Nikon Z 24-200 f/4-6.3 compared to Canon RF 70-200 f/4

Started 8 months ago | Discussions thread
z2122 Senior Member • Posts: 1,825
Re: R5 has AA filter and Z7II does not...

kenw wrote:

DaveR43 wrote:

starbase218 wrote:

You can’t compare across systems, even if the sensors are the same resolution.

The tests used same chart, the same test conditions (lighting etc), same sensor resolution.

How would you explain the differences in results?

The R5 uses an AA filter and the Z7II does not thus the Z7II will always report a higher MTF50 than the R5 when using the very same lens. That's why comparisons across systems don't work well. You aren't testing the lens - you are testing the lens+camera and there is more going on than just sensor resolution (i.e. pixel pitch).

Besides the AA filter there is the effective fill factor of the sensor. A lower fill factor results in slightly less sensitivity for the sensor but an increased MTF50 (and aliasing) for the sensor. In fact some testing has shown the Z7/Z7II likely do have a slightly smaller fill factor than other sensors of the same resolution.

So here we are getting a double whammy with the R5 having an AA filter and the Z7II having a lower fill factor. This means that even for identically performing lenses the Z7II will show a higher MTF50 than the R5.

You can see this effect in the plots posted. By F/22 the center resolution is going to be totally dominated by diffraction and not really depend on the lens design at all. Notice that for the R5 shots the center resolution is right around 2000 LW/PH at every focal length at F/22. For the Z7II it is right around 2500 LW/PH.

your explanation is good , but at the end the whole system counts and not only the lens.

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