12-25-2011, 08:44 PM
[quote name='Sammy' timestamp='1324844889' post='14113']
In practice the difference between 4/3 (2x crop) and APS-C sensors (say 1.6x crop) of identical resolution (pixel count) is small. The aperture thresholds at which diffraction starts to limit sharpness are probably less than half a stop apart. The other way around diffraction starts to limit sharpness on a NEX-7 (APS-C) and a 16 MP Panasonic m43 cam at virtually identical aperture settings. Of note, the effect at the aperture threshold is for pixel peepers only - 100% on screen viewing is needed.
[/quote]
On image level, the diffraction softening effects are 2/3rds of a stop "apart" between 4/3rds and APS-C (advantage for APS-C).
Between FF and APS-C 1 1/3rd stop (FF advantage) and between FF and 4/3rds 2 stops (FF advantage).
However, when you look at what matters (aperture size, not f-value) there are no such differences anymore. Just use equivalent apertures and the outcomes will be more or less the same, both for depth of focus and for diffraction related softening.
When you look at pixel level (not very interesting, looking at pixel level...) things are very different. Then it matters what the pixel pitch is, not the sensor size.
In practice the difference between 4/3 (2x crop) and APS-C sensors (say 1.6x crop) of identical resolution (pixel count) is small. The aperture thresholds at which diffraction starts to limit sharpness are probably less than half a stop apart. The other way around diffraction starts to limit sharpness on a NEX-7 (APS-C) and a 16 MP Panasonic m43 cam at virtually identical aperture settings. Of note, the effect at the aperture threshold is for pixel peepers only - 100% on screen viewing is needed.
[/quote]
On image level, the diffraction softening effects are 2/3rds of a stop "apart" between 4/3rds and APS-C (advantage for APS-C).
Between FF and APS-C 1 1/3rd stop (FF advantage) and between FF and 4/3rds 2 stops (FF advantage).
However, when you look at what matters (aperture size, not f-value) there are no such differences anymore. Just use equivalent apertures and the outcomes will be more or less the same, both for depth of focus and for diffraction related softening.
When you look at pixel level (not very interesting, looking at pixel level...) things are very different. Then it matters what the pixel pitch is, not the sensor size.