Archived posting to the Leica Users Group, 2005/09/10
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Well, ... I have some test slides back and have done some calibration tests of the body and the 35/1.4 Asph lens, and ... it all appears to be OK! Which is absolutely amazing given the state the lens hood was in. But I guess it acted like the crumple zone in a well designed car. I thought I'd pass on the method I used to verify the focussing accuracy of the body and the lens, as it might be of use to others. To check close range focussing accuracy of an M body: 1. Remove the back. Place the body on a tripod pointing at the floor about a meter up. 2. Get a focussing screen from an R camera and lay it gently on the film guides. The side of the screen that would be up and closest to the pentaprism in the R body should be facing down and lying only on the two inner film guides of the M. It will need to be on a diagonal, supported at the corners. Don't get yer sticky fingers on the focussing screen if you like it. 3. Fit a good lens of verified performance. A 90mm is a good choice. Open it right up. 4. Put a business card on the floor under the lens or something else to focus on. 5. Using a 35mm lens as a loupe, focus using the ground glass screen. Then check through the rangefinder. Given that the lens is good, if the rangefinder is bang on, the body is also good at this distance. 6. Switch to the 'dodgy' lens. Repeat focussing tests. Note that it can be really hard to see fine detail on the screen with a wide angle lens fitted. Use a higher power loupe, such as a 24 or 21mm lens. To check distance focussing accuracy of an M Body: 7. Find a window with distinct, distant object. Church steeple at 1 km would be good. 8. Hold the focussing screen in place using two rubber bands looped around the body and small rolls of soft material as packing against the focussing screen. This gentle tension will keep the screen from falling when you lift the tripod head to face the body out into the horizontal distance. 9. Do the same tests as before. If focussing screen and rangefinder give consistent results, chances are everything is hunky-dory. :-) Rick.