Joe Mondello said:
Why didn't you just return them to where you bought them?
But I have to say that your experience seems very unusual given the other replies here.
Until this afternoon, returning the ones that don't focus correctly would have left me with only a 21mm- and though a fine lens, at f/4 it's kinda dark, and so wide, hard to cover with flash, making it difficult to cover interiors in a 'snapshot' sort of way. I don't like to think I bought an M8 and can't find good lenses for it.
I agree that these problems sound unusual. I can't explain it except in terms of "luck". Today I bought a 30-something year old Summicron-C to help make the returns easier, and it focuses perfectly.
I'd like to think of it as simple poor luck, and the vendor agreed that the lens I sent back (Nokton, so far) had a back-focus problem, and I'm sure the others will receive the same diagnosis. They are simply adjusted incorrectly. The 28mm Nokton too far (past infinity at infinity focus) and the 75mm too close (won't quite reach infinity- even on the rangefinder that's proven correctlly adjusted!)
I'm frustrated. I couldn't afford (can't afford) Leica lenses for the focal lengths I wanted- even used, the CV lenses <i>new</i> were better priced, but sadly, they don't produce in-focus images unless I learn to "correct" for their problems. Again, if I return them for trade and get new, I've no guarantee that I'll have anything that focuses better- my experience with LTM or M mount CV lenses is that 75 percent of the time I'll get one that doesn't focus well. (my "S" mount CV lenses are different- I've never had a complaint!)
I traded in lots of camera gear to get the M8 assuming that I'd have a decent optical system with the CV lenses. I was wrong, though I'm making arrangements for much better (and the Summicron-C is a start- until the Nokton comes back correctly adjusted from the factory!)
There is some good out of this:
I've figured out a good way to tell when a lens is in good focus that is less subjective. I use a window-screen which accurately and easily indicates where the plane of good focus is. A mark or object on the fine mesh shows the focus point. The mesh itself demonstrates a sharp plane of focus very clearly for even the 21mm.
The pictures I take with the CV lenses stopped down are pretty. I knew that when I bought 'em, and that's why I want to continue to pursue them. I'm frustrated.