Sensor size and diffraction.

ProfHankD wrote:

Tom Axford wrote:

BobORama wrote:

Erik Ohlson wrote:

Cute cartoon, but you are obviously not considering the SMALL sensor, diffraction-limited cameras under discussion.

Your f/3.3 rule is bunk as it does not take into account the size of the sensels, which is about the only thing you don't mention, and the only thing that matters other than f-stop.

Your rather blunt response suggests that you are one of the small minority who believe that depth of field should be defined in terms of the number of pixels in the image rather than just the overall size of the image in the camera (i.e. the sensor size).

If the conventional definition of depth of field is accepted, then Erik is entirely correct. By conventional definition, I mean that used for the past hundred years; e.g. the definition used when depth of field scales are engraved on manual focus lenses and also the definition used by popular online DoF calculators.

If you wish to start yet another argument about the "correct" way to define depth of field, it might be better done by starting a new thread on that topic.

No, Bob's right: you need a well-specified resolution reference to give a CoC (circle of confusion), and that can be taken either by pixel dimensions or by approximating human visual acuity for a specific print size and viewing distance.

Well, you seem to want to re-open that argument. I'm not biting, I stick by what I said. We have been through it all before!