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Leica SL: Focus Point Bug

Leica SL

See my Leica SL wishlist at B&H Photo.

See also How To Get Peak Sharpness With Perfect Focus in Making Sharp Images.

I reported on some focusing and focus shift issues with the Leica SL in previous posts, including two examples, one Leica SL example at 49mm and the other at Leica SL example at 90mm.

Leica contacted me yesterday. Today, after a conversation with Leica (a good back and forth exchange), a bug I reported has been confirmed (affects firmware 1.1 and 1.2). Referring to my doll’s studio setup:

Crosshair on pupil at 1X
At 6X it moves below the eye
  • In non-magnified view, place the AF crosshair dead-center on the eye, then zoom to 6X: the crosshair is now below the eye.
  • Alternately: at 6X place the AF crosshair dead-center on the eye, then zoom out: the crosshair is now above the eye.

I reported this behavior and Leica confirms it as a bug. It should be fixed in a future firmware update, but no date on that yet.

I have confirmed that *if* focusing is done at 6X magnification with the crosshair placed dead-center on the eye, then focus is spot-on. But as shown in the 49mm and 90mm examples, AFc cannot obtain correct focus on the eye at 1X (non zoomed). This I have confirmed repeatedly; no variation, completely consistent. This leads to questions:

  • Is the front-focus error shown in the 49mm and 90mm examples caused by the AF crosshair being shown in the wrong place? That is, could it be that AF is actually focusing on an area below the AF crosshair? That would be a more difficult area to focus on accurately.
  • Alternately, is the area indicated by the crosshair actually much larger, so that the AF system might pick up the wrong area?

I don’t have answers yet to these theories, nor would they explain the focus error I saw in the field. But the findings are a good place to start, and I’ll work with Leica some more on these issues, assuming they can provide me with an SL—my loaner camera was supposed to be on a UPS truck heading back several days ago, and I cannot defer returning it any longer.

The focus error without 6X zooming is a problem which even f/8 doesn’t quite fix. This small resolution chart was placed at the same distance as the doll’s eye:

Actual pixels at f/4: focusing at 1X vs 6X with Leica SL

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