Is there a Voigtländer expert in the room? - The lens affaire.

[Larrea]

Hi...
I have two Voigtländer VITO C.
Hopefully, with these two I will build a good one.
The problem is that the camera that is in the best conditions (the receiver) has a LANTHAR 2.8/50 lens and "the donor" comes with a COLOR-LANTHAR 2.8/50, I understand better quality.

The receiver and the donor

The receiver's optical train rings are in much better condition and outwardly looks identical in measurements to those of the donor.
Both shutters require cleaning because they move slowly and in the case of the donor, it remains slightly open. It is clear that I will have to disassemble to clean and lubricate.
Will it be possible to place the COLOR-LANTHAR glasses on the LANTHAR body as a simple replacement?
Regards
Eduardo Larrea

 

[shutterfinger]

Will it be possible to place the COLOR-LANTHAR glasses on the LANTHAR body as a simple replacement?

As a physical swap YES, optical swap NO. Lens are rarely their marked focal length due to production tolerances. The difference in focal lengths can be as little as .1mm or as much as 3 mm either side of the nominal value.
Make a ground glass to fit on the film rails at the image plane so that it sits in the camera like film will. The ground glass can be a clear piece of glass or acrylic with strips of transparent tape next to each other then place the gg with the tape side facing the lens. Place both cameras at the same position and focus each on a target with fine detail. If both lens are the same focal length both will indicate the same focused distance. You can also measure from the film plane to the target then check each camera's focus scale for the indicated distance when the target is in sharp focus at the film plane.
Set each lens at f2.8 and open the shutter on B.

 

[albada]

I suspect that the lenses are identical, and that "COLOR" was added to the name to say the camera is suitable for color film. But as shutterfinger warned, focal lengths vary within a tolerance, so you should check focus-accuracy with the method he describes above. My approach is to lose calibration of focus upon disassembly, and re-calibrate upon reassembly using shutterfinger's method: Adjust until sharp at infinity, and then tighten the set-screws around the focus-ring.

Mark Overton

 

[macfred]

I suspect that the lenses are identical

I guess you're right - both Lanthar lenses were simple consumer grade triplets (which does not mean that they are bad lenses).

 

[Larrea]

Thank you. I'll try it.