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Greg Lytle

Focusing question from amateur with split viewfinder

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Hi folks,



I own a Porst 650 XL and Porst 1500 XL Microcomputer and was wondering about the the precision of the split viewfinders on each of them. I read the instructions which instruct me to zoom in all the was, focus zoomed in, the zoom out to a desired wider angle. When I zoom in to focus, the split finder lines up, but the split finder lines do not stay aligned upon zooming out and I guess I thought the lens should be parafocal upon zooming. Does this mean my split viewfinder is not accurate? Any guidance is appreciated.



Thanks,


Greg Lytle


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Split-image rangefinders can be prone to error caused by the accommodation of the eye if there's no ground glass, but it's possible the lens is out of adjustment. Try a tape measure test to see if your focusing matches up with the lens scale. I would tend to trust the zoomed-in setting.

Edited by Mark Dunn

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Thanks Mark, I did just what you suggested, I think. I put the 1500 on a tripod and put a flat focus target 8 feet from the film plane. I then set the focus of the lens to 8 feet. It seemed dead-on. The focus ring does not move at all when zooming out, and it appears the rest of the field of view stays in focus, so I think that worked. I will do the same test on the 650 tonight. I appreciate your help!

 

Greg Lytle

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