Mazing occurs because the demosaicer expects green 1 and green 2 to be the same on a uniform surface, but due to crosstalk they separate and then the demosaicer starts to make up detail. The greens differs because one of the greens get most it leaks from the neighboring red and the other from the blue. Of course if you're lucky and the color you're shooting has equal red and blue content (on the raw level), green1&2 will not separate.
As Doug says it's not only about desaturation and mazing, crosstalk means that you have mixing of color channels and thus worse color separation. Degradation in color separation can be really hard to see, but if you're in medium format because of color-optimized CFA and other subtle advantages in terms of color you should think twice before wasting that advantage by mixing the channels with crosstalk.
If you want to it's really easy to take away the mazing, you just equalize the green channels. Lumariver HDR does this, and you can do it with the green equiliberation feature in RawTherapee. It's probably only a matter of time before Phase One implements it in Capture One. On the other hand mazing is a good "health indicator" meaning that you're pushing the sensor too far. If you're making a monochrome shot it will work out though.
I agree that Phase One, Hassy etc should make a thorough test of tech lenses inhouse and make the results publically available for all dealers and users to see. It's a better model than leaving it to a few select dealers and laymen. You may need to have inside information to make the tests correctly, for example with the Sony sensor it was unknown for a long time if it had offset microlenses or not (it has), which affects how the tests should be performed.
As Doug says it's not only about desaturation and mazing, crosstalk means that you have mixing of color channels and thus worse color separation. Degradation in color separation can be really hard to see, but if you're in medium format because of color-optimized CFA and other subtle advantages in terms of color you should think twice before wasting that advantage by mixing the channels with crosstalk.
If you want to it's really easy to take away the mazing, you just equalize the green channels. Lumariver HDR does this, and you can do it with the green equiliberation feature in RawTherapee. It's probably only a matter of time before Phase One implements it in Capture One. On the other hand mazing is a good "health indicator" meaning that you're pushing the sensor too far. If you're making a monochrome shot it will work out though.
I agree that Phase One, Hassy etc should make a thorough test of tech lenses inhouse and make the results publically available for all dealers and users to see. It's a better model than leaving it to a few select dealers and laymen. You may need to have inside information to make the tests correctly, for example with the Sony sensor it was unknown for a long time if it had offset microlenses or not (it has), which affects how the tests should be performed.