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Switching depths of field


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#1 Nick Cooke

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Posted 18 May 2007 - 03:18 PM

I've recently ventured onto using film, as opposed to DV, and have realised that my basic understanding of the way the Digital camera works, doesn't help me when shooting on film. So I wondered if you could help me clear this up... I think I'm close, just getting digital techniques and stills film mixed.

For example if your shooting a close up of a face with a small depth of field example 2.6, seperating the face from the background, then you switch to a wide shot of 22. How do you get the two to match with out the exposure being completely different but still keeping the depth of field the same?

I believe the answer is in an ND?

As you can see I'm a little lost, thanks, Nick
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#2 Michael Collier

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Posted 18 May 2007 - 03:54 PM

Yup. ND. you just answered your own question. Or use a different shutter, if your going for that look too. But its no different than video. Video same as film you place ND the same to control DOF. You have your filter wheel, at least one of those is an 85b with an ND on it (or in smaller cameras, they might have an ND selector switch on the body or lens) and you can always turn on your shutter on video to take advantage of lower DOF, though you get the look imparted by having such a short shutter, so ND unless short shutter is something you want.
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#3 Michael Nash

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Posted 18 May 2007 - 05:16 PM

For example if your shooting a close up of a face with a small depth of field example 2.6, seperating the face from the background, then you switch to a wide shot of 22. How do you get the two to match with out the exposure being completely different but still keeping the depth of field the same?


By "2.6" and "22," are you referring to f-stops, or the measure of the depth of field?

In any case, you typically control depth of field between different shots by maintaining a consistent f-stop. It usually appears most natural to see a little more depth of field on the wider shots, and then lose a little as you go in tighter. You usually wouldn't want your wide shots to have the same shallow depth of field as a closeup! (nor would it be physically possible, in most cases).

If you keep your distance-to-subject and f-stop close to the same between setups, the difference in focal lengths will take care of the depth of field for you. If you need to "fudge" it for a certain shot, you can change your aperture (using ND filters, if necessary), or your distance & focal length.
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#4 Nick Cooke

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Posted 18 May 2007 - 07:23 PM

Thats a great help thanks, i'm going to get out and try a few test shots, really cleared things up for me.

Nick
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