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-   -   Fujinon Feedback/Back focus. (https://www.dvinfo.net/forum/sony-eng-efp-shoulder-mounts/82054-fujinon-feedback-back-focus.html)

Michael Knight December 19th, 2006 01:03 AM

Fujinon Feedback/Back focus.
 
Just a quick note.

Got our lens back from Fujinon today.

They found no problems with the lens...nor was it a pre-production model ....so it must have been OE (that's an acronym for Operator Error) which more than likely was in the back focus adjustment being done with too small of a chart.

Nevertheless, if anyone can run me through the "professionals" back-focus process I'd appreciate it. We did this using a monitor today, and it seems okay now.

However, absent a chart, we simply zoomed in on a vertical straight edge 16ft away, then pulled wide and adjusted the back focus.

But are there other things one should do to ensure the lens is good at all focal lengths/stops?





Michael Knight.

Greg Boston December 19th, 2006 09:12 AM

Quote:

Originally Posted by Michael Knight
However, absent a chart, we simply zoomed in on a vertical straight edge 16ft away, then pulled wide and adjusted the back focus.

The usual recommended distance is 3 meters. So, roughly 11 feet. A good sized Siemen's chart will make the task much easier.

-gb-

Bob Willis December 19th, 2006 01:05 PM

Use the ND filter wheel to make sure you are nearly wide open on the lens. That gives you a shallow depth of field to more acurately focus the back flange distance.

Michael Knight December 19th, 2006 10:02 PM

Much appreciated.

Siemens chart is on the way.

Then watch me spin some wheels.

Michael Knight.


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