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Old February 11th, 2011, 09:12 AM   #1
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DOF ranges

First up let me say I am a long time stills photographer but using video as well now. What I am interested to know is what the range of in focus parts of a shot are at a given aperture/iris setting.
I know them for my DSLR. ie at f2.8 I have a very small part of the image in focus and at f11 a large area etc. I know how to work them out.

How does this work with 1/3'' video cameras lenses and iris settings? I own a Canon XF300 and would find this info of great value. I shoot a lot of aviation subjects and getting a large DOF is important while also maintaining a high enough shutter speed. Last time I filmed in lowish light the camera stopped down to f2.8 I think and I had no real idea of how much of the scene would be in focus.

Andy S
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Old February 11th, 2011, 09:23 AM   #2
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Online Depth of Field Calculator

HTH

Cheers,
GB
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Old February 11th, 2011, 09:27 AM   #3
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Cheers Geoff. I have sued that site before but never realised it did video as well as stills cameras!
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Old February 11th, 2011, 12:01 PM   #4
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. I have sued that site before
Why are you so litigious? ;-)
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Old February 11th, 2011, 01:53 PM   #5
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Why are you so litigious? ;-)
Haha that's a bad typo!
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Old February 13th, 2011, 10:47 AM   #6
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If you're from still photography you know that DOF increases the shorter the focal length, just as it increases with f-stop. DOF is a the combined optical property of aperture and focal length.

Now, it's the actual focal length, not the 35mm equivalent, that determines the DOF. The 1/3" has a crop factor of 7.2. In 35mm photography you'll have a nice shallow DOF suitable for portraits when shooting with a 85mm, not so with the 1/3" sensor, as the actual focal length of the 85mm equivalent is 12mm.

Using a strong zoom you can reduce the DOF, but this also has the effect of flattening the image.

BR, Erik
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Old February 13th, 2011, 10:59 AM   #7
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I'm actually for the most part wanting big DOF not small. I film a lot of aviation, ie planes taking off and landing, and need it all to be in focus. When taking stills of planes I would avoid anything less than about f4 but mainly use f8-11. With the XF300 these settings are completely different I think and you get much more DOF at lower f numbers. It's just a case of learning which give the required DOF I guess.
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Old February 13th, 2011, 11:29 AM   #8
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Hooray for somebody else for whom DOF actually means "Depth Of Field" and not "the smallest possible area in focus." :-)
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Old February 13th, 2011, 11:34 AM   #9
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It can be used to good and bad effect. I don't think seeing a plane with the body in focus but the wings all blurred would work!
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Old February 13th, 2011, 12:06 PM   #10
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I hope that as the newness wears off, tasteful depth of field usage will become more the word of the day. I have seen enough rack focus shifts from one nostril to the other. I have yet to see anything 'artistic' about it either. The word 'Cinematic' is often used to describe this stuff but I believe it's an abuse of the word. You don't see extremely shallow depth of field used in Hollywood productions for example. Rarely is there a need to obliterate location awareness either. It often looks great to have a soft background because it helps direct attention to the subject. Now, that's Cinematic. But the relentless battering of the senses with extremely shallow depth of field on every shot punctuated with nausea inducing rack focuses looks very amateurish. The best comparison that I can make is the 'wowie-zowie' zooms that were done in the early days of VHS video cameras. When you look at that stuff now, you just laugh. But when that swill was produced, the shooter thought is was really great stuff. In a few years the abusive overuse of extremely shallow depth of field will get the same amused laugh. There is a huge difference between artistic shooting done in good taste and a gimmick.
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Old February 13th, 2011, 12:24 PM   #11
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Jim,
That is the best summing up of this current madness that I've read anywhere - thank you!
(The fact that it's now prevalent in cooking programmes is an indictment in itself...)
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Old February 13th, 2011, 12:35 PM   #12
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Yeah I fully agree Jim.

It can be used to highlight things if not done too much. For example when filming in aircraft cockpits it can be used to direct attention to say the throttles as long as the rest of the background is still recognisable. It can only be used a few times without it looking silly and boring.


Robin - It's used a lot in gardening programs as well!
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