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Thread: Shallow DOF

  1. #1

    Default Shallow DOF

    which would be the method to get a shallow DOF? smaller aperture or faster shutter speed?

  2. #2
    Member/Tangshooter Redsun's Avatar
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    Default Re: Shallow DOF

    smaller aperture value

  3. #3
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    Default Re: Shallow DOF

    Quote Originally Posted by boredphuck View Post
    which would be the method to get a shallow DOF? smaller aperture or faster shutter speed?
    Faster shutter speed don't contribute to DOF

    Apperture size and focal length do.

    http://www.dofmaster.com/dofjs.html
    Sony Alpha 700 hobbyist

  4. #4
    Senior Member dorts's Avatar
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    Default Re: Shallow DOF

    Distance affects the DOF too.

  5. #5

    Default Re: Shallow DOF

    Generally, the smaller the f-stop number, the shallower the DOF for a given distance to object.

  6. #6

    Default Re: Shallow DOF

    thank u guys for the help. going to play around with the settings again tonite. thanks a million again!

  7. #7
    Senior Member zac08's Avatar
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    Default Re: Shallow DOF

    Quote Originally Posted by Redsun View Post
    smaller aperture value
    Eh.... you have to be careful with such phrasing, else they may mistake using f11 or f16 as a smaller aperture value.

    A large aperture in correlation to the lens focal length will give you a nicer blur of the background as well as foreground. Often it will mean as big as f1.4 to f1.8 for a short focal length of 50mm. As the focal length increases, you can use smaller apertures such as f5.6 or f8 to the same effect.
    Michael Lim
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  8. #8

    Default Re: Shallow DOF

    ok. i'm abit lost liao.

  9. #9
    Senior Member dorts's Avatar
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    Default Re: Shallow DOF

    Small aperture means a F stop of like f/22 which means deeper DOF. Large aperture means a F stop of maybe f/2 which will give you your shallow DOF.

  10. #10
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    Default Re: Shallow DOF

    Depth of field formulae

    Hyperfocal Distance
    Let f be the lens focal length, N be the lens f-number, and c be the circle of confusion for a given image format. The hyperfocal distance H is given by
    H=f2/Nc

    Moderate-to-large distances
    Let s be the distance at which the camera is focused (the “subject distance”). When s is large in comparison with the lens focal length, the distance DN from the camera to the near limit of DOF and the distance DF from the camera to the far limit of DOF are
    Dn=Hs/(H+s), Ds=Hs/(H-s)

    When the subject distance is the hyperfocal distance,
    Df=infinity, Dn=H/2

    The depth of field Df − Dn is DOF=2Hs2/(H2-s2), etc...

    Confused now? haha, just wiki DOF lah. If not go riceball to buy a few good books for your bedtime reading. Cheers
    Canon EF prime, macro & L lenses on EOS30D

  11. #11

    Default Re: Shallow DOF

    i actually don't know when to use what fstop with what focal length to achieve best results.

  12. #12
    Senior Member zac08's Avatar
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    Default Re: Shallow DOF

    Quote Originally Posted by boredphuck View Post
    i actually don't know when to use what fstop with what focal length to achieve best results.
    The largest aperture you can get away with to maintain DOF in your shots....
    Michael Lim
    My Flickr Site

  13. #13

    Default Re: Shallow DOF

    wheres riceball? at first i tot u ask me buy mua chee go home eat. haha.

  14. #14

    Default Re: Shallow DOF

    Quote Originally Posted by zac08 View Post
    Eh.... you have to be careful with such phrasing, else they may mistake using f11 or f16 as a smaller aperture value.

    A large aperture in correlation to the lens focal length will give you a nicer blur of the background as well as foreground. Often it will mean as big as f1.4 to f1.8 for a short focal length of 50mm. As the focal length increases, you can use smaller apertures such as f5.6 or f8 to the same effect.
    Aiyah.. you also not exactly right.. f-number is a reciprocal.. so the number is at the denominator. f/1.4 or f/11. f refers to the focal length. So the bigger the denominator, the smaller the aperture and vice versa. It's just Maths.
    Last edited by lsisaxon; 3rd September 2007 at 05:42 PM.

  15. #15
    Senior Member zac08's Avatar
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    Default Re: Shallow DOF

    Quote Originally Posted by lsisaxon View Post
    Aiyah.. you also not exactly right.. f-number is a reciprocal.. so the number is at the denominator. f/1.4 or f/11. f refers to the focal length. So the bigger the denominator, the smaller the aperture and vice versa. It's just Maths.
    I know... but I was hoping to reduce the confusion
    Michael Lim
    My Flickr Site

  16. #16

    Default Re: Shallow DOF

    ahh ... so the actual effect very much still depends on the focal length regardless of the other value?

  17. #17
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    Default Re: Shallow DOF

    it actually depend on both combination

    focal length
    18mm----300mm
    large------small DOF

    f/16------f/1.4
    large-----small DOF

    So a 300mm lens at f/1.4 () will give you very very narrow depth of field.
    a 18mm lens at f/16 will give you large depth of field, which mean most thing will be in focus.

    Still got another influence, depend on how close is the focus subject toward the lens, the closer the subject the shallower DOF.
    e.g.
    a subject shoot by 50mm lens f/5.6.
    further---------closer
    large---------small DOF

    you can use the DOF calculator at the link to simulate the situation you want.
    http://www.dofmaster.com/dofjs.html
    Sony Alpha 700 hobbyist

  18. #18

    Default Re: Shallow DOF

    tat whats wad i meant. a f/5 on 2 different focal length will give very different results. i'm using a pns. no wonder i have to stick my face into the object to get a good narrow dof.

  19. #19

    Default Re: Shallow DOF

    Quote Originally Posted by boredphuck View Post
    tat whats wad i meant. a f/5 on 2 different focal length will give very different results. i'm using a pns. no wonder i have to stick my face into the object to get a good narrow dof.
    Its 'shallow', not 'narrow' ... DOF as the name implies is 'depth' how far into a picture is an object in focus. Not how far away from the centre of a view that its in focus.

    Some picts of focusing off-centre and on-centre for comparison might make a better point.

    Generally P&S can take pretty good shallow DOF pictures but only at Macro level. once you get big objects, even with a f2.8 aperture, its quite hopeless unless its some very brightly conditions. I tried with my prosumer camera, never could get it to work well with objects bigger than a pail!

  20. #20
    Moderator ortega's Avatar
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    Default Re: Shallow DOF

    in order to get a shallower DOF on your lens

    • zoom to the longest focal lenght
    • use the biggest aperture you have
    • position subject further away from the BG
    • position subject closer to the camera

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