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  1. #1
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    Question regardin aperture/dof.

    Hi all,

    There's something that I don't really get:

    In all the photo books and sites that I've read, it always says that I want a smaller aperture (say f/22) when I want the whole scene (from in front of camera to infinity) in focus, and that if I want a blurred background, I should use a wider aperture (say f/4).

    Now, I sometimes look at random photos on flickr and try to guess the settings that the photographer has used, before checking the actual settings, it's quite a good exercise.
    However, I was looking at some photos of subjects far away (say Statue of Liberty from Battery Park) and despite the subject being quite far away, the photographer only used like f/5.6 or f/11.
    I just don't understand how/why these settings would work with such a far away subject, if you're supposed to use the smallest aperture for far away subjects.

    Can anyone clarify this?

    Thanks,
    Last edited by jai; 07-26-2008 at 10:27 AM.
    jai : amateur photographer

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  2. #2
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    Some of the answers may lie here > http://www.dofmaster.com/index.html

    Try the online calculator plugging in various values of distance and aperature to see what the resulting DOF is.

  3. #3
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    Depends on focal length as well as subject distance. Go to this link http://www.dofmaster.com/dofjs.html and play around with the values and see how it affects whats in focus.
    Last edited by D Thompson; 07-26-2008 at 11:31 AM. Reason: Mark beat me to it
    Dennis

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  4. #4
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    Quote Originally Posted by jai View Post
    ....you're supposed to use the smallest aperture for far away subjects.
    Who said you're supposed to use the smallest aperture for far away subjects? That's a generalization (or misunderstanding) that doesn't hold up at all. DOF is the zone of focus in front of and behind the SUBJECT. If I'm tightly focused on a distant subject and don't care about the foreground and background, all I need is enough DOF for the subject regardless of how far away I am. Haven't you seen countless wildlife shots that were taken at 500mm where the subject is sharp, but the background is blurred? Tightly focused, larger aperture. The rules don't go completely out the window because of distance (although the apparent DOF is less at longer focal lengths...and, I'm not going to get into the Circle of Confusion here...that's homework for you). Bottom line: Choice of aperture, regardless of focal length, all comes down to the photographer's intent (assuming, of course, that the photographer has a clue about what they're doing!).

    Now, that being said, any landscape photographer worth their salt will tell you, if you are including foreground and background elements in a landscape photo, you generally want all elements in focus and should use the hyperfocal distance, whatever it my be, for you aperture (typically smaller...but not too small otherwise you start having to deal with diffraction) and focal length combo. Typically an aperture of f/11 to f/22 (using the hyperfocal distance), depending on the lens and the scene, is sufficient in landscape photography if you want all elements in focus.
    Last edited by JTL; 07-26-2008 at 08:46 PM.
    Some Gear: Nikon D700; Nikkor AF-S 50 f/1.4 G; Nikkor AF-S 24-85 3.f/5-4.5 G ED; Tamron 28-300 f/3.5-6.3 VC; Nikon SB-800; Velbon Maxi-F; Canon Pixma Pro 9000; Canon S3IS, Canon SD500; Epson 4990; Epson P5000; Wacom Intuos 3

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  5. #5
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    Quote Originally Posted by JTL View Post
    Typically an aperture of f/11 to f/22 (using the hyperfocal distance), depending on the lens and the scene, is sufficient in landscape photography if you want all elements in focus.
    on landscapes i am often finding myself using f5.6 to f13 depending on light intensity. i rarely try out a greater f number than 13. am i stupid on this?

  6. #6
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    Quote Originally Posted by Gintaras View Post
    on landscapes i am often finding myself using f5.6 to f13 depending on light intensity. i rarely try out a greater f number than 13. am i stupid on this?
    No...you're not stupid. Stupid is a harsh word! It's depends on what you're going for. But, even with a crop sensor, f/5.6 can't possibly give you an adequate zone of focus and, subsequently, the sharpest image front to back if you're a shooting a deep landscape. With a crop camera f/11 to f/16 should be sufficient...I rarely go over f/16 on a crop camera; for film/full frame f/22...
    Last edited by JTL; 07-27-2008 at 08:55 AM.
    Some Gear: Nikon D700; Nikkor AF-S 50 f/1.4 G; Nikkor AF-S 24-85 3.f/5-4.5 G ED; Tamron 28-300 f/3.5-6.3 VC; Nikon SB-800; Velbon Maxi-F; Canon Pixma Pro 9000; Canon S3IS, Canon SD500; Epson 4990; Epson P5000; Wacom Intuos 3

    Main Software: Capture NX2; Adobe PhotoShop CS2; Corel Paintshop Pro X2 Ultimate

    Sold: Canon XT/350D, EF 24-105mm f/4 L IS, EF 100mm f/2.8 Macro; EF-S 10-22mm f/3.5-4.5, Sigma 18-200 OS; Canon ET EF 25II; Kenko Pro 300 DG, Canon 430EX, Canon BG-E3.

