Depth of field, size of pixels, and diffraction

Birch burr, originally uploaded by jiihaa.

It is interesting how sometimes many things come together, such as photography, digital cameras, quantum mechanics, and optical diffraction. I was first directed by Eolake to an essay on diffraction by Ctein (excellent commentary!).

From there I went to read a discussion about maximum depth of field with different sensors. And finally, I was pointed to a tutorial about diffraction, where there is an interactive tool to explore the effects of various apertures and pixel sizes.

All this information is available on the net, all this is relevant, all this is first-class information. It is interesting to see that photography has a practical connection to modern physics. But photographers don't of course need to be physicists to make good photos.

It is great how different kinds of experts come together and constructively discuss a joint interest - what are the technical limits on sensor sizes, and how this affects photography. In fact, these discussions pretty much demolish the need for more pixels in cameras. Or at least, photographers should know what is the effect of decreasing the aperture on image quality.

On my LX3, diffraction starts to eat the image quality probably at f/2.8 (perhaps already at f/2.0), and on compact cameras with more megapixels and smaller sensors this starts even sooner. Coming back to Ctein, what you are seeing in the pixel-level in these megapixel monsters is some quantum weirdness...

Update: I forgot to link to LX3 Sensor Analysis by Emil Martinec at the Dpreview forums. It seems that the sensor is really impressive, much better that in the G10 as a comparison. But this is quite involved physics, so beware.

Update 2: I forgot to note why I selected this particular photo here - it brings to mind the overlapping Airy disks.