Z5 vs Z6 for Adapted Rangefinder Lenses

beatboxa wrote:

GCL wrote:

Thanks for your reply and resources.

I appreciate that the purpose of the BSI sensor is to improve processing speed, but I have read in several places that an unintended additional consequence of a BSI sensor is that the sensor stack thickness is reduced and therefore rangefinder lenses perform better on BSI sensors (all else being equal). Those who use a lot of adapted manual focus lenses, particularly rangefinder design lenses, generally describe Sony A7x cameras as the worst performers with adapted rangefinder lenses, with a 1.9mm thick sensor stack, and Nikon Z6 and Z7 as the best for adapted lenses, with a 1.1mm sensor stack (and with Panasonic and Canon as in the middle - around 1.45mm for Panasonic, some have reported).

The theory as other have expressed it is that the placement of the circuitry above the photodiodes increases the thickness of the sensor stack and therefore degrades the corner sharpness and causes corner color shifts of images with adapted rangefinder lenses.

Good illustrations of the differences between BSI and FSI can be found here:

https://www.stemmer-imaging.com/en/knowledge-base/vorder-oder-rueckseitig-beleuchtete-sensoren/

Either way - theory aside and not everything necessarily being equal - I thought it would be interesting to hear from anyone who has adapted a manual focus lens, preferably a rangefinder wide angle lens, to see if they saw any performance differences between a Z5 and Z6.

The sensor stack referred to as effecting optics is (again) the glass in front of the sensor, not the thickness of the electronics in the sensor itself. You are conflating the sensor electronics for the optics in front of it.

Even in your own link, it notes 2 things:

1. The microlenses are what direct the light toward the photosensitive area. The illustrations even show all of the light being counted in both the FSI & BSI.
2. Pixel size has to be between 1-2 μm before BSI delivers more light efficiency than FSI

The pixel size of the Z5 & Z6 are around 6 μm, much larger than this 1-2 μm range in your own link. Even the Z7 has around 4.3μm (still much larger). You'd need around a 200MP-400MP full-frame camera before the optical benefits begin to make a difference, according to your own link.

So again: I think the sensor stacks will be similar, as will performance. It's not just adapted rangefinder lenses--it's all lenses for a mount from the brand. They tend to keep sensor stack thickness similar for these reasons.

Great to read your analysis - thank you! Do you think there would be any significant difference in high ISO performance (i.e., noise) between the Z5 and Z6 sensors?