Back Focus Revised - New Info...

Started Dec 29, 2005 | Discussions thread
Rinus Borgsteede Veteran Member • Posts: 3,207
Change the order

Cam 1 depends on the position of Cam 2. Change Cam 2 and you need to redo Cam 1. Seems to me that your order demands that Cam1 always needs rechecking last.

I believe that starting with Cam 2 is the only way to go but I also think that Cam 1 may be the only one that needs to be adjusted )1 if manual focussing is a problem for the user )2 keystoning is introduced. A new test could be added for linearity of the VF mirror, as the adjusted position may cause keystoning or maybe it already exists. If keystoning exists in the ccurrent or adjusted setup, the upper and lower area of the screen can no longer be used for either manual or automatic focussing as the plane of focus runs away from the center point up and down.

The adjsutment of Cam 2 should really adjust for keystoning, not focus.If the manual focus is then wrong, it can only be solved by repositioning of the CCD. Only correct positioning of Cam 2 and thus the Vf mirror will allow for the best adjustment for Cam 1 the Af mirror.

I hope you see that adjusting Cam 2 is a two sided sword. It could cause a lot more problems.

Ultimately I suggest to only adjust the Autofocus AF Cam 1 as testing for keystoning is another more difficult test that also requires a lens without distortions.

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Rinus of Calgary/Kelowna

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