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02-03-2009, 11:59 AM   #1
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A Lens' Color Rendition

I have always wondered what attributes give one lens "better" color rendition. I see this posted numerous times regarding one lens or another. If two lenses of same focal length, aperture, etc. take a shot of the same scene/light, what characteristics of the lens give it this quality? Of the better glass available from all manufacturers, aren't they all made with optical clear glass? I can understand conceptually that distortion and resolution can change given different optical designs. But, I have a harder time understanding how say a shade of a green leaf appears to be a more accurate representation with one lens over another. Certainly, it must be more than the SMC coatings as even within the Pentax lineup I still here the same discussions.

02-03-2009, 12:39 PM   #2
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I feel there's at least a couple of different things going on with this topic.

First, every lens has slightly different transmission characteristics - often very minor indeed - but these do make for definite trends - some lenses tend to a cool look, others to a warm one, or some may favor say greens over other colors. This would be due to the glass used and the coatings.

The second and maybe more important characteristic is what I'd call 'color contrast' or 'density'. This is contrast in the area above absolute resolution where a lens designer has choices to make. By giving the lens a slight bump in this region, the eye perceives a greater sharpness, contrast, color rendition in the photo.

The elimination of glare flare allows this contrast to develop. That is, a lens that suffers from this type of flare will look relatively washed out when there is a strong side lighting situation.

The two lenses I think of in this context are the Pentax 16-45/4 and the Tamron Adaptall 35-80 SP CF. The older Tamron I've verified has better absolute resolution. But the Pentax has the better contrast and pop. The color rendition of the Tamron is less intense and, well, colorful, than the Pentax lens'. And the Tamron suffers from glare flare to some extent.

Comparing the 16-45 to the 43 Limited was instructive. The 43 looked less contrasty and dense... but when looking at histograms and really peering into shadow detail, in fact the 43 has greater total contrast (latitude) and definition. And the 43 of course out resolves the zoom.

But what's more natural? Often we ooh and ahh over the slightly better than real colors and contrast of something like the 16-45. And by all means it's a very good lens and makes excellent photographs. Just that for me, the 43, and even the Tamron within its limits, are better and more accurate. Not always more exciting though

[With color rendition, then you get into sensor characteristics and geometry & how these lock onto a given lens, plus all the processing algorithms etc etc etc.]
02-03-2009, 01:20 PM   #3
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Wish I had a good answer for you. And I'm one of the guys "throwing around" the color rendition issue.

I first noticed the difference when comparing shots taken through the A*300/2.8 to similar shots taken through the FA*300/4.5. Especially in heavy open shade--ie very blue light from the blue sky "reflector"...The FA* lens was far less blue in it's renderings--though still certainly not warm in that light. The FA* still had pretty decent "pop" to the colors. Most noticeably the reds, greens and browns. The A* is no slouch and has tremendous contrast and sharpness and such, but the images have a very noticeable and different color cast than images shot through the FA* lens family--not just the 300/4.5.

The A*200/4 macro has less color difference from the FA* family and in fact, I think I prefer the A* to the FA*200 macro in this regard--but just slightly...Note that the differences in the A*300 colors are not to be taken as a flaw...just a subtle distinction and probably more for splitting hairs than judging photos. Used in good light, the differences are almost non-existant to my eye.

My untrained guess? I believe that the use of ED lens element(s) is designed to reduce chromatic abberations from the unequal focusing point of each color band of light. That's a fact, and my guess is that slightly different qualities of ED color correction result in slightly different color casts from the earlier * lenses to the more recent.

A similar phenomenon is noticeable with the F* and FA* 600/4 lenses when adding the 1.4XL teleconverter. Even in full sun, green shades lose contrast and thus lose their pop. Reds and browns a bit too. This could have something to do with the ED idea or more likely ties into the contrast discussion from the earlier response to your post. This is because teleconverters almost always reduce contrast. But I'd bet that teleconverters also change the focus point of various light bands too.

