It turns out that the 1.1mm figure from KolariVision for the sensor cover glass does not include the expoxied-on glass portion of the sensor. So the real figure is ~2.3mm total glass thickness, not 1.1mm (Nikon D850 is about ~2.5mm). Still 2.3mm is notably more thin than the 3+ mm for Sony mirrorless. In other words, performance of lenses designed for Leica M *will* be degraded on the Nikon Z7 but notably less than on Sony. But how much will depend greatly on each lens and its particular optical design—no generalizations work.
Studying fine text that approaches sensor resolution in Live View at the edge of the frame at f/1.4 on the 45-megapixel Nikon Z7, performance look promising—seemingly better than many ordinary f/1.4 lenses on their native platforms. The edge of the frame is where the depradations of ray angle are of greatest concern and yet I am not seeing any obvious astigmatism or blurriness or smearing at f/1.4, which means that the Zeiss ZM 35/1.4 is at the least a very good performer on the Nikon Z7 at f/1.4. Sub-optimal surely, but clearly highly useable wide open.
See MTF on Mirrorless Cameras for an MTF series from f/1.4 through f/16 as measured by Zeiss for its effects on lens performance.
By comparison, I am seein pronounced (beyond unacceptable) quality losses with the Leica 24mm f/3.8 Elmar-M ASPH which had even worse issues on the Sony A7R back when I tested it in 2014. The good news is that the hideous magenta cast seen on the A7R does not exist on the Nikon Z7. Still, the sharpness loss is so severe that I deem the Leica 24/3.8 non-viable at any aperture.
The haptics of the Zeiss ZM 35mm f/1.4 Distagon have always been superb, but on the Z7 it’s a pairing unrivalled by any other camera/lens I can think of: haptics of the lens and its size/weight/balance on the Nikon Z7. At least for my largish hands. The EVF of the Z7 is incredible, making the Leica M240 look like the museum piece it is (24 megapixels with a crude low-res EVF that can only zoom in the center—it’s day is over).
My full report on Leica M lenses and Zeiss ZM lenses means lens reviews, which go into their native publication (diglloyd Leica) as has been the well-reasoned and rational organizational system for years. However, I intend to cover the general topic of M/ZM lenses on mirrorless with examples in diglloyd Mirrorless, at least for the Nikon Z7.
I wrote to my contact at Zeiss with this question:
If the Nikon Z7 has 1.1mm cover glass, then it seems likely that the Zeiss ZM 35/1.4 might perform reasonably well even wide open, and very well by, say, f/2.8?
The response was in the affirmative: “Everything correct, fully agree”.
There will surely be some minor impairment for the first aperture or two, but 2.3mm-thick sensor cover glass is a a lot less damaging to image quality than 3+mm-thick sensor cover glass as with Sony.
This looks to make the Nikon Z7 the pre-eminent high-resolution mirrorless platform for anyone looking to adapt lenses: Nikon F-mount with the superb Nikon FTZ lens adapter, Leica M and Zeiss ZM and Voigtlander lenses with an M-to-F-mount adapter (one already exists) and just about everything else.
The Nikon Z7 has the best resolution, best EVF, best ergonomics/haptics, all without the performance-killing thick sensor cover glass of Sony mirrorless. Its compact size and superb feature set and image quality along with compact Leica M and Zeiss ZM lenses holds huge appeal—though I don’t think some Leica M lenses will be good enough for a 45MP sensor.
Coverage of Zeiss ZM and Leica M lenses or any lens always g into the native guide for the lens that is covered, e.g.,diglloyd Leica. Subscribers to the FULL ACCESS deal of course have full access to that and everything else.
- All about the Zeiss ZM 35mm f/1.4 Distagon
- Zeiss ZM 35mm f/1.4 Distagon: I rate it the best M Lens Available
- Zeiss ZM 35mm f/1.4 Distagon on Leica SL — a Joy to Focus and Still the Best Overall M Lens