Riccardo Correani wrote: > A well regarded italian magazine published a special issue > detailing MTF tests of many Nikon lenses. These tests cover many > technical aspects of a lens performance. > Sharpness is plotted on a graph having the sharpness factor on the > Y axis (centre of frame, edge and average) in a 1-10 scale > where 10 is maximum, against f-stops on the X axis. Just a word of warning - MTF describe the contrast of black and white bars with a sinusoidal intensity profile incoherently imaged by a lens. Magazines usually publish information from lens MTF tests which is insufficient to be useful, for example spot values which are given names like "sharpness" or "resolution". To be of any use it is essential that these terms are defined in the context of the test (not in their generic meaning). Even then, to be quite honest, their is little use in giving spot values. Giving spot values is a bit like giving spot amplitude (i.e. no phase information) frequency response and cut off values for Hi-Fi amplifiers/speakers.
