Olympus 17/1.8 review

Started Nov 17, 2012 | Discussions thread
noirdesir
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Re: Macrocontrast vs. Microcontrast
In reply to Anders W, Nov 18, 2012

Anders W wrote:

noirdesir wrote:

Anders W wrote:

It is certainly true that the usage of the term "microcontrast" is not well defined. However, it is obvious to me that it must originally have been coined in contradistinction to global contrast or macrocontrast, and thus refers to contrast at frequencies (resolution criteria) some distance away from zero. At the same time, I have the impression that at least some people use it in reference to contrast at fairly low frequencies rather than very high ones, lower frequencies arguably being more important for perceived image quality at ordinary display size.

It is my impression that it has been coined both in contrast (no pun intended) to global contrast AND to resolution. If we take MTF50 as resolution, this would mean the contrast somewhere between 0 and the 50% mark but some people (like DxO or DPreview with their extinction resolution) consider a much lower contrast for their 'resolution' definition.

Didn't you mean to say somewhere between the 100% and the 50% mark here rather than between 0 and 50%? If yes, then I am all with you.

I think there might be different definitions of microcontrast, as you said that "at least some people use it in reference to contrast at fairly low frequencies rather than very high ones", thus it could be contrast at resolutions between the 0 and 50% mark (but closer to the 50% mark) or it could be the contrast a bit above that.

One further question: Would you agree with my assessment that, as far as Ming's images let us judge, the 20 has a better MTF curve than the new 17/1.8? I must admit, I am a bit disappointed at the showing of the 17/1.8 here. I hadn't really expected it to beat the 20 in this regard but I had hoped/expected that it would do about as well. If that had been the case, I would probably have been ready to exchange my 20 for the 17/1.8. Now, I am not so sure.

I'm not sure, my general impression from his review is that the two lenses are relatively close (with a few notable differences like LoCA and vignetting that favour the 17 mm), and closer than I though they would be. But evaluating MTF from a few crops is something I am not really comfortable with, I'd put more weight on his overall comments which I would assume to be based on a lot more (test) images than the ones shown.

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