Nikon D850 - Ten Technical Questions

Started Oct 19, 2017 | Discussions thread
rhlpetrus Forum Pro • Posts: 25,823
Re: Diffraction limit Re: Nikon D850 - Ten Technical Questions

FingerPainter wrote:

Sara Valentine wrote:

FingerPainter wrote:

Sara Valentine wrote:

It is also dependent on the pixel size (i.e. slit aperture).

Pixel size is not a slit aperture, The slit aperture is the lens aperture diameter. Diffraction occurs as light passes through the lens aperture, not as it hits the sensor surface.

The slits are above the photodiode. Things called the color filter array and micro lens array. Those are effectively slits.

I'm willing to accept, for the sake of argument, that those also cause diffraction. However, diffraction from those slits has no impact on image sharpness. Those slits have no effect on which pixel a photon ends up hitting. No matter how much a photon is diffracted by those slits, it still ends up on the same pixel. The diffraction that occurs when light travels through the lens aperture deflects photons to pixels other then the pixels they would have hit if they hadn't been deflected. It is light from a single point on the subject ending up on different pixels that causes any form of blur, including diffraction blur.

Correct, thanks for comment. I never understood where this issue of pixel-dependent diffraction came from, now I see it. Anyway, the relevant diffraction, as you point out, comes from light going through the slit produced by aperture blades, thus the dependence on aperture. Pixel density relates to how much sensor is resolving the effect.

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