Lens contrast: how much does it really matter?

Dali · Nov 13, 2012

AgX said:
So far I thought such "Color" designations reflected a better lens-design concerning spectral aberrations. Am I wrong?

By spectral aberration, do you mean chromatic aberration? If it is the case, the lens coating does very little. You can't fix an optical aberration with coating as coating is not supposed to change the lens characteristics but only improve the light transmission and reduce flare which is some cases can improve color fidelity.

Regarding different comments about visible improvement from coating, I also noticed that single coated lenses were good enough at least for the type of pictures I take.

E. von Hoegh · Nov 13, 2012

Lens contrast is very important. You cannot compensate for missing detail in the darkroom, or by increasing development. Single coated lenses can be excellent, multicoating is better but shows it's virtues more in complex lenses such as zooms.

One thing to keep in mind is the value of an efficient lens hood. I use lenses of all ages, from early 1900s to modern multicoated wonders. The hood helps them all. An uncoated Dagor with a compendium hood has better contast than a single coated Symmar without the hood. A multicoated Dagor with compendium has better contrast and more shadow detail than any lens I've ever seen, used, or heard of. My late 60s/early70s Nikkors 35mm lenses have all the contrast I or anyone needs, when used properly.

Veiling flare can be printed through in B&W, but can cause color casts in the shadow areas on color film.
Dirty lenses will show markedly less contrast than clean ones.

So, keep the lens clean, use a hood, and don't obsess over contrast. Any modern coated lens that is clean and in good condition - and modern means post WWII - will give adequate contrast for any purpose if used properly.

Diapositivo · Nov 13, 2012

Any kind of light bouncing around the lens before reaching the film degrades image quality, some detail must be lost. You might like the effect, or not, you might even need it, but the lost "quality" (in the sense of information) is not something that can be recreated in the darkroom.

High internal flare reduces both the contrast of the lens and the "micro-contrast" (acutance) which is one of the qualities that we perceive as sharpness.

That is only of interest to those persons, or circumstances, when you value sharpness of course.

So my answer is that it makes a difference, and that it is a difference that cannot really be compensated in the darkroom. But that said, using a low-contrast (high-flare) lens and raising contrast in the darkroom can give you the results you were looking for.

Brian C. Miller · Nov 13, 2012

RalphLambrecht said:
Contrast is controlled through film development and printing and the taking lens and lighting conditions

As an example, let's say that you are outdoors. Your camera has a Busch Rapid Aplanat lens, circa 1904.

What would you do with the lens to control scene contrast? Say on a sunny day, or a cloudy day.

ntenny · Nov 13, 2012

Brian C. Miller said:
As an example, let's say that you are outdoors. Your camera has a Busch Rapid Aplanat lens, circa 1904.

What would you do with the lens to control scene contrast? Say on a sunny day, or a cloudy day.

Replace it with a different one. I'm not sure I understand the intent of the question---we all agree that a lower-contrast lens is going to lose information, in the form of microcontrast distinctions, that can't then be "resurrected" in the darkroom, don't we?

-NT

E. von Hoegh · Nov 13, 2012

Brian C. Miller said:
As an example, let's say that you are outdoors. Your camera has a Busch Rapid Aplanat lens, circa 1904.

What would you do with the lens to control scene contrast? Say on a sunny day, or a cloudy day.

As uncoated lenses go, that one will have extremely good contrast as it has only 4 air-to-glass surfaces. I'd use a compendium shade, sunny or cloudy and not worry, it will give excellent contrast.

cliveh · Nov 13, 2012

The lens is not the only thing that controls contrast, but I can't imagine ever buying a Leica Summar lens.

Brian C. Miller · Nov 13, 2012

ntenny and E. von Hoegh, thanks, what I'm wondering, is based on Ralph's post, how is a lens used to control contrast? Lets say you have just one lens, either "antique" or "modern." What would be done with the lens to control contrast? And I don't mean swap out, I mean lens technique.

BTW, Nathan, I agree with E., the lens is really good. Mine is a No. 4 13", which I use on 8x10. That lens has no problem giving a lovely image on color or B&W. And yes, I use a compendium shade. Makes a view camera look like it has a real purpose!