  7. #7
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    JTL is right, especially if you have foreground objects in your landscape (what he calls a deep landscape.) Meaning that parts of the picture are much closer to you than other parts. In order to get the foreground and the background in focus at the same time, you need a small aperture, such as f/16. But if everything in the picture is far away from you (like you're shooting the mountains across the lake) then the aperture isn't as important. The whole picture is at infinity focus (or close to it) so it might look fine at f/5.6. I usually don't go any bigger than f/8 for landscapes, though.
    Nikon D50, Nikkor 18-55mm, Nikkor 50mm 1.8, Sigma 70-300mm APO DG Macro, Tokina 12-24
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  8. #8
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    Smile

    Wow, thanks.

    So let me get this straight, changing your aperture settings in order to set your dof is actually setting the area of focus in front and behind a desired subject?!?
    I always thought that it was the amount of focused area from in front of the camera to the subject!

    So that's why lenses with wider maximum apertures are more expensive: because they can have a much shorter area of focus in front and behind a subject!

    So basically, what I should do is:
    - Focus on a subject (either in manual focus or automatic focus).
    - Then set the aperture depending on how much I want in focus in front and behind the subject.
    - Set the ISO/ shutter speed.
    - Snap away!

    So, in fact, I can have a wide aperture for even a far-away subject!

    You learn every day!
    jai : amateur photographer

    Camera:
    Canon EOS 400D (XTi) Body - Black

    Lenses:
    Canon EF 50mm 1.4 USM
    Canon EF-S 18-55 IS (on order)

    Accessories:
    Canon ES-71 II hood
    Canon EW-60C hood (on order)
    SanDisk CF 2GB Extreme IV
    SanDisk CF Cardreader Extreme (Firewire)
    Lowepro Slingshot 200AW
    Slik Mini Pro III Tripod
    Manfrotto 055ProB Tripod with Manfrotto 488RC2 Head.
    Canon RC-1 Remote

  9. #9
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    Quote Originally Posted by jai View Post
    Wow, thanks.

    So let me get this straight, changing your aperture settings in order to set your dof is actually setting the area of focus in front and behind a desired subject?!?
    I always thought that it was the amount of focused area from in front of the camera to the subject!

    So that's why lenses with wider maximum apertures are more expensive: because they can have a much shorter area of focus in front and behind a subject!

    So basically, what I should do is:
    - Focus on a subject (either in manual focus or automatic focus).
    - Then set the aperture depending on how much I want in focus in front and behind the subject.
    - Set the ISO/ shutter speed.
    - Snap away!

    So, in fact, I can have a wide aperture for even a far-away subject!

    You learn every day!
    You got it. But...most photograhers work the other way around...they decide the zone of focus/depth of field they want and what aperture they should use to achieve it, set the aperture...then focus and shoot. Also, when using a telephoto zoom lens, all you need to do is keep a little mental note in your head to be aware of the focal length you're shooting at as well...
    Last edited by JTL; 07-28-2008 at 04:03 PM.
    Some Gear: Nikon D700; Nikkor AF-S 50 f/1.4 G; Nikkor AF-S 24-85 3.f/5-4.5 G ED; Tamron 28-300 f/3.5-6.3 VC; Nikon SB-800; Velbon Maxi-F; Canon Pixma Pro 9000; Canon S3IS, Canon SD500; Epson 4990; Epson P5000; Wacom Intuos 3

    Main Software: Capture NX2; Adobe PhotoShop CS2; Corel Paintshop Pro X2 Ultimate

    Sold: Canon XT/350D, EF 24-105mm f/4 L IS, EF 100mm f/2.8 Macro; EF-S 10-22mm f/3.5-4.5, Sigma 18-200 OS; Canon ET EF 25II; Kenko Pro 300 DG, Canon 430EX, Canon BG-E3.

  10. #10
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    jai,

    This link goes into "hyperfocal distance" which is basically what you're attempting to do. If your subject was at "infinity" you could focus to a nearer point and achieve reasonable focus of close objects as well as the subject at infinity.
    Math test on page 2 of the link.

    http://www.vividlight.com/articles/3513.htm

    Older prime lenses actually had markings on them to indicate hyperfocal distance. In the image below, the inner scale 16< 2 >16 represents fstop scale of the aperature. Notice that the pointer shows the lens is focused at 5m. If the lens were set to f/8 by the outer aperature ring, the image should be in focus from about 2.5m to Infinity according to the hyperfocal scale, even though focused for a shorter distance.
    Attached Images Attached Images  

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