I have a 50mm Summicron M that appears to be front-focusing consistently by an inch or two at closer distances.

After getting some softer results than expected I did some tests. With my M3 my other lenses seem to focus fine, but the Summicron is indeed off, as confirmed by the film test (row of books at 1.5m, several a different depths, sequence starting wide open).

My question is, is it possible for a lens to be out of adjustment such that it does not engage with the rangefinder accurately? Have others encountered this problem? This is a new production lens less than a year old and still under warranty.

Thanks.

-- Gary Voth (garyvot@vothphoto.com), April 13, 2002

Answers

The answer is yes, but not likely.

The more likely scenario is that the lens is also off at infinity, regardless of what the RF says.

Since its only the one lens that gives grief, then its prolly not the camera, however there is at least one adjustment (maybe more) that will tweak the linearity of the rangefinder in the camera (ie track from close to far).

Check the lens critially at infinity (wide open) and see what you get there.

-- Charles (cbarcellona@telocity.com), April 13, 2002.

Yes, it is possible, and as Charles said (unless somebody mucked up with the cam) it will be out at infinity as well. It should focus down to its minimum focus distance without any problems. I usually check them at 80cam, 1,5m and 50m. For closeup tests a tripod is a must, (in case you haven't used one). I had similar experiences with 2 brand new lenses (50/2 and 50/2.8), and now test any lens I buy regardless of make, new or second hand.

-- sait (akkirman@clear.net.nz), April 13, 2002.

Thank you.

I know the M3 rangefinder is okay; it just came back from Leica for adjustment and I had it independently checked by a local technician.

Yes, I used a tripod, bubble level, cable release, etc. I can tell that it's a focusing problem because the intended plane of focus is soft while an object in front of it is not.

I guess I will have the lens checked and serviced.

-- Gary Voth (garyvot@vothphoto.com), April 13, 2002.

I had the same problem - it was everything else but the lens; the film pressure plate was bent slightly which moved the film away from the lens = focus was closer than RF. Also the lens mounting flange on the body was bent = the lens wouldn't line up with infinity. I did some reseting of the cam at first using a ground glass screen on the inner rails and a 15x loupe - this just isn't accurate enough for critical focusing and I had to do a set of actual film tests. I eventualy got it right and bent the pressure plate and lens flange back to near true ( I'm putting an order in to Leica UK for new ones). What i have found is that the tolerance needed on these cameras to focus accuratley is very small - even a very slight error or misaligned part will thow it out.Get it back to the dealer and get it fixed is my advice.

-- John Griffin (john@griffinphoto.u-net.com), April 13, 2002.

Wow John, that sounds like an adventure. I sympathize.

I believe the camera is okay because it is focusing my 50 Noct and 90 Suumicron ASPH just fine; these lenses should show any misalignment in the camera or rangefinder.

Random editorial comment: I've only recently started shooting with the M after 25 years with SLRs. One of the things I've always lamented about the shift to AF is the loss of simplicity when it comes to shooting problems. With my Canon F-1s, if something was out of focus I knew it was my fault. Whenever I get unexpected results with my EOS gear, there's always a nagging question about just what went wrong, whether a body or lens is focusing improperly, etc. It looks like shooting with the M may not be too different in that respect...

-- Gary Voth (garyvot@vothphoto.com), April 13, 2002.

Hi Gary,

Yes, there is the possible that the focus shifts a little. This problem often happens in old lens.

In my point of view, the reason is that the focus threads in the lens are out of tolerance. There is clearance in the threads. When you turn the focus from infinite to a desired distance or from near distance to the desired distance, you should get different readings at the lens distance indicator.

Using a lens test target, take shoots by focusing the lens from different directions, after processing the film, you can know which is accurate. When you take photos next time, you must turn the focus from the accouate direction tested.

My old 50mm M-Summicron lens has the same problem. I have found turning the focus from infinite to the distance is accouate. So I just use the lens by focusing from that direction.

Hope I could help.

WEN

-- WENGE SONG (w.song@qut.edu.au), April 15, 2002.

Gary, Ihave encountered same problem when I use the NEW silver chrome 50mm crons on the M3, no problem on M4 & M6. But I did tried shooting at F2.8 speed 1/250th secs hand held of a glass tower some 600 M away with the M3 and this same lens many shots. Result: the image on 4R prints looks sharp with 10x magnification, the vertical lines were sharp & clear. I shoot the same tower a few days later at F5.6 and speed 1/500th secs and all other shots with the same setting. Results: all the images on print were consistently unsharp even at 4X.

-- Quek Khai Liang (liangkhai@hotmail.com), April 19, 2002.