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05-15-2014, 12:28 PM   #1
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Why do some lens produce superior skin tones

I have to admit, I'm a noobie to portrait photography but recently picked up a portrait prime (Voigt Nokton). I've only used it a few times but I am really impressed with the how it renders skin (mostly) and clothing to some extent. I am curious as what technical lens qualities (assuming that there are) that would produce better portrait images. I don't think the answer is magic pixie dust but it may be. I have started a list of things of the obvious:
  • Color rendition
I would appreciate your thoughts or knowledge.

05-15-2014, 12:39 PM   #2
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QuoteOriginally posted by Dice Quote
I have to admit, I'm a noobie to portrait photography but recently picked up a portrait prime (Voigt Nokton). I've only used it a few times but I am really impressed with the how it renders skin (mostly) and clothing to some extent. I am curious as what technical lens qualities (assuming that there are) that would produce better portrait images. I don't think the answer is magic pixie dust but it may be. I have started a list of things of the obvious:
  • Color rendition
I would appreciate your thoughts or knowledge.
Partially worn off lens coating can make the lens render effects unintended by the manufacturer. Old glass should be viewed as a living organism, and I am not referring to fungus! My Konica 40 1.8, Konica 50 1.7, Helios 58 2.0 outshine all of my modern lenses.
05-15-2014, 12:41 PM   #3
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Often see lenses described as rendering "cooler" or "warmer" and I've wondered as well what exactly causes that. I would think the coatings would be a big factor and perhaps the makeup of the glass. I always thought of 'glass' as well, glass. But the material used in optics has properties that are altered by the chemical makeup and any additives included.

I know in the steel industry that formulas and additives are closely held secrets as even minute amounts of other metals added can dramatically alter the physical properties of the final product. I would assume the same thing is true in the optics industry.

Note also that it has been mentioned that some older lenses are no longer in production because the glass used in them is no longer available, possibly because of environmental or health regulations. The radioactive glass used in some Takumars for example.
05-15-2014, 12:44 PM   #4
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QuoteOriginally posted by jatrax Quote
Often see lenses described as rendering "cooler" or "warmer" and I've wondered as well what exactly causes that. I would think the coatings would be a big factor and perhaps the makeup of the glass. I always thought of 'glass' as well, glass. But the material used in optics has properties that are altered by the chemical makeup and any additives included.

I know in the steel industry that formulas and additives are closely held secrets as even minute amounts of other metals added can dramatically alter the physical properties of the final product. I would assume the same thing is true in the optics industry.

Note also that it has been mentioned that some older lenses are no longer in production because the glass used in them is no longer available, possibly because of environmental or health regulations. The radioactive glass used in some Takumars for example.
I'm not a big fan of the colour rendering of my Tamrons: yellow always looks "ill" and adjusting white balance doesn't help much. The Pentax kit lenses render dull colours as well.

05-15-2014, 01:21 PM   #5
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QuoteOriginally posted by DominicVII Quote
I'm not a big fan of the colour rendering of my Tamrons: yellow always looks "ill" and adjusting white balance doesn't help much.
I've never heard it described that way (or that well)! But I think it's a key reason I no longer own any. And the exterior color scheme of modern Tamrons only reinforces this impression in one's mind.
05-15-2014, 01:44 PM   #6
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Not an optics expert, but let me give you a simple example that might explain some of what is likely going on. You could create a green light source by having a bulb or LED emit just a the green frequencies of light. Or you could combine a yellow and a blue source to give something that the eye perceives as green. Now if you have a lens that lets all the light through uniformly across the spectrum, both will see these lights as green. But if lens biases and lets in more yellow than blue, or thinking in reverse it filters out more of the blue light, your camera will see something that is a different tone or shade of green. The same was true back in the days of film, where the different companies had products that were known to be better for different types of photos because of how well the different layers within the film captured the different colors.

Different thought experiment, but an even simpler one to do. How does your skin tone change when standing under daylight, fluorescent lights or incandescent lights? Photography is all about capturing light and the properties of the lens are just part of the equation.
05-15-2014, 04:59 PM - 2 Likes   #7
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I don't think this is a skin tone issue.


Neither is it a coating issue or worn off coating issue.


Lens design is hugely complex and the modern fetish for sharp designs and sharp images in my opinion is a blind alley many photographers find themselves in and never get out of.


Ultra sharp is good Razor sharp is better, Highly saturated is good. Nothing could be further fro the truth.


You might like to see pixel sharpness in your images and hunt for ways of achieving images so sharp you an bleed when you handle them and some images need razor sharp. But the most beautiful images are unsharp.


