For some reason my summicron 50/2 will not focus at infinity so I decided to take the lens down so I could get to the cam, after trail & error aligning the cams (Those of you who have been there know what this entails)I managed to correct the problem, I think , the infinity mark on the lens barrel does not coincide with the focusing ring it goes past apron 5mm & likewise at the closest 0.7 stop, I can now focus at 0.6, Should I send the lens in or just live with it. Any comments on the above will be warmly met.

Happy Easter to all.

Paul

Paul

-- paul (longrange@swipnet.se), April 13, 2001

Answers

If this were an SLR you'd have no problem as the focus is visual, what's sharp on the screen is sharp on film. But the rangefinder is focus-by-proxy so things have to be calibrated to one another. My Summicrons (and others as well) go a little past the close-focus (0.7m) mark, that's no problem. That is also goes past infinity may or may not be a problem, depending on if the rangefinder can still focus the lens accurately. If you sight on a sharply-defined vertical-line target (like a TV or radio tower) at least a mile away, and rack the lens until the rangefinder images are merged, does the lens register at the infinity mark or beyond it at the end of the ring's travel? If it needs to be all the way to the past-infinity stop, then it will be "off" at every nearer distance. If at the past- infinity stop the rangefinder images begin to separate again, you might be ok. But the only real way to tell is to shoot a test roll or tape a ground glass in the film gate with the back open and the shutter set to "B" and locked open with a locking cable release, then use a loupe to check focus.

-- Jay (infinitydt@aol.com), April 13, 2001.

The best way I found to check real focusing accuracy is not with a ground glass and lube, but by setting up several objects close together in a row from near to far and carefully focusing on the one in the middle at a wide aperture. When the negs/slides come back, it will be pretty obvious if the camera is front or back focusing and if the lens needs adjustment. Alternately, you can focus on a chart or some other flat detailed object, and "focus bracket" slightly before and after the indicated point given by the double image. If one of the before or after focused shots is sharper than the one in the middle, your out of whack.

-- Andrew Schank (aschank@flash.net), April 13, 2001.

Paul: I agree with checking the infinity position. On the close focus, I lay a tape measure on the floor, mount the camera on a tripod and shoot at about a 45 degree angle towards a reference point on the tape measure (a piece of paper with an arrow will do). I then shoot a test roll and check it with a loupe, slide projecter or enlarger depending on the film used. This tells me if the lens is off, how much and which direction. Be sure to shoot wide open for accuracy. You can determine if the error is acceptable based on how much you shoot with the lens wide open. Another way is to find someone else with an M and compare the two. This is not as accurate, but good for a crude check.

Cheers.

-- Mark A. Johnson (logic@gci.net), April 13, 2001.

It is a simple adjustment that requires special tools to do correctly. I had my fifty CLAed and the focus cam adjusted by the Kindermann Canada for about $80US. It now works and couples perfectly and the repair was just too inexpensive to consider doing myself. It is possible to do it yourself but it is difficult to get it right without endless disassembly, reassembly and testing. The tools make the adjustment quick and accurate. Sometimes a good Leica repair person is the simplist and least expensive option.

Cheers,

-- John Collier (jbcollier@home.com), April 13, 2001.