Replacing a front cell focus folder focus scale that is missing?

jeffreythree · Jul 27, 2015

I have a little project camera that I am tinkering with, specifically a Semi Minolta II 6x4.5 format with a f3.5 75mm lens. The main issue is the front cell focus lens is missing the focus scale. Am I wrong in thinking I can use a piece of ground glass on the film plane to focus on marked known distances and mark them on a replacement ring? I might even just try to focus to the hyperfocal distance and leave it as a fixed focus.

AgX · Jul 27, 2015

You are thinking right.

ic-racer · Jul 27, 2015

I can always guess better than hyperfocal focusing.

jeffreythree · Jul 27, 2015

ic-racer said:
I can always guess better than hyperfocal focusing.

I was just thinking I would just need to measure off and focus to one distance that way, and then a dab of adhesive to keep the lens from rotating. Right now it would truly be guess work with no idea at all where it is focused to.

nosmok · Jul 29, 2015

You could also just put Scotch "magic tape" across the film gate and get the focus distances that way. Easier than mucking with glass.

Trask · Jul 30, 2015

I once did this with a Frankenpolaroid -- put tracing paper in a polaroid holder in the film plane and insert into camera, put camera on tripod, open shutter on "B" (I'd replaced the original lens). At some distance, put a bright point source light -- I used a small single-filament bulb flashlight, these days you could use a bright single LED light. Measure the distance from the film plane to the light, focus on the tracing paper (easiest if all other lights are off), then mark your scale. In my case, I also had to check infinity in daylight on a distant object because by swapping the lens it was possible the camera would focus past infinity.

flavio81 · Jul 30, 2015

jeffreythree said:
I have a little project camera that I am tinkering with, specifically a Semi Minolta II 6x4.5 format with a f3.5 75mm lens. The main issue is the front cell focus lens is missing the focus scale. Am I wrong in thinking I can use a piece of ground glass on the film plane to focus on marked known distances and mark them on a replacement ring? I might even just try to focus to the hyperfocal distance and leave it as a fixed focus.

Yes, you are correct.

My suggestion is: Do exactly that, but for infinity, do not calibrate for "sharpest center when wide-open" at infinity. Calibrate for overall best image quality at all the field (that is, centers, edge and corners) at about f5.6 or f8 aperture.

Replacing a front cell focus folder focus scale that is missing?

jeffreythree

AgX

ic-racer

jeffreythree

nosmok

Trask

flavio81

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