Lens contrast vs digital contrast

[Redseele]

I apologize, I'm starting so many threads and questions these days... bare with me, I'm just a very curious person in matters to our beloved hobby.

I'm contemplating the issue of contrast in lenses. I'm torn between buying a lens with beautiful rendition but low contrast (a Summicron Rigid) vs few with more contrast but a rendition that's different (Summicron Type 3, Voigtlander Nokton 1.5, etc.). The main question then: is there any difference between the natural contrast of a lens and just upping up the contrast in Lightroom?

A bit of background: I shoot mainly film but also digital. I print my black and white pictures and I can control contrast very easily with graded paper. Color I always digitize and then print, therefore I can control the contrast with Lightroom. Is that contrast between a contrasty lens and one enhanced by Lightroom similar?

Thank you for helping out with my mad curiosity 🙂

 

[mfogiel]

There are two types of lens contrast: micro contrast and macro contrast. You can undesrtand this better by reading this:
http://www.zeiss.com/content/dam/Photography/new/pdf/en/cln_archiv/cln30_en_web_special_mtf_01.pdf
http://www.zeiss.com/content/dam/Photography/new/pdf/en/cln_archiv/cln31_en_web_special_mtf_02.pdf
In practice, it is quite easy to increase or decrease the macro contrast digitally, but almost impossible to ADD micro contrast, where there isn't.
You also need to consider, if B&W or colour are your main game. In colour the contrast is helpful to obtain "cleaner" hues, so lenses with more contrast are producing images that are easier to work with, in B&W it is all about the subtle gradations of grey, and low contrast lenses are usually preferred ( as long as they don't flare too much). Top B&W Leica lenses are 35/2.8 Summaron, 35/2 Summicron 1st, 50 mm Summicron Collapsible, rigid, DR, and the 50/2.8 Elmars both old, and particularly the new one - a bit more contrasty but also a great deal sharper and more flare resistant.

DR Summicron

2008050307 by marek fogiel, on Flickr

 

[Perks]

Good question, and answer.

 

[ferider]

Talking about macro-contrast only:

1) Any lens will only reduce contrast of a scene, modern lenses with better coatings less so than older lenses.
2) The eye can see > 17 "bit" (or "stops") dynamic range, film and digital have anywhere between 12 and 14 bits/stops; so the contrast question is about how to map/cut/stretch/compress the 17 bits that the eye sees to the 12-14 bits that the camera can record. Some films with careful development can go higher, but in the end everything has to be mapped to 8 bits/stops if you want to show on the web or print digitally.
3) Older lenses reduce contrast in the low-lights due to veiling flare. The more elements and glass to air surfaces, the more so. The rigid Summicron was a stretch for its time with 7 elements and 11 glass/air surfaces. A Sonnar from the same period, for instance, has less veiling flare.
4) On negative film, you can reduce/increase contrast via exposure and development. It's very difficult to blow highlights, so you typically expose for shadows. Contrary to normal wisdom, I feel you can achieve almost any contrast effect you want, also with the most modern / highest contrast lens, you just have to expose correctly.
5) On digital and slide film highlights are easily blown. You expose for the highlights, typically, and on digital, you can manipulate the shadows in post as much as the dynamic range of your camera allows.

On the other hand, resolution on digital is what it is. You cann't fix lack of lens resolution in post.

This is why I love to use lower contrast / higher resolution lenses on my 240. It's easier to pull the shadows, and I like the mellow colors that they give, the rigid Summicron in particular.

BTW, have no fear, the Summicron v3 (like all Mandler lenses) is quite gentle on the shadows, too.

Roland.

 

[Redseele]

That's a lot of useful information and it explains why some early summicrons and summarons are so good for black and white: micro-contrast! Zeiss lenses also have a lot of this.

But my question was a bit different. Basically, for instance, could you make pictures taken with a low contrast lens look like one with a higher contrast lens by using the contrast slider in Lightroom? Could you make a, say, make pictures taken with a Summicron Rigid look like that of a version 3 or 4 Summicron in terms of contrast?

 

[ferider]

But my question was a bit different. Basically, for instance, could you make pictures taken with a low contrast lens look like one with a higher contrast lens by using the contrast slider in Lightroom? Could you make a, say, make pictures taken with a Summicron Rigid look like that of a version 3 or 4 Summicron in terms of contrast?

Basically yes, for most pictures.

Note, however, that strong flare and ghosts in particular are impossible to fix.

 

[willie_901]

There is a difference.

