Olympus 17/1.8 review

Ming,

A few years back I tried to figure out a definition for the term microcontrast. Since the most comprehensive way to measure contrast of a lens is a full MTF curve, lenses with different amount of microcontrast should have characteristically different MTF curves. To this day, I keep being surprised that I have not seen a single person talk about this (how microcontrast is reflected in a MTF curve).

I showed a generic example of two lenses with very different character in this post:

http://forums.dpreview.com/forums/post/35584548

and discussed it further in this post:

http://forums.dpreview.com/forums/post/37010026

Of note is that all full MTF curves that I have seen, eg, from DxOmark, always start at one, ie, 100% contrast. That is obviously not really correct as every lens + camera system has some internal flare. While one naturally can normalise all MTF curve to one, this would clearly paint 'foggy' lenses in a much better light than it should be. My idea of what you mean with macrocontrast would be the contrast at essentially target resolution of zero, whereas microcontrast would be the contrast at finer resolutions, whether that is the contrast below the resolution of the MTF50 value as I insinuated in the first post I linked to above or the contrast just above that resolution, I don't know.

And since nobody has rigorously defined microcontrast to my knowledge yet, so far I can only answer that by comparing lots of full MTF curves of lenses which are claimed to either have good or bad microcontrast to see whether there is a pattern (or whether the term microcontrast either covers a wide array of lens behaviours or is just not used very consistently).