f5.6 (the rest of the focal lengths have their widest aperture sizes somewhere in between, this u need to refer to the lens manual ). But you can stop down the aperture even smaller, the limits of how small ur aperture can go for a particular lens u gotta check with the manual.
    ( alternatively u can try shooting and adjusting to see how small it can get )

    Ryan

    okie, so i should only follow what is printed on the lens rite? no matter is smallest or largest
    hmm...

    i roughly remember that for PnS, my len biggest aperture is f2.8, however on camera, i can only step up to f3.2... maybe i need to double check...

    on the other hand, if the len on my PnS state smallest aperture at f3.5 but i can step down to f8... so any aperture smaller than f3.5, i.e. f5.6 do i get f/5.6(camera) or f3.5(on len)?
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  8. #8

    Default Re: Aperture

    Quote Originally Posted by J-Chan View Post
    just to add, the 1/3 stop scale goes something like f/2, 2.2, 2.5, 2.8, 3.2, 3.5, 4, ie finer steps
    okie, so do all camera able to adjust to this finer steps or only certain brand can?
    D90|10-24mm f3.5-4.5G|70-300mm VR f/4.5-5.6G|18-105mm VR f/3.5-5.6G|35mm f/1.8|SB700|MB-D80

  9. #9
    Senior Member giantcanopy's Avatar
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    Default Re: Aperture

    Quote Originally Posted by desertstrike View Post
    on the other hand, if the len on my PnS state smallest aperture at f3.5 but i can step down to f8... so any aperture smaller than f3.5, i.e. f5.6 do i get f/5.6(camera) or f3.5(on len)?
    You mean your lens aperture is largest at f3.5 not smallest.
    f4 / 5.6 / 8 etc are smaller apertures.

    At f3.5, you can step down to even smaller apertures to f8 for example.

    The aperture is an attribute of the lens, not the camera

    Ryan
    Last edited by giantcanopy; 3rd December 2008 at 02:03 PM.

  10. #10

    Default Re: Aperture

    Quote Originally Posted by giantcanopy View Post
    You mean your lens aperture is largest at f3.5 not smallest.
    f4 / 5.6 / 8 etc are smaller apertures.

    At f3.5, you can step down to even smaller apertures to f8 for example.

    The aperture is an attribute of the lens, not the camera

    Ryan
    er.. the range is f2.8 - f3.5...

    so i mean my aperture is smallest at f3.5 correct? or wrong? haha
    largest is ar f2.8 rite?

    so if the scale is:

    f1.4 ----- f2 ----- f2.8 ----- f4 ------ f5.6 ----- f8

    my aperture(len) is:

    ____________________2.8 - f3.5_____________________

    but my camera setting can go from:

    _______________________f3.2 --------------------- f8__

    so which one should i follow?

    sorry for the confusion...
    Last edited by desertstrike; 3rd December 2008 at 02:10 PM.
    D90|10-24mm f3.5-4.5G|70-300mm VR f/4.5-5.6G|18-105mm VR f/3.5-5.6G|35mm f/1.8|SB700|MB-D80

  11. #11
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    Default Re: Aperture

    an example of the lens as Tamron AF 18-270mm f/3.5-6.3
    Maximum aperture F3.5-6.3
    Minimum aperture F22-40 (not stated on the lens)
    so it means at the widest 18mm, the aperture is range from f/3.5-22, at most tele range 270mm, the aperture is range from f/6.3-40.

    so your f/2.8 - f/3.5 mean the lens has Maximum aperture f/2.8 at it widest end and Maximum aperture f/3.5 at it most tele end, while the minimum aperture is not stated.
    Sony Alpha 700 hobbyist

  12. #12

    Default Re: Aperture

    Quote Originally Posted by zcf View Post
    an example of the lens as Tamron AF 18-270mm f/3.5-6.3
    Maximum aperture F3.5-6.3
    Minimum aperture F22-40 (not stated on the lens)
    so it means at the widest 18mm, the aperture is range from f/3.5-22, at most tele range 270mm, the aperture is range from f/6.3-40.

    so your f/2.8 - f/3.5 mean the lens has Maximum aperture f/2.8 at it widest end and Maximum aperture f/3.5 at it most tele end, while the minimum aperture is not stated.
    oh, i think i am enlgihtened! thank you so much zcf!

    so how do u find the hidden minimun aperture if it is not stated?
    D90|10-24mm f3.5-4.5G|70-300mm VR f/4.5-5.6G|18-105mm VR f/3.5-5.6G|35mm f/1.8|SB700|MB-D80

  13. #13
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    Default Re: Aperture

    you can either try to close down the aperture on your lens when using the camera, or search through the lens manufacturer website, or on the original box/insert of the lens.
    Sony Alpha 700 hobbyist

