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Colour Space.
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PostPosted: Tue Apr 17, 2007 7:24 pm    Post subject: Colour Space. Reply with quote
There are still many experienced users who believe the lens has an influence on colour in digital photography, when in fact digital cameras do not record colour and can’t tell the difference between one shade of red and another. It’s the PP that sorts the colour out as any RAW shooter should know. You set the colour balance, you adjust hues and saturations you set and adjust highlights, shadows and contrast.

This evening I was just doing final adjustments to today’s blossom pictures (Today in Gallery) when I almost fell into the trap myself by thinking ‘Nice. This lens baby does a good job with colours’ Of course it is nothing to do with Lens baby, it was just everything was right with the RAW conversion. I then got to thinking about others and what colour space they may be using?

If (And you should be) you are shooting RAW no colour space is set until conversion, so it pays to use the best available. Colour space determines where or how far the colour balance, hue and saturation can go. The best for a 16 bit file is ProPhoto. It contains a range of colour tones that far exceeds your humble sRGB or Adobe RGB. It contains so many that your monitor won’t actually show them all but they are there. Set conversion to ProPhoto and make sure colour management in Photoshop is on. After you have done all your fine adjustments then convert to your working colour space sRGB or Adobe RGB and down to 8 bit (Always sRGB for the web) You will find a lot more fine control of colour in ProPhoto colour space and I find much more room in the highlights.

If you switch between colour spaces in PS Image – Mode - Assign profile with preview ticked you will see the difference the colour space makes to an image. Doing that also demonstrates that a lens or for that matter different camera sensors make no difference to colours.

A lens will of course influence contrast and tones but don’t mistake that for colour. A low contrast lens may wash out the colours but they are still there to the same degree as the BW tones recorded for them but again only PP can determine and influence the hue and saturation of those recorded values. In other words if the image was only processed to BW it will still be, compared to another lens low contrast or ‘Washed out’. The colour hue has nothing to do with it.

There is no such thing as a 'Warm' or 'Cool' lens in Digital. Also there is no such thing as a normal or default setting for the camera unless you are going to leave all such things to the judgement of a blind camera proccesing engine.

I'm sure this will start some discussion.


PostPosted: Tue Apr 17, 2007 8:51 pm    Post subject: Reply with quote
I won't argue into a technical discussion because I don't have the necessary scientific background. I would not even call myself a "photographer" because I lack many technical notions. I am only an unknowledgeable person who enjoys to try to make art with photographs.

I only want to add that my eyes perceive a difference between lenses with regards to color saturation, even with digital.
If this is not scientifically possible, then maybe I have a problem with my sight.

But then I would like to know why Zeiss today still spends millions in color testing each one of their lenses if the lens is totally irrelevant in the color process. And they surely are aware that today, they are selling lenses to digital camera users.


PostPosted: Tue Apr 17, 2007 10:15 pm    Post subject: Reply with quote
Orio wrote:
I won't argue into a technical discussion because I don't have the necessary scientific background. I would not even call myself a "photographer" because I lack many technical notions. I am only an unknowledgeable person who enjoys to try to make art with photographs.

I only want to add that my eyes perceive a difference between lenses with regards to color saturation, even with digital.
If this is not scientifically possible, then maybe I have a problem with my sight.

But then I would like to know why Zeiss today still spends millions in color testing each one of their lenses if the lens is totally irrelevant in the color process. And they surely are aware that today, they are selling lenses to digital camera users.


I believe what you write about enjoying the art of making photos to be the most important thing. One doesn't have to have all the scientific knowledge but it does help if you have a true perception about the media you working with, but at the end of the day I would rather know a good photographer who hasn't a clue how it works and doesn't care than a so called expert who can't show a photo.

Zeiss or any other manufacturer spending millions on colour testing lenses? In what colour space are they testing them and in what colour space are they making any corrections for? One only has to togle between colour spaces to see the point.

Of course an answer could be they are testing and correcting lenses for those who are still using film or for those who just go by the limited standard of a camera corrected JPEG file straight from the camera. The whole argument that lenses do not control or have an effect on colour only applies to those shooting RAW and have a basic understanding of conversion. Such a basic understanding means colour balance and fine adjustments of colour hue and saturation in conjuction with exposure and contrast in the RAW converter

This is the point of it. as somebody who wants to take photos and enjoy doing so it does help to know that a lens doesn't restrict your choice of colour or tell you what colour a shade of red or green should be. By using your choice of the best colour space available you make the choice and in doing so you get the best from your top quality lens. You may also find that the qualities you so like in your lens are not the colour. they are a bit more meaningful than that. That understanding may then help you get even more from that lens.

I should add some of my fav lenses (for some subjects) the older Tamron adaptall ones produce an image I like because of the percieved colour. However it is nothing to do with colour it is that these old adaptalls have their max contrast at around 25 lpm. Plenty of detail to the naked eye and certainly plenty to resolve lots of detail in the subject but not enough to give those stark sharp edges that sometimes don't really help the artistic quality of a photo and not enough to give (Straight from the camera) very saturted colour tones. Of course can one if wished soon up those colour tones to a more normal level and still retain a nice smooth edge sharpness and some nice graduation between colours. The contrast and in some cases a little internal flair has a great effect on tones but no real effect on hues, saturation or colour balance. The colour effect is just pervieved because of the contrast, you can in RAW conversion and PS do what ever you want with those colour tones and of course they are all controlled by the colour space you are using.


