Archived posting to the Leica Users Group, 2010/06/30
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Hi Geoff, thanks for your thoughts. I'm certainly not getting the pitchfork out for Solms, and am not planning on stopping my credit card payment, preferring to give them a chance to fix this. I did have a focus problem before, with my 35mm Nokton. That is OOF on all of my Ms, but not greatly so. The 'X' I describe when doing my focus test comes from laying the tape measure at a diagonal as it recedes ahead of me. So the tip closes to me would be close to my right foot, and the other tip, in the distance, would be on my left hand side. When RF focusing using these angles of my being higher than the tape, and the tape receding at a diagonal across the floor, the two images sen on the RF patch are not quite parallel but intersect at one point. If they were parallel along the length of the tape, I would not know whether 300cm is the point of focus, or, say 303cm. Give it a try and you might see what I mean rather than trying to imagine it. I know that the focus jigs the techs use are sloped away verticaly, and I might have done that if I had a moveable screen at hand, but I don't. the tape measure receding into the distance diagonally is working for me. Looking at my test shots, especially at the 1m and 2m distances, it is very obvious which cm mark the lens is actually focused on, and the thick crayon marker makes clear where I had focused the RF. The discrepancy between them is therefore plain. I do not claim to judge the exact discrepancy in cms or as a percentage, because I did not see the need to workout the trigonometry. I do see that if the tape measure shows a 25cm distance along the tape between the point of the lens' focus and the point the RF was focused on, then the discrepancy os not actually 25cm, because I am standing above the receding tape and aiming down at an angle. Anyway the photo itself shows the problem is a big one, absolutely, and relatively to my other tested lenses (even the Nokton, which is also front-focusing). Basically, all my lenses are now acceptable apart from the 35 Nokton, which I will deal with one of these days, and the 90mm Tele-Elmar, which was one of the lenses sent back as adjusted by Leica. I am getting very accurate results from my 135/2.8, my 135/4, my 90/2, and my 50/2. Not only are these results very accurate, they are repeatably constant. For example the 135/2.8 focus is bang on, dead centre in the middle of the depth of field spread. The 50/2, which was returned yesterday from Solms, is acceptable, but not as accurate, consistently front focusing a bit, but staying within, although to the back of, the depth of field spread. It is not dead centre of focus at any aperture at any distance, but I can live with that. With these consistent results, I am not looking for another person to verify my results. Two out of 6 lenses are front-focusing. I knew about the Nokton already, and it was discussed on the LUG. The other one is a recent problem, since I got it back yesterday. It was a bit off when I sent. That's why I sent it. Andrea Frankl told me by phone that they could see to it for me, gratis. I'd told her they were older lenses. The reason for the price hike from 0 Euro to the eventual 300 odd Euro is that the technicians told her they always have to do something to the lens focus mechanism to comply with the very thin depth of receptivity had with the electronic sensor. She hadn't thought of that when she offered me the service gratis, admitted it and apologized. I gave her the go-ahead anyway, seeing as my lenses were by now with them. She got the technicians to reduce the price by 100 Euro per lens, which is why it became 314 or Euro per lens, rather than 414 or so. Her offer was nothing to do with expecting my lenses to be in warranty still. I sent the lenses after the camera, on Andrea's suggestion. They were to be looked at together, although she assured that because of the standards they use, this would not be necessary. However, they would look at them together anyway. However, I do not know if the technicians agreed with that. They might not have tested the 90mm lens with my M8, for all I know. Thanks for thinking this trough. Someone else sent me a message off list saying I would do well to see it through with Leica, who often get it right every 1.5 times - as in, if they don't get it right first time, they make good second time. So that is what I am going with for now. I will wait for Andrea Frankl's reply (or her colleague's, Andrea is out of the office until mid-July but her mail is being forwarded to a colleague, I think). I'm also interested to reading the technician's comments on the test photos I sent in. I'll report those, if and when I get them. All the best, Peter Cheyne