SOOC jpgs, but they are already telling a compelling story.
To recap, I have an A7R4A which was modified for full spectrum monochrome, and I wanted to check for IR hot spots. A bit of GAS led me to compare:
Voigtlander 35mm f/1.4 II SC Leica M
Zeiss Biogon 2/35 ZM
Voigtlander 35mm f/2 APO-Lanthar M
Zeiss Distagon 1.4/35 ZM
The filter was a single 49mm Hoya R72, the CV 35mm f/1.4 II SC and the Biogon used a step up ring, while the filter screwed onto the Apo-Lanthar and the Distagon without a step-up ring.
I am not at all surprised that the SC-coated CV has a hot spot (at f/16) and that the Apo-Lanthar is clean. But I am surprised by the difference between the Biogon and the Distagon. I had assumed that their performance was going to be dominated by their T* coatings, so if one was going to be bad/ok, the other should be bad/ok too. But that is not at all the case. Ok, not a big deal, it just confirms my motivation to do this test. And I am fine with one character lens for regular monochrome shooting and a separate lens for IR. It looks like it will be the two CV lenses, but I'll do a couple more tests to verify.
Pics below are in the same order as in the list above. Top frame is f/2 and bottom frame is f/16.
Nov 01, 2025 at 03:21 PM
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