FLANGE DEPTH QUESTION

5 replies to this topic

#1 Daniel Porto

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Posted 18 March 2009 - 04:13 AM

Hey Everyone,

If the flange is out on the camera will the lens still be able to focus but at a different distance to what it the real distance actually is (depending on the distance) i.e. instead of being in focus at 2' on the lens it will be in focus at about 2'1" (the subject is 2' away)

Hope I explained myself clearly!
THANKS
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#2 timHealy

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Posted 18 March 2009 - 09:15 AM

Hey Everyone,

If the flange is out on the camera will the lens still be able to focus but at a different distance to what it the real distance actually is (depending on the distance) i.e. instead of being in focus at 2' on the lens it will be in focus at about 2'1" (the subject is 2' away)

Hope I explained myself clearly!
THANKS

1 inch doesn't sound like much, but do you have another lens to compare? The lens or the flange focal distance could be the problem.

best

Tim
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#3 Ryan Thomas

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Posted 18 March 2009 - 10:20 AM

Yeah, it will just focus at different distances. Depending on which direction it is though, you might not be able to hit infinite.
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#4 Allen Achterberg

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Posted 18 March 2009 - 12:31 PM

You will see big problems when wide open, and with wider lenses. It's very critical for your FFD to be correct if you plan to use wide lenses. When there is a problem, a wide lens will tell all! Also, check it edge to edge. Hopefully it would be squared. Otherwise you may get a slant focus problem with wider lenses.
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#5 Daniel Porto

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Posted 18 March 2009 - 09:19 PM

1 inch doesn't sound like much, but do you have another lens to compare? The lens or the flange focal distance could be the problem.

best

Tim

I wasn't referring to a particular lens just what would happen if the flange was out.

Thanks for all your help guys!
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#6 Satsuki Murashige

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Posted 19 March 2009 - 01:35 AM

I've noticed that usually if the flange is off, the focus is short. 5' on the lens is really 4'6", etc. You won't be able to focus to infinity and a wide lens will always looks slightly soft. This is a good thing to watch out for on shoots with HD lenses that have backfocus rings (or with the Red or 35mm adapter setup), periodically check the big monitor for soft looking wide shots. Longer lenses can still be focused sharp thru the viewfinder/monitor but the marks will not match up. So in a pinch you can get eye marks or pull wirelessly from a monitor with HD. Just so we're clear, I'm not recommending this but if it makes the difference between getting a shot or not getting it, then you might have to do this.
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