I recently got a 28mm screw-mount Voigtlander and the adapter to fit it on an M-mount Leica. When I insert the adapter as instructed, then screw in the lens, the lens tightens with the dots on the D.O.F. scale and the aperture ring just a few degrees beyond 12 o'clock, i.e. not exactly plumb. I'm shooting a test roll to try to see if this apparent misalignment has any effect on focus (although with a 28, it might be moot), but I wonder if anyone else has seen this and, if so, is it going to present a problem with critical focus when I am 2.5 feet away and F:1.9?

-- Michael Stern (hoof@optonline.net), March 19, 2002

Answers

I have the 15mm Voigtlander and it screws just one millimeter short of the center. I have heard that it is quite common especially with the Voigtlander adapters (less so with Leica's own) that they don't fit the lens exactly in the top middle. If it is a large difference, say a few millimetres off the top of the lens, then the lens hood might vignette. I would try another adapter if the difference is big. And a Leica one as well if nothing else helps.

For critical focusing the difference is actually quite small because the screw is about 0.75 mm/turn and 5 degree difference would thus only be 0.01mm in extension.

Ilkka

-- Ilkka Kuusisto (ikuu65@hotmail.com), March 19, 2002.

Michael,

it doesn't have to be the adaptors fault; I personally own some LTM - lenses of which only a russian one (!) fits at 12 o'clock - regardless of the Leica or 3rd-party adaptor. But nothing to worry about, since focus is dealt with via rangefinde coupling - you can even take in-focus pictures with the lens a turn off if the coupling is still there. So the only problem might arise at fous-ends of the lens.

BTW, even Leica LTM lenses might not fit perfectly - but make perfect pictures (with a perfect photographer).

-- Kai Blanke (kai.blanke@iname.com), March 19, 2002.

I had the same problem ONLY using VC lens on Leica adapters (I used three adapters), but NO problem using VC lens on VC adapter (there will be a reason?). I read, some years ago, perhaps on this forum, that when the center of the lens (the dot of DOF) doesn't coincide with the center of the bayonet, should be problems in terms of vignetting (I don't remember problem with focus). Maybe a casualty, but using a 15mm VC on a old Leica adapter with the problem of misallignement, I destroyed a roll of slide: all had a very very strong vignetting. After that, I used a VC adapters, on the same lens, without no more problems.

-- Domenico (Giandom@comune.re.it), March 19, 2002.

I did tests on this--you can do it yourself by simply opening the camera back and looking throught the lens from the corners of the frame with the shutter open while turning the lens, looking for the hood to move into view. The 15mm lens needs to be rotated so one of the f8 depth of field marks is at 12 o'clock before there's hood vignetting. Remember, the 15 has a lot of vignetting on it's own, with no help from the hood.

On the 28mm, you just turn the hood so it's straight. Position of the lens, within reason, when seated has nothing to do with focus, since that's determined by the thickness of the adapter, not the placement of the threads in it. Think about this point--a lot of people don't get it immediately.

If your lens is so far off that you just can't stand it, remove the screws from the back of the mount, turn the mount accordingly, and put the mount back on into a new set of screwholes (there's a series of them on the back of the lens under the mount, about 5mm apart, specifically for centering the lens.) Don't lose any shims, if there are any, and move them as necessary to the new set of holes.

None of my LTM lenses center on my IIIa or on any of the mix of M adapters I have (three different brands, and newer and older Leitz).

-- Michael Darnton (mdarnton@hotmail.com), March 19, 2002.

Michael, I have the same problem using Canon LTM lenses (f1,4/50 and f1.8/50), one Zeiss Sonnar 50mm with LTM, Voigtlaender LTM lenses and use a Leica IIIf, a Bessa R, and a M4-P and a M6. And my Leica Elmar 4/90 is also a few degrees beyond 12 o'clock, but not on the Bessa R, only on the IIIf. The Canon bodys, P, 7 and VI-T (I'm collector also) are the worst - but with Canon lenses, Voigtlaenders are fine on Canon bodies. But I never had a problems with the focus - not for this reason.

-- Richard (richard.srienz@swissonline.ch), March 19, 2002.

Thanks to all who responded. I feel a lot better, and the pictures I took today at F:1.9 at .7 meters appear sharp. As Michael Darnton pointed out, Position of the lens, within reason, when seated has nothing to do with focus, since that's determined by the thickness of the adapter, not the placement of the threads in it.

-- Michael Stern (hoof@optonline.net), March 19, 2002.