Archived posting to the Leica Users Group, 2017/01/07
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Sorry for the backwards information; I read your email wrong the first time and somehow concluded you were experiencing the usual back-focusing. Scotch tape and varnish fix back-focusing, and they are primarily an accommodation. The long-term fix is to change the master focus of the lens (i.e., the position of the optical unit). A little bit of front-focusing is necessary with that lens due to the focus shift when you stop down. If you set the lens to be right on target at f/2, it will back-focus for a couple of apertures. Either DAG or John can fix it. DAG might be cheaper, but it could take longer. Dante > On Jan 7, 2017, at 04:21, Peter Cheyne <peter.cheyne at gmail.com> wrote: > > Before Xmas, I sent my 90mm Summicron to a repair-man in Japan to fix the > front-focusing problem. By front-focusing, I mean that when I the > rangefinder makes it look like the lens is focussed on the eye, the focus > of the lens is actually on the tip of the nose, or even a little closer to > the lens. The repair-man said a few days ago that he took the lens > completely apart and couldn't come up with a way to fix it! > > It's back in my hands today, and, as the man said, it's still > front-focussing. > > I tried Dante Stella's suggestion of adding Scotch tape to the focus cam, > intending to add 3 or 4 coats of nail varnish if that helped, but the tape > only increased the front focussing problem. Am I right to deduce from this > that making the focus cam protrude a little more (by, say, adding nail > varnish) will bring the focus nearer? Here is a photo showing where I am > putting the Scotch tape: > > https://flic.kr/p/PHj5ho > > Without the tape, the lens is front-focussing about 2 or 3 cms from about a > 120 cms away. With the Scotch tape, this becomes worse, front-focussing by > 4 or 5 cms. > > The repair-man in Japan was recommended by a colleague who also uses > Leicas, but he is stumped at how to correct this lens. I asked Leica Japan > too, but they say they can't correct lenses that old, and don't have the > parts. I didn't know you needed new parts to calibrate a lens. I suppose > that's a stock answer for anything to do with older lenses. > > So, I don't know what to do. Am I not properly understanding Dante's > suggestion? Should I send to someone in the USA, such as Dan Goldman? What > is his turn-aroud time like, and is there anyone a little faster but still > competent? > > Still looking for advice! > > Peter > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information