90 Cron AA doesn't go to infinity

[nephilim]

Hi!

A few weeks ago I sent my whole kit to Leica CS in Solms in order to get some things fixed. I bought almost everything used, so the M7 got the optical DX reader, the 50 Lux ASPH focus ring runs smoothly now and the 90 Cron AA no longer back-focusses. Everything was adjusted and calibrated. I'm very happy with the result except one thing which seems odd: the 90 Cron no longer reaches infinity, i.e. the rangefinder patch moves into the correct direction for distant objects but the two images don't fully match. A tiny bit of range seems to be missing. I don't remember that this happened before the lens went to Leica. Is this something which I should worry about?

Cheers,
Torsten

[ampguy]

I wouldn't worry about it, as long as when the lens is at infinity, infinity is sharp.

If you send it back, they will likely align it so infinity on the lens matches infinity on the VF/RF patch, but then your close focus may be off again.

[Rowse]

I just posted the same issue with my 50mm Elmar. When the lens is focus at infinity there is still a split image in the rangefinder patch when using my MP. A hair or two of focus room is needed to make the images coincide into one. But on my M7 the split images line up perfectly. I will wait and see how my scans look before taking any action to correct the problem.

[nephilim]

Many thanks for the replies! I also fear that sending it to CS again might result in a faulty close focus behaviour. I don't remember any faulty infinity shots but just spent the last frames of the current roll to check if there are any real world issues. When the images look ok, I'll stop bothering.

Frank, so in your case it depends on the camera? Maybe we should exchange our M7s ;-)

[Pherdinand]

thats pretty much a bummer on such an expensive kit. I would expect top performance both from camera and lens, not some tiny bits of misalignment here and there!

[ferider]

With a 50/2.8 a small discrepancy is no problem.

With a 90/2 it can be the difference between unsharp and sharp, in particular if one spends the extra money for an AA lens. Wide open, the 90/2 has the thinnest DOF of all Leica lenses, similar only to the 75/1.4. Hyperfocal distance is 135m, meaning you have to be able to see a difference between 135m and infinity in the viewfinder.

Your problem shouldn't happen with the camera/lens coming back from Leica. I would definitely have it looked at.

Roland.

[bwcolor]

I have the same lens and it seems to focus properly near/infinity. Having said that, I have two lenses out for a backfocusing problem and two bodies back to Zeiss for infinity alignment. I would send it back.

[awilder]

The 90 AA is quite sharp and DEMANDS accurate syncronization of the lens cam and body rf to get the most out of the lens at f/2. If the rf is off enough to be noticable without a finder magnifier I would send it back to correct this under the repair warranty. The nice thing about Leica is that if you paid for repair (and I'm sure it wasn't cheap), they warrant their work for a year. It's very easy for you to play with the infinity adjustment on the rf roller but if the 1 meter adjutment also needs tweeking, you might as well have them do it under warranty as that's a little more tricky.