Originally Posted by dave61
Interesting--trouble focusing if the M-3 VF adapter is removed? The RF linkage on Leicas is internal + mechanical. The viewfinder and bright-lines are optical. The focus is a relation between the RF cam within the camera and the RF coupling within the lens. The 35mm VF adapter for M-3's doesn't affect the focusing mechanism the way it does on a 50mm DR Summicron.
If the lens is focusing properly with one camera, it should do so on another-with or without the optical VF adapter. I have an M-3 and a CL. I use one mid-sixties E.Leitz Canada (chrome) 35mm f/2.0 Summicron on both.
I removed M-3 adapter ("eyes") to use lens on my CL. I use auxilliary 35mm VF clipped in the shoe. The results: Focus is spot-on with or without adapter on M-3. I verified focus with GG on film plane w/ 8X Agfa loupe.
Results on CL indicate no issue with accuracy of rangefinder-50mm frame pops up, which I ignore, and I don't think CL has any paralax correction. I use auxilliary VF anyway.
Accuracy of focus is fine, although distance scales reads out differently on the two cameras. CL indicates in focus at 15 feet, M-3 indicates in focus for same point is 10 feet. However, checked on GG at film plane, when RF indicates it's sharp, it is.
Perhaps there's a calibration issue in the RF mechanism? I'm also pretty sure the magnification of the M-4 VF is different then the M-3 VF, so angle of view will be off with the M-3 adapter used on M-4.
When the eyes are removed from the lens, it will focus right, but only at infinity. The closer you focus, the more the focus will be off.
That's the reason Leitz made two different models, with or without eyes. With the exeption of the Summaron 35mm f/3.5 (with eyes) it is not easy to remove the eyes. In manuals is always stated that the eyes must stay in place.
You must not forget that the rangefinder is optical, not only mechnical. The optics of the eyes do change the optical effect of the rangefinder, wich is corrected by the focusing helix of the lens. That's the reason focusing will be off without the eyes.