fbpx

LEicA m

TEST AND EVALUATE
FOCUSING ERRORS

Focusing errors in a Leica M system can occur from either the rangefinder mechanism in the camera body itself or it can be a lens issue. This may make identifying the source of front- or back-focus issues tricky.
I have listed 4 options to come closer to a solution and to identify where the problem is. Troubleshooting in this order to test your camera and lens.

  1. First, try different lenses on the camera:
    If you have access to two or more lenses, especially one of them known to be accurate on a different body, perform a focus test.
    Do this at 1 meter with that lens because that’s the ideal focal length. If the new lens is accurate, your rangefinder probably is good, and this shows that the original lens may need adjustment.
    If both lenses show the same out-of-focus problem, it likely is the camera’s rangefinder needing calibration.

  2. Secondly, check some different distances:
    A rangefinder misalignment may not be consistent at all distances, and therefore testing only at 1 meter can be misleading if the rangefinder mechanism is slightly off at close range or if a lens exhibits focus shift. Try making a test at 2 meters, 3 meters, and also near infinity focus.  

  3. Thirdly, you can try to look at the patch alignment: Having the rangefinder patch squares nicely lined up in the viewfinder usually means vertical alignment is okay, but horizontal alignment can still be off, causing front- or back-focus when the patches overlap. Check at infinity by pointing at a distant object (over a few hundred meters) to see if the patch aligns perfectly. If it’s off at infinity, the camera’s rangefinder alignment is likely the issue.

  4. Finally, a lens-specific focus shift can be an issue: Some Leica M lenses, especially modæes with a fast aperture like f/1.4, can exhibit focus shift when stopping down from wide open. A test wide-open might not match real-world shooting at f/4 or f/5.6; therefore try a shot at a typical shooting aperture. If the focal plane moves as you stop down, it’s lens focus shift, not a rangefinder misalignment.

What to do?

  • If one lens persistently shows a focus problem and others do not have that lens serviced by Leica service.
  • If multiple lenses misfocus, send in the camera for calibration.