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Thread: DOF(Depth of Field)

  1. #1

    Question DOF(Depth of Field)

    Hi guys,
    i have a problem, hope you guys can help me out.
    i want to take a group of 3-8 people in a line and i want them all clear.
    Increasing the f-stop just makes the background clear as well as the foreground.
    However, i do not know if it applies to focus. I can only focus on the middle, meaning middle will be sharp but the sides i must rely on the DOF to make it clear.
    I have tried using f11(my max aperture on the s602) and it appears to be BLURER then f/4.5. Wierd. Maybe my shutter speed was too low? i used 160.
    Sounds confusing. Hope you guys can tell me.
    Thanks for your time!

  2. #2

    Default

    3-8 people in a line perpendicular or parallel to your line of vision?

    If you notice that increasing the DOF makes the background and foreground clearer, you're doing the right thing.

    At f11, the likely culprit if your picture is blur, is camera shake. To reduce or eliminate this, use a tripod. You should end up with a sharp picture with large DOF.

  3. #3

    Default

    Hi streetshooter,
    Thanks for your reply.
    I mean people standing parallel to me, group shot.
    The wierd thing is that is DOF foreground and background.
    But the people are all standing in the same depth.
    so f11 should give a clearer picture, is a higher f-stop more sensitive to handshake? meaning like as the f-stop increases, it is more sensitive to movements as like increasing the zoom?
    Thanks for your time dude!

  4. #4

    Default

    Originally posted by mok
    Hi streetshooter,
    Thanks for your reply.
    I mean people standing parallel to me, group shot.
    The wierd thing is that is DOF foreground and background.
    But the people are all standing in the same depth.
    so f11 should give a clearer picture, is a higher f-stop more sensitive to handshake? meaning like as the f-stop increases, it is more sensitive to movements as like increasing the zoom?
    Thanks for your time dude!
    High F-stop means smaller aperture. And smaller aperture means you need a slower shutter speed to allow more lights to strike the CCD through the small aperture. Increasing the zoom/focal length will need steadier hands because of the (1/focal length) shutter speed rule.

  5. #5

    Default

    yeap, i'm wondering the same thing too......

    taking a photo of a grp of pple.. standing in 1 line.....

    should i use a small or large aperture? its same depth.. so can i use a smaller dof so that the background is blur and the grp remains clear, those at the side as well?

  6. #6
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    Default

    taking a photo of a grp of pple.. standing in 1 line.....
    should i use a small or large aperture? its same depth.. so can i use a smaller dof so that the background is blur and the grp remains clear, those at the side as well?
    Yes, as long as the depth of field is sufficient. Sometimes, e.g. for 2 rows of people, too large an aperture may cause one row to be blur.

    DOF is both in front and behind the focus point. Sometimes DOF is greater behind than in front. Depends on focal length, among other things.

  7. #7

    Default

    hmm okies. so if 1 line...... get a smaller dof... but if a few rows... bigger dof. okies. understand now.

  8. #8
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    one common trick is to use high ISO films... e.g. ISO 400 for day shoots or Press 800 for indoor shoots. that way, can use a very small aperture for maximum DOF and a acceptable shutter speed.

    try NPH400 or Press 800. the colours are very punchy for people shots.

  9. #9

    Talking

    Originally posted by blizzy
    hmm okies. so if 1 line...... get a smaller dof... but if a few rows... bigger dof. okies. understand now.
    errrhhh .....

    but me can alzo uze a large DOF for 1 row of pple ..... correct or not ..... ?? .....


  10. #10
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    Default

    Ya of cos. Larry's advice will also apply.

  11. #11

    Talking

    Originally posted by d7t3
    Ya of cos. Larry's advice will also apply.
    thankz .....


  12. #12

    Default

    Originally posted by Larry
    one common trick is to use high ISO films... e.g. ISO 400 for day shoots or Press 800 for indoor shoots. that way, can use a very small aperture for maximum DOF and a acceptable shutter speed.

    try NPH400 or Press 800. the colours are very punchy for people shots.
    yeah. i tried using nph 400. came out a lot nicer than normal film... will definitely use such potrait film for grp photos

  13. #13
    Silhouette
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    Default NPH 400

    Hi Blizzy can i ask u where u got ur NPH 400 film. I tried cathay and ruby, they never sell.

    Ethan
    regards

  14. #14

    Default

    i bought mine from colourlab at adelphi.. but i'm sure cathay photo at peninsular plaza sells it. i asked other day.

  15. #15

    Default DOP

    Actually, for DOF there are 2 parts to it.

    1st part is where aperture plays a part. Small aperture - large DOF, large aperture - small DOF.

    The other part is handled by the focal distance. The rule is such that at whatever focal distance you use, say 1m, then every thing 0.5x of the FD, and 2x of the FD will be in focus.
    So if you focus at something at 1m, you will get everything between 0.5m to 3m more or less focus, everything else will be out.

  16. #16
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    Default

    Actually, for DOF there are 2 parts to it.

    1st part is where aperture plays a part. Small aperture - large DOF, large aperture - small DOF.

    The other part is handled by the focal distance. The rule is such that at whatever focal distance you use, say 1m, then every thing 0.5x of the FD, and 2x of the FD will be in focus.
    So if you focus at something at 1m, you will get everything between 0.5m to 3m more or less focus, everything else will be out.
    1. Is this a sure thing? What aperture does this apply to? For different apertures, surely the range must change?

    2. There is a 3rd part: wider lens (e.g. 28mm), more DOF. Tele lens (e.g. 135mm), less DOF -- at same aperture.

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