So now you have no better answer--from me anyway--than when you started this post. But I can vouch for the color rendition differences and have noted it in multiple lenses and multiple circumstances. So it exists, I'm just not precise regarding telling you why. How about non* lenses? I don't know, I've never owned a non* A lens...
02-03-2009, 03:55 PM   #4
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QuoteOriginally posted by MSM Quote
I have always wondered what attributes give one lens "better" color rendition. I see this posted numerous times regarding one lens or another. If two lenses of same focal length, aperture, etc. take a shot of the same scene/light, what characteristics of the lens give it this quality? Of the better glass available from all manufacturers, aren't they all made with optical clear glass? I can understand conceptually that distortion and resolution can change given different optical designs. But, I have a harder time understanding how say a shade of a green leaf appears to be a more accurate representation with one lens over another. Certainly, it must be more than the SMC coatings as even within the Pentax lineup I still here the same discussions.
My own opinion is that coatings can make a big difference.

Try this:
1. 38 year old TAK 105mm
2. New Sigma 105 macro

Both taken under exactly the same conditions with no PP whatsoever except for down sizing. F/8 natural light.

I don't see much difference in color myself.


Last edited by wildman; 02-23-2009 at 05:02 AM.
02-03-2009, 04:20 PM   #5
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Could just be the exposure difference (about a half stop difference it appears) but the reflected glare off the leaves in the top photo is very blue. Much closer to white in the bottom photo, but again, that may just be the exposure difference between the two lenses.
02-03-2009, 04:25 PM   #6
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I'm looking at a tiny screen laptop and can't see both photos at the same time like most "real" computers. But look, the table is much warmer brown tone in the bottom image than in the top. There's the cool tone vs warm tone example people may be looking for.
02-03-2009, 04:31 PM   #7
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QuoteOriginally posted by Ron Boggs Quote
I'm looking at a tiny screen laptop and can't see both photos at the same time like most "real" computers. But look, the table is much warmer brown tone in the bottom image than in the top. There's the cool tone vs warm tone example people may be looking for.
The Sigma is warmer, but the Takumar is sharper. So what do we get from 30 years of evolution? Warmer and softer.

Sigma coats their lenses with Lenor.

02-03-2009, 04:34 PM   #8
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That means no static cling either!

02-03-2009, 06:14 PM   #9
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The TAK definitely out resolves the Sigma (although I love my Sigma 70 macro). Look at the leaf that reaches the furthest to the right....

The tak photo you can easily identify the white hairs coming off the leaf. In the Sigma you can barely make it out.

Both are fine, but both are subtly different.

c[_]
02-03-2009, 06:38 PM   #10
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There are quite noticeable differences at least among Pentax lenses imo. I find the older M series to be noticeably cooler in colour rendition. It gets warmer with the FA series which I like. The DAs exhibit clearer overall contrast. Just my observations.
02-03-2009, 07:22 PM   #11
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QuoteOriginally posted by ll_coffee_lP Quote
The TAK definitely out resolves the Sigma (although I love my Sigma 70 macro). Look at the leaf that reaches the furthest to the right....

The tak photo you can easily identify the white hairs coming off the leaf. In the Sigma you can barely make it out.

Both are fine, but both are subtly different.

c[_]
I think that's just a focusing issue, though, in that shot. A MF tak focused precisely
is not going to have any FF/BF.

I think color rendition is hugely a function of coatings and the use of good glass, like
ED, etc. A lens with great contrast is going to have the best color, they're almost
functionally the same measurement.

Color cast is another issue - a bluish cast can be pleasant in some situations,
but most people prefer a warmer cast.

Below was taken with the Vivitar/Kiron 75-205 f/3.8 - a very sharp zoom with
excellent resolution, but not the greatest color - I wish I had another shot
taken with another lens to compare, but after shooting these a lot, I always
can notice the characteristics now, hope it's apparent:



Below was taken with the Vivitar Series-1 105 2.5 macro - it has better colors
than the zoom above, but has a bit of a bluish cast:





Almost all Multicoated Pentax lenses just have great, great color, maybe some
cast either way, but still great, IMO. My Nikon D80's 50 1.8 just doesn't have
the color-pop the Pentax 50's seem to have, although it's a different sensor
than my K20D, different rendering engine, etc, so I don't know how much I
can attribute to the lens:

Nikon D80 + 50 1.8


K20D + Super Tak 55 f/2


K20D + S-M-C Tak 50 f/1.4 (thorium-yellowed + fungus):



But maybe the best color I've seen so far from a non-Pentax lens has been my
Sigma 70 2.8 EX DG macro:






Or maybe the Voigtlander Nokton 58 1.4:






I know these are not 'test results', I'm just trying to illustrate what I can
see in making 1000's of shots - I guess it's kinda like a wine taster putting
a glass in front of you and 'telling' you what you should taste - it's apparent
to someone who has experienced the huge sample period beforehand


.