The lens affects/controls/determines the information content recorded by the sensor assembly. If the exposure (shutter time/aperture) is sufficient, the lens properties are retained. As the analog signal-to-noise ratio decreases (under exposure) so does the information content. No lens can save one from information loss due to underexposure when the shutter is open.

Nothing beats original data. Even the most clever rendering algorithms can not create information that was never recorded. However rendering algorithms can accentuate (or attenuate) whatever contrast is present in the original data. Information can be destroyed, so unlike creating contrast that was never there, decreasing rendering contrast is limitless.

With regard to lenses, the Zeiss ZM 50/1.5 C-Sonar lens behaves as a low-contrast lens below ~ f 4 and a high contrast lens at narrower apertures. No doubt there are other lenses with dual personalities as well.

 

[ferider]

With regard to lenses, the Zeiss ZM 50/1.5 C-Sonar lens behaves as a low-contrast lens below ~ f 4 and a high contrast lens at narrower apertures. No doubt there are other lenses with dual personalities as well.

True. I just got one, the Nokton 50/1.1.

 

[Redseele]

Just out of curiosity (and I mean no offense to anyone's preferences), is there any Voigtlander lens that has good micro-contrast? I used to love my Nokton 40mm until I tried using it with Tri-x and noticed the tones were very muddy. The same happened when I had a 28mm Ultron.

 

[ferider]

Just out of curiosity (and I mean no offense to anyone's preferences), is there any Voigtlander lens that has good micro-contrast? I used to love my Nokton 40mm until I tried using it with Tri-x and noticed the tones were very muddy. The same happened when I had a 28mm Ultron.

Which Ultron, RS ? My 28/2 is pretty good, but the 28/1.9 "muddier" just as you said.

When I read your question, the lenses that came to mind immediately are the color skopars (28/3.5 in particular).

The new VM Nokton 50/1.5 is not bad either.

Roland.

 

[Redseele]

The 28mm Ultron f2 is the one I was referring to. You may be right, I just checked some of my own tri-x negatives and the lens wasn't as bad as the 40mm Nokton. I remembered that I really liked that lens for color. Unfortunately when I got into digital leicas I noticed it had focus shifts like crazy.

 

[willie_901]

True. I just got one, the Nokton 50/1.1.

Congratulations!

 

[Hsg]

Is that contrast between a contrasty lens and one enhanced by Lightroom similar?

From a digital perspective, an ideal RAW file has a histogram like this:

An image with such a histogram looks very low contrast; however, it does not look soft, which means unsharp. The lens resolution is apparent even in such a low contrast image.

So, an ideal lens for digital has very high resolution and low contrast.

Resolution cannot be adjusted later on, even the best sharpening method does not replace lens resolution... Not to mention a lens for digital must be able to resolve the sensor resolution.

That was the digital point of view - buy the highest resolution lens and the rest, even distortion can be fixed later on.



As far as film is concerned. B&W film and digital live or die by the right contrast. Personally, I give up on b&w because I was sick of the contrast problem.

 

[willie_901]

From a digital perspective, an ideal RAW file has a histogram like this:

...

This post brings up an important point. The histogram is ideal because all of the analog signal (light) was properly measured by the camera's data stream.

The data stream has a linear response. This means all of the information required to accurately render an image is present. During post-production (which could be in-camera for connivence), the information can be extracted to produce the desired aesthetic result. Non-linear functions modify the original linear data.

The shape, or distribution, of the histogram is another issue altogether.

The light itself can be from a high-contrast scene (bright sun at noon on a beach) or low contrast scene (a gray card).

Lenses filter the signal (light). Here the word filter just means the properties of the light entering the lens are different than the light that exits the lens. Many factors determine how each lens filters light.

It is difficult to create contrast when the light, entering the lens inherently lacks contrast. However the opposite is not true. This is because high contrast increases information content. Just think about the difference between a gray card (limited information) and the sunny beach scene (much more information). The data from the beach scene can be modified to increase its linearity (reduce contrast). But the gray card data is devoid of non-linear information and applying non-linear functions only affect it's width and position while the distribution (shape) remains essentially constant.

 

[pgk]

The main question then: is there any difference between the natural contrast of a lens and just upping up the contrast in Lightroom?

The answer is yes.

The 'natural contrast' as you describe it, is in essence the scene contrast less the reduction in contrast due to the lens (caused by veiling flare). What this does is to reduce the tonal information available in the shadows as the veiling flare adds light to the shadows. So a low contrast lens (more veiling flare) will have less shadow tonality than a higher contrast lens and no amount of adjustment in software can reinstate this.