range finder frame line switching not working

[chester6]

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Currently my rangefinder is on 50/75 frame line, when I switch in the back it temporarily goes to the 28/90 when the switch is held, but then flips back to 50/75 when I let go. My current lens is a voigtlander 40mm, and I would like to switch to 35mm frame lines, but can't seem to get there. I have my "Lens Detection" setting set to manual M 35mm F1.4

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[adan]

1) Lens detection has nothing to do with choosing the framelines - they are fully mechanical (as designed in 1954).

2) Your 40mm lens is setting the lines to 50, through a mechanical tab on the rear of the lens pressing a lever inside the camera's lens mount.

3) You can overide the lens mechanical connection by pressing the selection lever - but only temporarily against spring pressure. The lens tab connection will always force it back to the 50mm setting chosen by Voigtlander for this lens (for which there are no 40mm lines in the M cameras) when you let go of the lever.

So what you describe is normal.

4) The only way to fix this more permanently requires filing down the metal tab on the lens a mm or so - in which case it will always show the 35mm lines, unless someone welds some more metal back on to restore it to original condition.

Edited October 30, 2023 by adan

[adan]

This give a "picture" of what is happening. Inside the camera's lens mount is a connecting rod (red) to the viewfinder. Putting on a lens moves that rod a specific amount, depending on the length of the mounting flange that is in that area when the lens is mounted. Which is chosen by the lens maker.

And that brings up a specific frameline or set of framelines - 90/28, 50/75 or 35/135 and holds that in place.

The external lever can overide that connection temporarily with finger pressure - but it will spring back to what the lens is commanding, brass on steel, when you let go.

A long flange will show the 28-90 framelines, a medium flange length will push less, amd show the 50-75 lines, and a very short flange (or no lens mounted at all) will allow the 35-135 lines to show. So the "50mm/75" flange Voigtlander built into your 40mm, must be shortened to the "35/135" length to show the 35 frames full-time.

Of note, to temporarily see the 35mm lines with yout lens - push the lever AWAY from the lens mount as far as it will go.

 

Edited October 30, 2023 by adan

[chester6]

thanks for the explanation! I didn't realize it was a physical mechanism, I don't need to change it, just thought it might have been a bug with the camera. Guess it would've been more obvious if I had more than 1 lens for the camera

Edited October 30, 2023 by chester6

[dpitt]

The 35 mm frame lines work perfectly for my Summicron 40C (I had mine modiied to bring the 35mm frame up iso the 50 mm). All I have to do is frame inside the framelines, so not use the thickness of the frame line and a bit outside as I can do with a real 35mm lens.

Most of the time I forget that it is not a real 35mm and shoot away...

The 50 mm lines are useless for me with the 40Cron.

Edited October 30, 2023 by dpitt

[Siriusone59]

Just a suggestion, you could compare the live view screen with what you see thru the finder and how much the live view shows beyond the 50mm frame lines.  It might not make that much difference depending on how critical your needs.  I do that when using a 24mm and don't feel like mounting a visoflex.