Last edited by jsherman999; 02-03-2009 at 07:28 PM.
02-03-2009, 07:31 PM   #12
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QuoteOriginally posted by MSM Quote
I have always wondered what attributes give one lens "better" color rendition. I see this posted numerous times regarding one lens or another. If two lenses of same focal length, aperture, etc. take a shot of the same scene/light, what characteristics of the lens give it this quality? Of the better glass available from all manufacturers, aren't they all made with optical clear glass? I can understand conceptually that distortion and resolution can change given different optical designs. But, I have a harder time understanding how say a shade of a green leaf appears to be a more accurate representation with one lens over another. Certainly, it must be more than the SMC coatings as even within the Pentax lineup I still here the same discussions.
I'll try my best to add some "sane" content (as opposed to LSD-inspired content) to this thread:

The image quality of lenses for digital photography. Jos. Schneider Optical Works

Scroll down to "spectral transmission." Note how the line in the graph is not flat--and it's different for different lenses.
02-03-2009, 07:45 PM   #13
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QuoteOriginally posted by asdf Quote
I'll try my best to add some "sane" content (as opposed to LSD-inspired content) to this thread:

The image quality of lenses for digital photography. Jos. Schneider Optical Works

Scroll down to "spectral transmission." Note how the line in the graph is not flat--and it's different for different lenses.

Nice link you found, asdf!

Here's the meat, in regards to color transmition, the OP's question;



QuoteQuote:
Good light transmission by the lens (spectral transmission)

The capability of making good pictures, even at low levels of illumination, is assured by the high speed of the lens, which is described by reference to the aperture ratio (e.g., 1:3.5) or f-stop number k (e.g., k = 3.5). The lower the f-stop number k is, the faster the lens. This f-stop number, however, does not take into account the reduction of the light as it passes through the elements of the lens. This light loss results from absorption (reduction) in the lens elements, and because of reflections at the air/glass interfaces, and is dependent on the color (wave length) of the entering light. Good light transmission (spectral transmission) is achieved only with high-quality optical lens elements and with very good coating (elimination of reflections) at the surfaces of the lens elements, using numerous extremely thin systems of layers applied by an evaporation process. The spectral transmission is expressed in percent in dependence of the color of the light (wave length).
02-03-2009, 09:04 PM   #14
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I believe the color cast of a lens is related first to the type and thickness of the lens element coatings and then second to the specific type of glass used for the elements. It's important to note that lens manufacturers routinely state the percentage of light a given lens can transmit to the film plane or sensor but they never go into the details of what light is lost in the process. Perhaps the color cast of a lens is more about what is subtracted than what is presented.

The issue of the types of glass used is interesting though. I tend to recognize a given lens as either having or not having a beautiful color cast to it (one of my better lenses being a Kiron made 135/2.8) but beauty is subjective. There can be a difference between pleasing color and accurate color. I believe many of us turn to older lenses simply because they utilize elements made of glass. Some modern lenses having plastic elements or hybridized polymer-glass elements produce wonderfully accurate colors that in the end seem flat.
02-03-2009, 10:13 PM   #15
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While it is certainly possible I'm having a flashback (hey, were you at that concert too?), ED lens elements are specifically designed to create a common focus point for the various colors. You know how a prism breaks the colors into their own "band" to create a rainbow effect? Lens elements also do this to a lesser extent. Well, ED elements are designed to adjust those colors back into a single focus point rather than each color having it's own separate band and separate focus point. If you do a bit of research on what ED elements do and what APO means, you'll see that ED elements are all about "tweaking" the colors as they pass through the lens. Since each ED element and each era of ED engineering can vary, so too can the way the colors pass through the lens vary. That's where my "flashback" comes from...so it isn't quite as trippy as it may seem. Wow man, tracers!

And regardless of why (sometimes the techy part isn't as pertinent as we make it out to be) the fact is, various lenses render colors differently. Pretty much every post and every photo in this thread proves that point. So when you chose lenses, you are also chosing a color rendition or color cast. I don't think any of us is arguing that point. And that's the main question in the OP--do the A lenses have a different color rendition than current lenses? I think the unscientific answer is "most definitely".
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