E. von Hoegh · Nov 13, 2012

Brian C. Miller said:
ntenny and E. von Hoegh, thanks, what I'm wondering, is based on Ralph's post, how is a lens used to control contrast? Lets say you have just one lens, either "antique" or "modern." What would be done with the lens to control contrast? And I don't mean swap out, I mean lens technique.

BTW, Nathan, I agree with E., the lens is really good. Mine is a No. 4 13", which I use on 8x10. That lens has no problem giving a lovely image on color or B&W. And yes, I use a compendium shade. Makes a view camera look like it has a real purpose!

Well, beyond using a proper shade, making certain the glass is clean, and giving the correct exposure for the scene there isn't anything else you can do with the lens.

BTW, that lens on 4x5 will give you incredibly sharp (corner to corner) negatives. Show one to someone who just shelled out $$$$ for a brandy-new Apo-Something.

Diapositivo · Nov 13, 2012

Brian C. Miller said:
As an example, let's say that you are outdoors. Your camera has a Busch Rapid Aplanat lens, circa 1904.

What would you do with the lens to control scene contrast? Say on a sunny day, or a cloudy day.

Close the aperture? (I suppose flare is bigger a problem with bigger apertures, as the peripheral part of the lens contributes more to the image).
Remove the "protection UV filter" if one is present. They do add flare, in dire conditions especially.
If you work with a tripod, project a shade on the lens with your hand (or whatever) in such a way that the hand is not in the picture but the shade falls on the lens.

ntenny · Nov 13, 2012

I think whoever originally said that contrast was "controlled" with the lens meant that it was affected by the characteristics of the lens, not that there are ways to change it by adjusting the lens. Hence my "replace it with a different one", which may have sounded like I meant something was wrong with the Busch lens---but if I wanted to change the contrast of the resulting negative, and I was limited to using the lens to do that, I'd do it by going and getting a lens with different contrast.

(Though I guess the couple of posts above, pointing out that flare affects contrast and so shades and aperture choice have effects, are right too.)

-NT

Klainmeister · Nov 13, 2012

I do know this: with BW I find the difference to be not quite as apparent (adjust development, printing, etc) but with chromes I hugely can see a difference. One has a punch and the other looks dull, and when it's all said and done, I could compare the same scene with same conditions and film and clearly tell which one had better glass/coatings in relation to contrast. A side effect of a higher contrast lens is apparent sharpness too. Whether or not it's actually sharper isn't the issue, but the perceived sharpness because of the high contrast lens will definitely stand out.

EDIT: this is comparing two sets

First being the difference in chromes with a Minolta Hi-matic and my Pentax 50mm 1.4 -- clear and bright with the Pentax, much more subdued with the Minolta.

Second being when I went from a Fuji GW690 to my Mamiya 7II. Side by side on a light table, one doesn't take much observing to pick out which is which.

RalphLambrecht · Nov 13, 2012

Brian C. Miller said:
what I'm wondering, is based on Ralph's post, how is a lens used to control contrast? Lets say you have just one lens, either "antique" or "modern." What would be done with the lens to control contrast? And I don't mean swap out, I mean lens technique.

depending on the lens, different apertures,f/stops may give different image contrast, but beyond that, there is very little contrast control with any given lens, i'm afraid. tne other question is:how do you want to measure and quantify lens contrast? how else would you compare lenses and their settings?

Poisson Du Jour · Nov 13, 2012

Statements such as "contrasty lens" bandied around in forums (and dealers!) continually irk me. In years and years of printing to exhibition/gallery standard (Ilfochrome) using very high quality optics, I have not given much credit at all to a "contrasty lens", certainly not letting it sway judgement. If I end up with a lens that is "contrasty", you can bet your nellie the lens was considered for a very wide variety of factors, and that (contrast) wasn't one of them. Come to think of it now through reference, all of my Pentax 67 lenses are described as "sharp and contrasty". So? So...well, the images are very beautiful framed under spots (so are everybody else's MF prints), but there is more to it than "contrast" properties of a lens. Besides all of that, how is a lens judged or ascribed as "contrasty"? What is the quantification and qualification?

