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04-27-2010, 10:48 AM   #1
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Contrast Vs Sharpness

Just a random rambling thought.

I've done the slight upgrade from the 18-55 to the 16-45 and although the sharpness seems a bit better with the 16-45 the contrast difference seems to be more obvious between the two. And in some ways I think that contrast is more important in my impression of initial image quality when I'm not pixel peeping. And doesn't good contrast give the impression of better sharpness?

04-27-2010, 10:51 AM   #2
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QuoteOriginally posted by VaughnA Quote
Just a random rambling thought.

I've done the slight upgrade from the 18-55 to the 16-45 and although the sharpness seems a bit better with the 16-45 the contrast difference seems to be more obvious between the two. And in some ways I think that contrast is more important in my impression of initial image quality when I'm not pixel peeping. And doesn't good contrast give the impression of better sharpness?
It is all relative. There is no "best" setting for every shot.
04-27-2010, 10:53 AM   #3
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Yup, true.
Most DA series lenses offer almost ridicoulous contrast. But while contrast makes pictures more lively and gives them more depth you can add missing contrast in post processing while you can't add sharpness.
So I'd rather have a lens that is very "sharp" but only has mediocre contrast instead of the other way round.
However I'm sure the 16-45 is better in every aspect (except maybe close focusing).
04-27-2010, 11:36 AM   #4
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I have both a 18-55 DA II and a DA* 16-50, and while the DA* is supposed to beat the kit lens in terms of sharpness, your post reminds me that some day I'd like to test them side by side.

I'm curious to see if Adobe's Camera Raw "clarity" setting (midtone contrast) impacts the look from lens to lens, or if that more a function of a particular scene's inherent tones.

04-27-2010, 12:01 PM   #5
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QuoteOriginally posted by VaughnA Quote
Just a random rambling thought.

I've done the slight upgrade from the 18-55 to the 16-45 and although the sharpness seems a bit better with the 16-45 the contrast difference seems to be more obvious between the two. And in some ways I think that contrast is more important in my impression of initial image quality when I'm not pixel peeping. And doesn't good contrast give the impression of better sharpness?
"Sharpness" is to a large degree defined by contrast! The proper name would be "accutance".

Sharpness as such is not a measure, but a product of resolution and contrast, as for instance given by the MTF. And sharpness is a perceptive quantity. So, it is no surprise, that contrast seems to be the dominant definig factor for sharpness. In fact, if you do a search on the web, you'll probably sooner or later find discussions about lens quality, where often the lens with the higher contrast outperforms a lens with a higher resolution.

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04-27-2010, 12:19 PM   #6
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In the case of the 16-45, the contrast is arranged so as to create an impression of more sharpness than is there. Comparing to e.g. the 43, at first glance I thought the 16-45 was much contrastier, but the 34 had a wider latitude, and in fact turns out to be sharper - in terms of resolution and contrast.
04-27-2010, 01:04 PM   #7
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QuoteOriginally posted by Ben_Edict Quote
Sharpness as such is not a measure, but a product of resolution and contrast, as for instance given by the MTF.
Zeiss has some good articles on MTF here and here.

I sometimes wonder whether people say contrast when they really are impressed by the saturation of contrasting colors. I am also wondering if "micro-contrast" is the term used to refer to the contrast component of sharpness.

Last edited by Laurentiu Cristofor; 04-27-2010 at 01:18 PM. Reason: Fixed link to direct to article, rather than CNL issue
04-27-2010, 01:57 PM   #8
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QuoteOriginally posted by Laurentiu Cristofor Quote
Zeiss has some good articles on MTF here and here.

I sometimes wonder whether people say contrast when they really are impressed by the saturation of contrasting colors. I am also wondering if "micro-contrast" is the term used to refer to the contrast component of sharpness.
There are several contrasts:
brightness contrast (that's what typically shows up in MTF curves, as the measurement targets are mostly simple black print on white),
colour contrast, which as you wrote, will certainly influence the perception of sharpness, but is (at least not to my knowledge) not taken into account for MTF
*and several more composition related contrasts (forms, quantitity )

I would agree, that standard MTF measuerements would be based on what is called "micro-contrast". The question is, how that relates to the final image!

There is a nice, though not exactly scientific, essay on Luminous Landscapes: Understanding Lens Contrast

Ben

04-27-2010, 06:58 PM   #9
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QuoteOriginally posted by Ben_Edict Quote
colour contrast, which as you wrote, will certainly influence the perception of sharpness, but is (at least not to my knowledge) not taken into account for MTF
I think so too, but I only made it through the introduction to an article on MTF, so I could have missed lots of things I thought it was the first Zeiss article, but now that I looked through it again, I must have read a different one.

QuoteOriginally posted by Ben_Edict Quote
I would agree, that standard MTF measuerements would be based on what is called "micro-contrast". The question is, how that relates to the final image!
Less need for sharpening I'd imagine. Although, because we usually share scaled down images, sharpening is still necessary.

QuoteOriginally posted by Ben_Edict Quote
There is a nice, though not exactly scientific, essay on Luminous Landscapes: Understanding Lens Contrast
Thanks for that link. I've seen "micro-contrast" being mentioned here and there, but I didn't see an actual definition of what people meant by that term. After reading about MTF, I imagined it referred to the "contrast" measured there, but your linked article is the first time I see these being put together.
04-28-2010, 02:55 AM   #10
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QuoteOriginally posted by VaughnA Quote
Just a random rambling thought.

I've done the slight upgrade from the 18-55 to the 16-45 and although the sharpness seems a bit better with the 16-45 the contrast difference seems to be more obvious between the two. And in some ways I think that contrast is more important in my impression of initial image quality when I'm not pixel peeping. And doesn't good contrast give the impression of better sharpness?
I am in complete agreement with you. Only at 100% the sharpness plyys a bigger role, at all others micro contrast seems to render an image sharper.
04-28-2010, 02:58 AM   #11
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I think, the LL eassy makes the definition of micro-contrast quite clear: it is the small-scale contrast, which we also typically can define as edge contrast (and that is at the end of the day, what is measured in MTF). Edge contrast is also what is enhanced when you apply an unshrap mask for sharpening.

Macro-contrast, on the other hand, is the overall contrast a lens delivers over the whole image area. Macro-contrast is largely dependent on things like coating or flare-resistance (or lack off). This is, what we generally perceive as being THE contrast of an image, whereas micro-contrast will be perceived as "sharpness" or accutance.

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04-28-2010, 06:59 AM   #12
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Thanks for the replies, I'm going to read the Ziess documents when I get home tonight. What I'm hearing here seems to correspond with what I'm seeing.
04-28-2010, 08:09 AM   #13
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Perhaps macro-contrast is somewhat analogous to USM with a large radius and small %, while micro-contrast is USM with a tiny radius and high %.
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