Focal Plane Mark

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Jim DeLuca

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Focal Plane Mark

PostFri Jun 28, 2013 8:10 pm

I did a search of the forums and I can't seem to find a definitive answer. Does anyone know exactly where the focal plane is? There isn't a focal plane mark that I can find on the BMCC MFT.

I'm doing this to really check the distances on my slr magic lens, want to make sure the marks are good, while I'm also testing if it's focusing to infinity properly.
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Frank Glencairn

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Re: Focal Plane Mark

PostFri Jun 28, 2013 9:29 pm

The viewfactor cage has a plane mark on it.
It's about a third between the front edge of the camera and the treaded holes.
https://sites.google.com/view/frankglencairn/home
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Jim DeLuca

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Re: Focal Plane Mark

PostFri Jun 28, 2013 10:13 pm

Frank Glencairn wrote:The viewfactor cage has a plane mark on it.
It's about a third between the front edge of the camera and the treaded holes.


That seems to be inline from what I'm testing. Frank do you have the slr magic lenses? How do you find the accuracy of the witness marks on the MFT version?
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John Brawley

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Re: Focal Plane Mark

PostFri Jun 28, 2013 11:01 pm

Jim DeLuca wrote:I did a search of the forums and I can't seem to find a definitive answer. Does anyone know exactly where the focal plane is? There isn't a focal plane mark that I can find on the BMCC MFT.

I'm doing this to really check the distances on my slr magic lens, want to make sure the marks are good, while I'm also testing if it's focusing to infinity properly.


It's something I've been asking to be put on the camera from the beginning !

I've always used the leading edge of the metal of the body itself (not the rubber). You can usually hold the tape hook to this edge but it's far far from ideal.

The SLR magic lenses witness marks aren't really good enough to be super precise. There's no actual lines for the distances, just the numbers themselves, like on most "stills" lenses.

jb
John Brawley ACS
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