  14. #14

    Default Re: Aperture

    i found out something:

    zcf, the tamron has
    Maximum aperture F3.5-6.3
    Minimum aperture F22-40
    on http://www.dpreview.com/lensreviews/...p5-6p3_vc_n15/

    i compared with nikkor 18-105mm dx vr
    Max/min aperture f/3.5-5.6
    on http://www.dpreview.com/news/0808/08...18-105lens.asp

    er... so max is 3.5 and min is 5.6? 0_o
    confused again...
    D90|10-24mm f3.5-4.5G|70-300mm VR f/4.5-5.6G|18-105mm VR f/3.5-5.6G|35mm f/1.8|SB700|MB-D80

  15. #15
    Moderator Octarine's Avatar
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    Default Re: Aperture

    Quote Originally Posted by desertstrike View Post
    so how do u find the hidden minimun aperture if it is not stated?
    Check the technical documentation of the lens, e.g. at websites of manufacturer. In real live the smallest aperture opening is irrelevant because is hardly used. Diffraction starts much earlier and will affect the sharpness of the image. If you need a smaller aperture to reduce the light further but you want to void diffraction then it's time for ND filters.
    Last edited by Octarine; 3rd December 2008 at 04:23 PM.

  16. #16

    Default Re: Aperture

    Quote Originally Posted by Octarine View Post
    Check the technical documentation of the lens, e.g. at websites of manufacturer. In real live the smallest aperture opening is irrelevant because is hardly used. Diffraction starts much earlier and will affect the sharpness of the image. If you need a smaller aperture to reduce the light further but you want to void diffraction then it's time for ND filters.
    oh ic, thanks Octarine, just curious how come dpreview states that max/min aperture together for the nikkor 18-105mm compared to the tamron 18-270mm
    D90|10-24mm f3.5-4.5G|70-300mm VR f/4.5-5.6G|18-105mm VR f/3.5-5.6G|35mm f/1.8|SB700|MB-D80

  17. #17
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    Default Re: Aperture

    Quote Originally Posted by desertstrike View Post
    i found out something:

    zcf, the tamron has
    Maximum aperture F3.5-6.3
    Minimum aperture F22-40
    on http://www.dpreview.com/lensreviews/...p5-6p3_vc_n15/

    i compared with nikkor 18-105mm dx vr
    Max/min aperture f/3.5-5.6
    on http://www.dpreview.com/news/0808/08...18-105lens.asp

    er... so max is 3.5 and min is 5.6? 0_o
    confused again...
    in this case, the website state wrongly or commonly f/3.5-5.6 as the max aperture for the wide to tele range, but didn't state the minimum aperture.
    Sony Alpha 700 hobbyist

  18. #18

    Default Re: Aperture

    Quote Originally Posted by zcf View Post
    in this case, the website state wrongly or commonly f/3.5-5.6 as the max aperture for the wide to tele range, but didn't state the minimum aperture.
    oh i see! okie thanks zcf!
    D90|10-24mm f3.5-4.5G|70-300mm VR f/4.5-5.6G|18-105mm VR f/3.5-5.6G|35mm f/1.8|SB700|MB-D80

  19. #19

    Default Re: Aperture

    i found le, the specs for 18-105mm hahaha, so both zcf and octarine are correct! thanks a lot!!!

    AF-S DX NIKKOR 18-105mm f/3.5-5.6G ED VR Specifications
    Focal length 18-105mm
    Maximum aperture f/3.5-5.6
    Minimum aperture f/22-38

    Lens construction 15 elements in 11 groups (with one ED glass element and one aspherical lens element)
    Picture angle 76 - 1520’
    Closest focus distance 0.45 m/1.48 ft. (throughout entire zoom range)
    Maximum reproduction ratio 0.2x (1/5)
    No. of diaphragm blades 7 (rounded)
    Filter attachment size 67mm
    Focusing Internal autofocus with built-in SWM and manual focus
    Diameter x length (extension from lens mount)
    Approx. 76 x 89 mm/3.0 x 3.5 in.
    Weight Approx. 420 g/14.8 oz.
    Supplied accessories 67mm snap-on front lens cap LC-67, Rear lens cap LF-1, Bayonet hood HB-32, Flexible lens pouch CL-1018
    http://www.nikon.com/about/news/2008/0827_nikkor_02.htm
    Last edited by desertstrike; 3rd December 2008 at 04:41 PM.
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  20. #20

    Default Re: Aperture

    another question ar guys, bear me me, just trying to learn :P

    i always thought that the aperture is on the len?

    but on 50D specification
    Aperture values
    • F1.0 - F91
    • 0.3 or 0.5 EV increments
    • Actual aperture range depends on lens used
    how come 50D has it aperture specs on body?
    it may sounds silly, but is aperture suppose to be on len or body?
    D90|10-24mm f3.5-4.5G|70-300mm VR f/4.5-5.6G|18-105mm VR f/3.5-5.6G|35mm f/1.8|SB700|MB-D80

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