Leica SL3: Unstable Lens Focus with 4 of 5 Leica APO-Summicron-SL lenses
Related: apochromatic, botched design, imcompetence crisis, Leica, Leica 35mm f/2 APO-Summicron-SL ASPH, Leica 50mm f/2 APO-Summicron-SL ASPH, Leica 75mm f/2 APO-Summicron-SL ASPH, Leica 90mm f/2 APO-Summicron-SL ASPH, Leica APO-Summicron, Leica APO-Summicron-SL, Leica M, Leica SL lenses, Leica SL3, Leica Summicron, Leica Summicron-SL, unstable lens focus
re: botched design
UPDATE: I now have proof of the same unstable lens focus behavior on the 24MP Leica SL2-S, showing that it is not a camera-specific problem. It could be a single-sample problem except that both the 75/2 and 90/2 both show the same bad behavior. So it is not just one lens. Moreover it’s erratic/flaky. OTOH, so far it appears that the 28/2 APO, 35/2 APO, 50/2 APO are free from the issue, or at least I cannot be sure.
UPDATE 2: unstable lens focus is also seen with the 35/2 APO and 50/2 APO. The issue also manifests with the Leica SL2-S, so it is not camera specific either, and looks to be a system deficiency that makes the Leica SL system dead on arrival for numerous types of photography—any work where more than one frame is taken without refocusing.
UPDATE 3: the 28/2 APO might also have the issue. Less frequent and less common but I have two series that show a change in one of the apertures. In other words, the issue is systemic at least for the vaunted APO-SL lenses.
...
I was puzzled at the extra-strong focus shift of the 75/2 APO as shown in Deck and Roof, strong to the point of ridiculous. This seemed wrong optically, yet it was consistent with the the direction of the focus shift and the field curvature in Yellow House at Dusk. Seemingly bearing no explanation other than optical focus shift.
And yet, I now have proof that the focus shift is largely the result of unstable lens focus, making it unreliable to take more than one frame without the focus glitching to the distance with each frame (but sometimes/often and not always). Flaky and erratic. At least with the 75/2 APO and 90/2 APO and 35/2 APO and 50/2 APO.
Leica SL3: Unstable Lens Focus
Leica 90mm f/2 APO-Summicron-SL ASPH Apeture Series: Deck and Roof
A camera this unreliable is an unprofessional toy. Stay away from the Leica SL3 until Leica fixes this problem is my advice. If it can be fixed—what if it is lens electromechanical issue and not fixable? The good news would be a firmware fix, if that is possible. However, my expectation based on past experience working with Leica is for Leica to ignore the issue.
Below, unstable lens focus: these are both f/2 and focus should be identical! 12 foot / 3.6 meter focus drift.
LEICA SL3 + Leica 90mm f/2 APO-Summicron-SL ASPH
RAW: Enhance Details, +10 Whites, +10 Clarity, AI Denoise 10, +10 Vibrance
[low-res image for bot]
