Why is contrast good in a lens?

martin s

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Has been bothering me for a while - why would you want a lens to have a lot of contrast? Is there a difference if you add it while printing?

martin
 
Most of my lenses are rather low in contrast (summitar, rigid summicron, summaron, elmar and even a summar) and I just boost the contrast at the printing stage - although I sometimes end up at grade 5 on the Leica enlarger.

I suppose that for colour slide or colour print workers, the contrast issue would be more important. As a purely monochrome photographer, I quite like the fact that with hp5 in ID-11 (or in perceptol for contrasty conditions - eg in India) the highlights are not blown, nor the shadows clogged. All the visual information is there and can be retrieved by judicious dodging and burning during printing.

Best,

Sean in Tipperary (Ireland)
 
With color film you're pretty much stuck with what contrast you get.

In general low contrast lenses on the camera spread the highlights into the shadows. Put a low contrast lens on your enlarger you're spreading the shadows into the brighter areas of the finished print.

There are other trade-offs as well. The first version (8 element) 35mm Summicron seems to be sharper than the later 6 and 7 element versions, but it's a LOT less contrast. The Schneider designed 21mm f/3.4 Super-Angulon has unbelievable central sharpness but lacks the contrast of the later Leica designs.

Some people worry about it, going through their retirement fund chasing the will-o-the-whisp, while other folks learn to work with what they have and they make photographs.

http://thepriceofsilver.blogspot.com
 
Even with a multi-coated single-element lens, the image produced would have a smaller brightness range than that in the subject itself. Therefore, "high contrast" means that this "compression" would be to a smaller degree, compared to a lens with "low contrast" which gives a smaller brightness range in the image comparatively.
 
The advantage is that the lens is also likely to have less flare issues. With monochrome you can get lovely smooth results from modern glass by exposing and developing correctly for your set up. There is no advantage whatsoever in old lenses re highlight preservation unless you are exposing and developing for old glass but shooting new! Adding exposure with a newer lens and reducing development will leave you in the same place, but with less likelihoood of flare issue. The overall look remains different and some people love the older look, but highlight control is not an issue th high contrast lenses as long as you cater to their characteristics. Where people have problems is where you add a Zeiss ZM or Leica asph amongst a line of much older lenses and continue to expose and develop as per the old glass.

I shoot mostly ZM and mamiya 7 glass and hve no trouble with highlights because I give enough exposure and develop modestly. Actually i develop a lot compared to most but thats bec my diffuser enlarger head is very soft. Still, I frequenly find I am printing at G3-4.5.
 
There's a huge difference between gross contrast and microcontrast. You can change gross contrast -- the relation between the lightest and darkest parts of the picture -- quite easily in many ways, but microcontrast -- the resolution of subtle differences in tonality -- requires as much lens contrast as you can muster. Low-contrast lenses may give smooth gradation, but they cannot give subtle gradation.

There will be endless counter arguments from those who confuse smoothness and subtlety, and from those who say, "My Canon f/1.2 [or whatever] is incredibly subtle" but the simple truth is that they're wrong. As has already been pointed out, the subject brightness range is invariably compressed by the lens, so that the image brightness is lower than the subject brightness: this is the 'flare factor'.

A three- or four-glass multicoated lens in a view camera with well blacked bellows may have a flare factor approaching unity, i.e. a subject brightness range of (say) 500:1 is reproduced as an image with a brightness range of almost 500:1, but for most cameras and lenses you're looking at a flare factor of 2 to 4, i.e. 500:1 is imaged at 250:1 or even 125:1. This necessarily involves some loss of information.

Yes, you can restore contrast by extra development, harder printing paper, electronic manipulation, etc., and the results may be very pleasing. But they won't be the same as you'd get with a contrastier lens.

Contrast and resolution are not the same -- you can have high-contrast, low-resolution lenses (uncoated Sonnars, for example) and high-resolution, low-contrast lenses (Xenons and original Summarits, for example) but a high-contrast, high-resolution lens records more information than either. You can throw away part of that information if you don't want it, but you can't re-invent information that was never there in the first place.

Cheers,

Roger
 
Now I kind of understand what you guys are saying, how about controlling contrast while developing. Let's say I develop in Rodinal 1+100, 1+50, 1+25 - is there a difference in developing low contrast and upping it while printing and developing for a lot of contrast right away?

martin
 
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