Diffraction Limit

Started Aug 28, 2013 | Discussions thread
zodiacfml Contributing Member • Posts: 544
Why make it complicated?!

The OP is correct, diffraction is simply that.  Everything else constant except changing the f number of the lens,  diffraction just limits the information we can capture.

Imagine the aperture of the lens as a filter/hole and photons of light as balls.  For a diffraction limited f-stop, larger photons/balls such as the wavelengths of RED gets filtered and can't get through this hole. So, what gets through that hole is always constant regardless of what catches/absorbs it (such as a sensor format or number of pixels).

If we have a large basket(such as a pixel) but two small green balls can fit in, then we are resolution limited.  If we have very small baskets (small pixels) but one large red ball comes in, the large ball is sliced into pieces to fit in those baskets.  What I'm trying to say here, smaller pixels don't add detail to a diffraction limited capture, it's just over-sampled.

Yet, why do people say that smaller pixels(high res sensors) is bad due in terms of diffraction?  Simple, you just lose efficiency due to diminishing returns.  Efficiency of image file sizes. We still get more detail on higher resolution sensors but for very little gain.

I would like to see a test on this subject since there are two Nikon DSLRs perfect for this, a D3s and a D800.

In matters of DOF and varying sensor formats on diffraction, I think it is a complicated yet futile discussion since we are lens limited anyway, by the smaller formats.

LTZ470 wrote:

From a very credible source:

"Diffraction thus sets a fundamental resolution limit that is independent of the number of megapixels, or the size of the film format. It depends only on the f-number of your lens, and on the wavelength of light being imaged. "

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