Voigtlander FE 35mm f/2 APO-Lanthar Aspherical Aperture Series: Deck Planks and Ruler Focus Shift Evaluation
Related: apochromatic, optical focus shift, Voigtlander, Voigtlander FE, Voigtlander FE APO-Lanthar 35mm f/2 Aspherical, Voigtlander Lenses
Update May 6: see Voigtlander FE 35mm f/2 APO-Lanthar Aspherical: what looked like inexplicable focus shift is shown in part to be Focus Creep / Unstable Lens Focus.
Original post...
This aperture series from f/2 through f/8 takes a critical looks at focus shift with the Voigtlander 35mm f/2 APO-Lanthar, finding some surprises. Well, not entirely—I had seen oddball sharpness results with stopping down in some other series at greater distance, so I decided to investigated—sure 'nuf.
Voigtlander FE 35mm f/2 APO-Lanthar Aspherical Focus Shift Evaluation Planks
Includes images up to full camera resolution plus crops.
I’m dumbfounded at the results as I expected no focus shift—but I can repeat at-will on varying subjects. Users of the Voigtlander FE 35mm f/2 APO-Lanthar will definitely want to be aware of this behavior. Maybe it is a weird sample? I haven’t seen behavior like this before.
Another example, with a ruler in millimeters for seeing the shift in a more obvious way:
Voigtlander FE 35mm f/2 APO-Lanthar Aspherical Focus Shift Evaluation: Ruler and Soil
I have a 2nd sample coming in two days that I can also test to see if it somehow sample specific. I doubt that, but very high performance designs possibly could do weird things if off just a little. But if so, I cannot explain the razor sharp 'cut' this sample makes at f/2 across the frame.
Deck planks are warped as seen—this is not optical distortion.
Sony A1 + Voigtlander FE APO-Lanthar 35mm f/2 Aspherical RAW: +30 Whites, +15 Clarity
[low-res image for bot]
