alundeb wrote:
In my mind, and I don\'t know if that approach makes sense for others, I rate the central sharpness of lenses in classes based the largest aperture they are similar to a lens limited by diffraction only. Each class can theorethically, on a very high pixel density sensor, resolve about 1.4 times more lp/mm than the class below.
I can buy that. However, I believe that any lens resolution tests in the lab are only valuable as a supporting kind of information at best, or they are near useless at worst.
My approach to this is from a practical photography viewpoint. Consider \"image quality\" as a function of several independent variables, one of them is resolution lines/mm, then there is light on the subject, operator skill, camera performance etc. Then we do a little sensitivity analysis by perturbing each of those variables and observing the effect that has on the function \"image quality\". So we describe the function behaviour by the strength of its dependence on each variable.
I think we will find that the \"image quality\" is a very week function of \"lens resolution\" if that variable is perturbed from 400 f/5.6 to say 400 DO. We are also likely to find out that there is a very strong dependence of \"image quality\" on the \"operator skill\" as well as a few other variables. Therefore, when describing the function \"image quality\" behaviour in a real photography setting, we may disregard \"lens resolving power\" variable in the first approximation, as long as the variable doesn\'t change drastically, like going from 400 DO II to an Opteka mirror lens.
What does that all mean ? Well, that means that Ole Bull would have sounded like Ole Bull even when he would have played a $5 violin.
Apr 16, 2015 at 07:39 AM
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