Are we trying to produce technically brilliant work that people appreciate or beautiful images people fall in love with.


You have now seen the light. A portrait lens is not super sharp nor is it highly saturated or super contrasty. I could rant on for hours about Duplets, Triplets, Cooke Triplets, Planars, Tessars, Pancolars, Sonnars, and their characteristics and why they yield gorgeous images far superior to modern lenses.




We are not talking about blurry pictures you can get by defocussing or by blurring in photoshop. We are talking about a soft lens with gentle hues and gorgeous bokeh.


Quite unlike anything a modern lens can achieve.
05-15-2014, 05:19 PM   #8
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Thanks for the great discussion everyone. I am curious if others also feel there is some sort of balance that is achieved optically with the lens being sharp (probably not the right technical term but there it is) but not overly sharp in the typical apertures used.

I do like the idea (and subscribe to without any facts to back it up) what Jatrax says about additives when formulating the glass.

05-15-2014, 05:29 PM   #9
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I have also noticed something too about how some lenses I use on the same camera K-5IIs give better color rendition such as skin tones. The lenses I am referring to are the older lenses from Topcon camera era. I have my other 3-amigos, namely, Auto-topcor 58f1.8, 35f2.8 and 135f3.5. All these lenses provide superb sharp images at wide-open aperture. I converted all of them to m42 lenses so I can use them on my k-5/IIs and k-01 cameras. My only reasoning for its ability to render nice color is in the lens coating.
05-15-2014, 05:29 PM   #10
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QuoteOriginally posted by Dice Quote
I do like the idea (and subscribe to without any facts to back it up) what Jatrax says about additives when formulating the glass.
There may be aging effects as well, but there's clearly a difference in the glass (or coatings) itself when two 'optically identical' lenses (e.g. an F and an FA, such as with the 135/2.8) give a slightly different color rendering.
05-15-2014, 06:50 PM   #11
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Part of the reason is that modern optical designs have aspherical lens elements and other things that while improving the numbers, create sterile image rendering.
05-15-2014, 06:53 PM   #12
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I'm not sure either. However, as one example, a few reviewers cited the old F 70-210 as producing good skin tones. The lens reportedly has 9 aperture blades, good saturation, and good though not great sharpness. I of course do not know if these are lens attributes that make for good skin tones. If one could get a list of the lenses that reportedly give good skin tones, and then look for possible similarities, that may provide some clues. In the analog days good skin tones were often attributed to the film properties but now it is different, I would guess.
05-15-2014, 07:02 PM   #13
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QuoteOriginally posted by DSims Quote
There may be aging effects as well, but there's clearly a difference in the glass (or coatings) itself when two 'optically identical' lenses (e.g. an F and an FA, such as with the 135/2.8) give a slightly different color rendering.
That's very interesting. So that may add some credence to the idea of aging. I have a sense there is a little bit of truth in what everyone has suggested.
05-15-2014, 07:48 PM - 1 Like   #14
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QuoteOriginally posted by y0chang Quote
Part of the reason is that modern optical designs have aspherical lens elements and other things that while improving the numbers, create sterile image rendering.
Very true, as far as I can see. The Zeiss OTUS 55/1.4 is a great example here. You can get older lenses that produce more beautiful images, but this $4000 wonder does an amazing job of balancing good measurements with beautiful images. The competing Sigma 50/1.4 Art is more biased towards the measurements (even though the OTUS beats it in measurements too). In contrast, a third new lens - the badly maligned Nikon 58/1.4G - is biased toward beautiful images. While it may be disappointing in some respects, it appears incapable of producing the busy backgrounds that can come out of the Sigma.

People decry the high price of the OTUS, apparently not realizing how impossible the goal is - a goal it has nearly reached! At the same time many praise the suddenly-affordable-looking Sigma. And the Nikon is often regarded as an absolute waste of money. I think this shows how much people's thinking has changed in the digital age.



BTW, some Pentaxians are really hoping the Sigma will be released soon in K-mount. Sometimes we forget that the Pentax DA*55/1.4 was already (but many estimations) the best 50ish lens around - until these new lenses came along. Like the Sigma, it can produce (a different kind of) busy background. But the overall images look nicer, I think.

For those who want the appearance of a "modern" 50, the DA*55 is still the best you can do for less than $4K.

Last edited by DSims; 05-15-2014 at 07:55 PM.
05-15-2014, 07:54 PM   #15
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I would say it's coating... generally speaking, euro glass render rather cold (blue-ish) and japanese glass is warmer (yellow-ish).
But PENTAX is closer to favor green...
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