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[quote name='PuxaVida' timestamp='1288684930' post='3904']

Hi Wim,



the reference for my statements were:

http://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm and mostly:

http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm



The cornerstone of their statement, which compares the size of the airy disk (diffraction pattern) with pixel size of the sensor came logical to me. Because if the pixel size is smaller than the airy disk, then the diffused photons will be collected by the neighbour pixel, which might alter the real image because of the color recognition concept of the bayer filter. Can this be a problem also for the film?



The amount and cause of diffraction is based on the size of the entrance pupil, that's a fact. But beyond that, I'm trying to understand the effects of diffraction on IQ given that sensors might have different pixel sizes and areas. If you think that this is not the place to discuss this, please send me the links you have so that I can read and learn.



PS: Thanks for the correction regarding the macro comparison.



Kind regards,

[/quote]

You seem to mix things up a bit. Photons do not get diffused, they just end up in other areas of the projected image. Which has no influence on how the projected image gets sampled, and which will not change anything about the captured colours.



For every APS-C 1.5x crop camera, diffraction softening effects on the image will be the same. No matter how high the pixel density is. For every APS-C 1.6x crop camera diffraction softening effects on the image will be the same, no matter how high or low the pixel density is. The same goes for full frame 135 format, whether one uses film or electronic sensors.



The smaller the pixel, the more you zoom in to the image when you look at it at "100% pixel size". This just means you magnify the diffraction softening. But the diffraction is the same as with sensors with lower resolutions.



Airy disks just try to explain the nature of diffracted light, and have less to do with pixels. Circles of confusion do not exist, they merely are a number to try and explain the effect of magnifications to the observer. Magnifications by among other things the sensor size, the print size, the viewing distance.



According to me there is only one thing worthwhile to understand about diffraction: For a given sensor size, diffraction softening at a certain f-value is always the same, no matter what pixel density. And when you compare different sized sensors, equivalent f-values will also give equivalent diffraction softening. So use the crop factor to determine the equivalents.