End of Megapixel wars and EF-S buying decisions

Started Feb 23, 2006 | Discussions thread
U Sererra Regular Member • Posts: 317
Re: Doesn't really work that way.

Peter G wrote:

Depth of field is depdant on the phisical captur area of the
sensor. Ie 22 x 15mm

Diffraction OTOH is limited by the size of the individual pixels.
As you cram in more pixels you get closer to diffraction limit, but
you don't get get more DOF.

Yes, I forgot to say, 'when comparing sensors with the same resolution'.

With a smaller sensor, you hit a given DOF at a larger aperture, and because the pixel size is smaller, this larger aperture is the point at which diffraction starts to become an effect at the given pixel size.

For a larger sensor, you hit same DOF at smaller aperture, at which point diffraction is a bigger problem, but because your resolution is the same, pixels are larger, and so it evens out. This is I think true in the theoretical world anyway.

Worse yet, you may reach a point that diffraction limits the sensor
before you hit the pure optical sweet spot of the lens.

Now, does lens sweetspot aperture change depending on the size of image circle you need to project - i.e: could lenses built for smaller sensor have sweetspot at a smaller f-stop value, overcoming this problem you mention above?

So much speculation on my part. Could be talking rubbish.

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