E. von Hoegh · Nov 13, 2012

Poisson Du Jour said:
Statements such as "contrasty lens" bandied around in forums (and dealers!) continually irk me. In years and years of printing to exhibition/gallery standard (Ilfochrome) using very high quality optics, I have not given much credit at all to a "contrasty lens", certainly not letting it sway judgement. If I end up with a lens that is "contrasty", you can bet your nellie the lens was considered for a very wide variety of factors, and that (contrast) wasn't one of them. Come to think of it now through reference, all of my Pentax 67 lenses are described as "sharp and contrasty". So? So...well, the images are very beautiful framed under spots (so are everybody else's MF prints), but there is more to it than "contrast" properties of a lens. Besides all of that, how is a lens judged or ascribed as "contrasty"? What is the quantification and qualification?

No veiling flare and good separation of tones in shadows and highlights.

edit - If you are using "sharpness" as a criterion, you are considering contrast whether you know it or not. Sharpness and contrast are inextricably linked.

Poisson Du Jour · Nov 13, 2012

E. von Hoegh said:
No veiling flare and good separation of tones in shadows and highlights.

edit - If you are using "sharpness" as a criterion, you are considering contrast whether you know it or not. Sharpness and contrast are inextricably linked.

OK. I recall when I got the Pentax 67 lens that my only criterion was to "get some decent lenses" (I was a bit more specific starting out with the Canon kit many moons ago). Of course now I realise I got much, much more than I bargained for (I almost came home with a Hasselblad kit...) and I'm not complaining, certainly not about sharpness. It's good to have this contrasty lens subject out in the open, as too often a "contrasty lens" is judged as the only one somebody should buy without due and careful consideration to other factors (weight, ease of use, prime vs zoom, others...).

E. von Hoegh · Nov 13, 2012

Poisson Du Jour said:
OK. I recall when I got the Pentax 67 lens that my only criterion was to "get some decent lenses" (I was a bit more specific starting out with the Canon kit many moons ago). Of course now I realise I got much, much more than I bargained for (I almost came home with a Hasselblad kit...) and I'm not complaining, certainly not about sharpness. It's good to have this contrasty lens subject out in the open, as too often a "contrasty lens" is judged as the only one somebody should buy without due and careful consideration to other factors (weight, ease of use, prime vs zoom, others...).

Actually as long as you're talking about post WWII (coated) lenses, good contrast is more or less a given. Give a ca. 1950 135mm Graflex Optar (A Tessar type, renamed single coated Wollensak Raptar) a try, they're superb.

Ian Grant · Nov 13, 2012

cliveh said:
The lens is not the only thing that controls contrast, but I can't imagine ever buying a Leica Summar lens.

Here you open another can of worms.

An issue with some German lenses in the 1930's was the new optical glasses introduced, Leitz used them for the Summar, Zeiss for some redesigned Tessars and it went into some Novars. This glass ages badly whether it's atmospheric exposure to something I don't know but the result over the past few years is that some of these lenses have a distinct softness and despite the glass being clean & scratch free there's a very slight haziness which has a profound effect on contrast. The worst I've seen is on a Zeiss Ikonta with a Novar but I've seen it with a few Tessars and it's known in Summars. The new glasses were introduced to facilitate the production of faster lenses but they are significantly softer so more prone to issues like scratching during cleaning.

There's probably other lenses affected but those are the 3 I've seen first hand, glasses changed again towards the end of the 1930's. The 135mm and 150mm Tessars were redesigned to fit the rimset Compur shutters around 1929/30 and again by 1938 when a more modern version of the f4.5 150mm appeared with T coating.

So back to the Summar, many are soft, a great many are ruined with cleaning marks because the glass is so soft, but there are some that are OK. My first Summar came with a Leica IIA but I knew the lens was poor, that was 40 years ago. I replaced it with an Elmar. However knowing the issues with Summars I didn't buy another until I spotted a good one.

The secret to checking is the reflections in a lens, you need good sharp reflections, no haze or diffusion particularly when that reflection itself is passing through other air glass surfaces.

I've 4 CZJ Tessars (150mm & 165mm) sat in front of me 1913, 1926, 1932 and 1952/4, the worst is the 1930's version and I've had 3 that age before quite similar. My experience is the contrast difference between the earlier Tessars and the T coated Tessars is much closer than the 30's versions. Have to be careful here as not all Tessar FL's were reformulated with the new glass in the early 30's.

Ian

cliveh · Nov 13, 2012

Thanks for that, as you mentioned many aspects I was nat aware of.

