05-20-2011, 04:33 PM
[quote name='Brightcolours' timestamp='1305894242' post='8685']
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.
[/quote]
In the case of bayer sensor, wouldn't the "strength" of AA filter be some two photosites of blur to allow for the sparse "chroma" detectors to work effectively. Foveon would need about one photosite strength. And before you go there, I know you can still extract some RGB info from all photosites, but let's say the "non-native" colour data is limited in value.
I'd consider moire in this case a manifestation of aliasing, so I wouldn't consider that a separate category, but more a subset.
Side note: when I converted the 300D to IR by removing the existing filter assembly, I didn't realise at the time I also removed the AA filter which was in the same module. I thought it looked sharper afterwards. Very rarely do I see something resembling moire or aliasing on it, although the longer wavelengths of IR do cause more diffraction blurring so may offset that itself.
I agree there, but that is the way of marketing.
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.
[/quote]
In the case of bayer sensor, wouldn't the "strength" of AA filter be some two photosites of blur to allow for the sparse "chroma" detectors to work effectively. Foveon would need about one photosite strength. And before you go there, I know you can still extract some RGB info from all photosites, but let's say the "non-native" colour data is limited in value.
Quote: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.
I'd consider moire in this case a manifestation of aliasing, so I wouldn't consider that a separate category, but more a subset.
Side note: when I converted the 300D to IR by removing the existing filter assembly, I didn't realise at the time I also removed the AA filter which was in the same module. I thought it looked sharper afterwards. Very rarely do I see something resembling moire or aliasing on it, although the longer wavelengths of IR do cause more diffraction blurring so may offset that itself.
Quote: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,
I agree there, but that is the way of marketing.
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