05-20-2011, 12:24 PM
[quote name='popo' timestamp='1305892577' post='8682']
While doing away with the AA filter may be a little questionable, this 15x3 foveon would need a weaker one than a 15MP bayer. I note Sigma are saying they don't need AA to prevent colour moire effects, implying they think moire is ok if it's equal between channels. I can kinda see where they're going, if we draw parallels colour noise is generally considered ugly, but luminance noise isn't so.
The price certainly does kill it as far as I'm concerned.
[/quote]
They do not need a weaker one, they need an exact same one as with a bayer CFA. Optimal strength of AA filters has nothing to do with the CFA filter below it, only with the fact that details in the real world do not start and end on pixel borders.
Foveon sensors have the SAME aliasing problems as Bayer CFA sensors.
Foveon sensors have the SAME luminance moire problems as Bayer CFA sensors.
Foven sensors do not have the same chromatic moire problems as CFA sensors.
Manufacturers who use AA-filters do not do that to prevent chromatic moire problems, but to prevent the false detail to be recorded. That that also prevents chromatic moire effects is a bonus.
Moire patterns are considered very ugly, also from foveon sensors.
Aliasing is considered ugly too.
It is fine to make the choice to not use AA-filters (same as Leica does), but I do not like their bogus marketing speak nonsense,
While doing away with the AA filter may be a little questionable, this 15x3 foveon would need a weaker one than a 15MP bayer. I note Sigma are saying they don't need AA to prevent colour moire effects, implying they think moire is ok if it's equal between channels. I can kinda see where they're going, if we draw parallels colour noise is generally considered ugly, but luminance noise isn't so.
The price certainly does kill it as far as I'm concerned.
[/quote]
They do not need a weaker one, they need an exact same one as with a bayer CFA. Optimal strength of AA filters has nothing to do with the CFA filter below it, only with the fact that details in the real world do not start and end on pixel borders.
Foveon sensors have the SAME aliasing problems as Bayer CFA sensors.
Foveon sensors have the SAME luminance moire problems as Bayer CFA sensors.
Foven sensors do not have the same chromatic moire problems as CFA sensors.
Manufacturers who use AA-filters do not do that to prevent chromatic moire problems, but to prevent the false detail to be recorded. That that also prevents chromatic moire effects is a bonus.
Moire patterns are considered very ugly, also from foveon sensors.
Aliasing is considered ugly too.
It is fine to make the choice to not use AA-filters (same as Leica does), but I do not like their bogus marketing speak nonsense,