Brian C. Miller · Nov 13, 2012

RalphLambrecht said:
tne other question is:how do you want to measure and quantify lens contrast? how else would you compare lenses and their settings?

A lens measurement would have to be conducted in a controlled environment with a test chart, and I'm sure that it would be similar to MTF testing ("evaluates a lens' performance, and its contrast sensitivity"). There are a number of free test charts available, and I would personally use a test target in a box like I saw one someone's web page. The photographer pointed the camera into the sun, and photographed the test target inside of a box. He did it with and without a lens hood.

On the LFPF, we had a discussion about "bokeh," and I facetiously came up with the Drem Glasgnademeter and Leica Glasgeistometer. Later I came up with a set of possible measurements. I suppose things like flare and contrast control could be valid parts of that measurement.

Klainmeister · Nov 13, 2012

Neither linky is worky... =[

Ian Grant · Nov 13, 2012

E. von Hoegh said:
Actually as long as you're talking about post WWII (coated) lenses, good contrast is more or less a given. Give a ca. 1950 135mm Graflex Optar (A Tessar type, renamed single coated Wollensak Raptar) a try, they're superb.

We are in the 35mm sub forum but what's being said is still valid, and thats from experience.

However there are exceptions like the Hoya lenses. I had a 28mm and flare was horrific, I had a Sigma 24mm before that and it wasn't much better.

On the oyher hand LF lenses were always professional so coatings of all types were a league ahead.

Ian

E. von Hoegh · Nov 14, 2012

Ian Grant said:
We are in the 35mm sub forum but what's being said is still valid, and thats from experience.

However there are exceptions like the Hoya lenses. I had a 28mm and flare was horrific, I had a Sigma 24mm before that and it wasn't much better.

On the oyher hand LF lenses were always professional so coatings of all types were a league ahead.

Ian

Ian, what about the Hoya HMC filters? I have one 72mm (the only HMC I have) that's very good, I use it as a protective filter on a 20mm WA lens, as far as flare and reflections go it might as well not be there. Are they all this good or should I watch out?

Ian Grant · Nov 14, 2012

E. von Hoegh said:
Ian, what about the Hoya HMC filters? I have one 72mm (the only HMC I have) that's very good, I use it as a protective filter on a 20mm WA lens, as far as flare and reflections go it might as well not be there. Are they all this good or should I watch out?

Hoya's Multo Coating is usually vey good, the lens problem was a mistake in the design/production probably to cut costs it wasn't faulty coating rather they just didn't coat every air/glass interface. There's no problems with Hoya's top Tokinna range of lenses. Hoya used to hide the links between the two companies for some obscure reasons now the link is acknowledged openly.

Coatings have improved further over the years since Multicoating became common with the advent of SMC Takumar lenses, it was pioneered by Zeiss in West Germany and put into production by Pentax. I've never had an issue with Hoya lenses and I've been using them for about 38 years.

Ian

Brian C. Miller · Nov 14, 2012

Klainmeister said:
Neither linky is worky... =[

Hmmm, they work for me, so I'm guessing that it's because it automatically logs me in to the forum.

Brian C. Miller said:
See? You guys need to use a Drem Glasgnademeter to measure bokeh. That little Nikon meter just gets pegged when the LF lenses are placed on it. Plus, you need real statistics and measurements about that lens, not a one-size-fits-all number. The Leica Glasgeistometer used crystal prisms to obtain mean, standard deviation, radii, and the later versions could obtain inferential statistics as well. Unfortunately, most of these have been dismantled by new-age hippies to be used as necklaces and earrings.

Brian C. Miller said:
Things which make up a lens' grace:
1. Halo
2. Blur
3. Blur point distortion (even, centered, ring)
4. Formation
5. Edge distortion

Halo would be the amount that a reflected white object would intrude into an adjacent black object.
Blur would be the amount of defocus blur, based on distance from the focus plane, and also per aperture.
Blur point distortion would be the amount of distortion of a blurred point object, measured for eveness. 0 would be neutral, negative would be a ring, and positive would be a "hot" point. This may need to be expressed with deviation.
Formation would be blur point forms, such as the hovering dots from strainer-type discs or aperture leaf patterns.
Edge distortion would be what happens at the edge of the lens coverage, including "swirlies" compression and notable drop in resolution and coverage.

Lens contrast: how much does it really matter?

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