Reverse Zone Focussing

[Steve Ricoh]

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Read this if like me you faff around twiddling focus to get perfectly aligned focussing patch on a RF.

https://www.leicalensesfornormalpeople.com/2021/10/20/reverse-zone-focusing-or-learning-to-be-faster-with-your-rangefinder-camera/

[Alberti]

Once I patched some yellow filter on the RF glass of my M8. So I could see which image was which when checking the allowed difference. This link does not clearly show me how it is done. 😪

The old M2 had a beautiful rangefinder patch with a small and a large pad, the small one on top and the larger on the bottom, that showed the allowed delta between the two patches - and hence the depth or change of focus. I imagine it helped combat focus shift in those old days . . 

Edited January 12, 2022 by Alberti

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[jaapv]

Quote

Someone smarter than I will/can/should come up with a better name for what I am describing. If that is you, please contact me. I will update this post. I am not attached to the term “reverse zone focusing.” I almost hope it doesn’t stick. It sounds stupid. 

Farting around? Sheesh... 🙄

[Steve Ricoh]

22 hours ago, Alberti said:

Once I patched some yellow filter on the RF glass of my M8. So I could see which image was which when checking the allowed difference. This link does not clearly show me how it is done. 😪

The old M2 had a beautiful rangefinder patch with a small and a large pad, the small one on top and the larger on the bottom, that showed the allowed delta between the two patches - and hence the depth or change of focus. I imagine it helped combat focus shift in those old days . . 

The author was experimenting to find the latitude of alignment.

For several years I’ve been hunting back and forth to get precise alignment of the ghost image, as near as humanly possible. I’ve been wasting my time, it would appear, near enough will do (depending on focal length and aperture of course).

[jaapv]

It is absolute nonsense One would have to determine the delta for each aperture, each subject distance and each print size. And each subject's frequency and contrast, for that matter.

[Steve Ricoh]

I’m more interested in the principle, not the absolutes.

 

[jaapv]

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The principle is OK, for the absolute, which this guy strives to find, see my post above...