Finally bought an HD Lens, but I have a small technical question about it...

Mike Krumlauf

Mike Krumlauf

Award Winning Filmmaker
So I got a Fujinon HD Zoom that has auto backfocusing built into it and for some reason it doesnt want to back focus to the F23's plane correctly. I can use the lens fine, i just have to change focus when i change my focal length on the zoom, the focus does not lock full zoom range,so no zoom motions during recording unless im stopped down to f5.6 or so... any idea why this might be? Its meant for 2/3" sensors... is it an F23 problem? Wish i still had my varicam or F900 to test this.

The lens model is the XA16x8A Fujinon HD Zoom.
 
Wasn't this an OEM lens for the Sony PMW-350? It probably only works fully(properly) with that camera, or others designed for it.
 
Heres a funny thing, there was already a lens file for this lens in my camera in the lens file menu. #33. It works fine, just cant hold the focus so you just need to adjust focusing when you zoom. Ive heard of people shimming their system to fix this problem?
 
You're supposed to be able to adjust the flange distance using an Allen wrench and a screw driver on the front panel. The screw should be right above the lens mount. The problem is that will change everything for all your other lenses. Check if you never had perfect infinity focus on your other lenses. It that's the case, then you need to change the flange distance in the camera. If not, then your new lens needs to be shimmed somehow.
 
It was the easiest thing in the world. there was a little button on the bottom grip "f.f". you hold it for 3 sec, the lens zooms in, you focus it, press the button it zooms out you focus again, done backfocus set... so happy and excited! :D
 
This lens is unbelievably sharp and beautiful as Fujinon usually is! What a difference compared to the POS Canon SD lens I was using! Will post some footage soon.
 
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