Quote Originally Posted by alanrockwood View Post
Actually, the formula is a mathematically rigorous result under the conditions described in my post. It can be derived by a fairly simple derivation involving the moments of a distribution, though I don't recall the details of the derivation at the moment. It even applies to distributions that do not have a finite second moment, such as the Lorentzian function, provided one defines peak width in a slightly different way.
Sorry, but that is too much mathematics for me, even for me who likes theorising about photographic relation. I just can´t follow. Nevertheless it was very useful for me to see that the exponents in the system´s resolution formulae can vary with the conditions you use it for. It seems that for the Perez / Thalmann conditions the squared fractions are more adequate.

Kind regards,
Andreas