Reader Alfred W writes:
Question: Would the Z7 be as good as the D850 for monochrome conversion? Is the glass over the Z7 sensor a problem?
DIGLLOYD: short answer: the D850 is a better choice for being assured of the absence of PDAF pixel issues, because its sensor is free of the PDAF pixels found on late model mirrorless cameras like the Nikon Z7, Sony A7R IV, Canon EOS R5, etc.
Dan Llewelyn at maxmax.com confirms that the Nikon Z7 can be converted to monochrome and he’s done so. But like the Sony A7R IV and all other late-model mirrorless cameras today, it has on-sensor PDAF pixels, which might show up in some images as PDAF banding.
...with any Sony / Nikon PDAF sensor that uses the 1/2 masks for PDAF will show them under some conditions.
I am unsure how much of an issue this is, as I have not yet shot any converted mirrorless camera with a PDAF-containing sensor. However, even in color (unmodified), the PDAF pixels can be troublesome, such as on the Sony A9 and on the Fujifilm GFX100.
A sample image from a Nikon Z7 Monochrome is shown below. Regrettably it is at ISO 800 so it is fairly noisy. There might be some undesirable patterning to the noise—see the letters of “Chemical”. OTOH, it is sharper across the field than what I saw coming out of the Leica M10M.
On the other hand, I can attest to the freedom from digital artifacts with the D850M*. As can any of my readers, who can examine the full-res and even double-res (180 megapixel) images in my Nikon D850 Monochrome review. I value impeccable image quality across the most demanding scenarios, so the black-dot pimples of the Leica M10 Monochrom are unacceptable to me. And the far superior lenses for the D850 yield far greater total real resolved detail.
I am hoping to get a donated Sony A7R IV to convert to monochrome in order to definitely answer the questions on image quality, but no decision yet.
* Could I have missed something? I suppose so but it would have to be subtle and rare.
7860 size is 41 megapixels, about the same as the Leica M10 Monochrom image size.