PostPosted: Tue Apr 17, 2007 11:42 pm    Post subject: Reply with quote
How is that photographs taken with my Summicron-R 50 are so saturated that they never need a boost (and actually sometimes they would use a reduction!), and photos taken with my Canon EF-50/1.8 can use as much added saturation as you like?
They are both highly contrasted lenses. And both are very detailed. So they are similar for those respect.
Another example, staying in the autofocus lenses, all my Canon EF lenses need saturation boosting, the 100mm/2 especially, and Sigma also (actually even more), while my Tamron 18-200 produces images that are more saturated without a polarizer than the aforementioned lenses _with_ a polarizer?

These are just the first examples that come to mind, I could probably make more.

Another example of how glass can influence color is the polarizers. I made yesterday the comparison test of my B+W polarizer against a cheap polarizer, both 55mm diameter. The B+W filter does not alter the color rendition, the cheap polarizer casts a blueish hue, no doubt due to the less expensive coating. I'm talking about digital. The cheap polarizer actually influences the color hue as perceived by the sensor. I have the tangible proof of it.
This is about hue however. I think that glass difference is more or exclusively about color saturation.

I am of the opinion that different glass can give different color saturation. I can not, however, bring any scientifical reasoning in support. So I guess I'll just stay with my belief. Smile


PostPosted: Wed Apr 18, 2007 12:42 am    Post subject: Reply with quote
You are right IF you had no control of colour in RAW conversion or Photoshop.

Again my first question would be in what colour space and at what settings do you see these differences. If as I suspect it is in relation to other lenses that is again right. But There is no such thing as a normal or a default setting for the conversion or adjustment to an image. Colour balance , colour hue and colour saturation and most inportant Colour space are at your control with no ill effect on the image as long as it is done in RAW conversion.

If colour is completly at the control of PP then a lens no matter what it does has no effect on the colour of your finished image. Who is to say what the correct colour setings are? Canon have their idea of what it should be and Leica have theirs. You shoot digital so their idea of colour doesn't make any difference to you, You do it as you want it. Thus the lens has no effect on the colour of your digital image. Whatever examples you think of the question must always be at what settings and why are those settings the right ones? Even if it is relation to another lens in controled exposure and colour temp settings it makes no diference. there is no true default colour settings when coverting a RAW file or any default colour space that must be used for making adjustments. if you were shooting colour film then you should worry. But we are lucky we use digital and it is worth getting around to using its advantages and throw away some of the old ideas that come from film restrictions and in the case of colour IMO the major faults of film.

As for the polarizer that has nothing to do with colour It cuts out reflected light rays as for example the reflective light is reduced from the sky and the tone is darkened. Another example a pool of water will reflect the colour of light reflected in it, cut out the reflection and you stop that.

PS there is very interesting reason for the Summicron-R 50 characteristcs which I recently read. I will find it for you and post a link.


PostPosted: Wed Apr 18, 2007 1:48 am    Post subject: Reply with quote
Why are you talking about "what color is right"?
I never put it this way. I talked of saturation. This is where I perceive the difference. If I take a shot with the Summircon 50 and boost the saturation, it gets almost immediately clipped. If I do the same with a Canon EF 50, it takes a mile before it gets clipped. Why? The RAW image parameters are the same. So what other than the lens, could have influenced the saturation?
I see no other possible explanation other than the Summicron glass did saturate the color more to begin with.

About the parameters, I use always the same parameters in camera: contrast = normal saturation = normal sharpening = 0 color hue = 0 white balance = automatic (when I do not make a custom WB shot).


PostPosted: Wed Apr 18, 2007 4:53 pm    Post subject: Reply with quote
http://luminous-landscape.com/tutorials/understanding-series/lens-contrast.shtml
This is the link to the bit about the Summicron I read, though I'm not sure if it is the same lens. It is worth reading the whole article even though it was written for film. There are many references to colour and the characteristics of lenses. Here is the Summicron bit.

“In my opinion, lens contrast of fairly large image structures is a primary determinant of subjective optical quality in a camera lens. The old Leica 7-element 50mm Summicron was optimized for high contrast at 5 lp/mm, for instance, and under favorable picture-taking circumstances (i.e., avoiding too much flare and too wide an aperture), these lenses can still yield glorious-looking pictures today.
Also, it's very interesting to note that high apparent lens contrast can be simulated digitally, and this may eventually prove to be an Achilles heel for silver-halide photography where viewer appeal of prints is concerned. "Sharpening" only improves visual microcontrast, of course, not actual resolution of detail. But resolution of very fine structures seldom helps pictorial photographs much, and, in my opinion, is an overrated property where lens quality is concerned.”

Other articles well worth a look at. All the below deal with subjects that have a great deal of rubbish talked and written about them (like a lens with 400lpm resolution) it is worth reading some sense from guys who actually take, exhibit and sell real photos.

A good primer in digital colour
http://luminous-landscape.com/tutorials/whats-the-problem.shtml

Understanding RAW files
http://luminous-landscape.com/tutorials/understanding-series/u-raw-files.shtml

Understanding Polarizers
http://luminous-landscape.com/tutorials/polarizers.shtml

Understanding sharpness
http://luminous-landscape.com/tutorials/sharpness.shtml

( My opinion) Lens resolution and particularly lens contrast and at what resolution the best contrast of a lens falls or is optimised for is IMO the answer to all this perceived colour differences and characteristics of a lens. It is a fact that it is the answer to why we like a particular lens. Armed with this knowledge one can PP an image better and get the look we like. Of course all other technical areas of the image also have to be right. If the mage is over or under exposed, the RAW conversion done without knowledge or care then all I lost.
Luckily with digital it only costs us time and effort to shoot loads of image and practice till we begin to get it right I’m still trying and hope to still 'Only be trying' till the end of my days. What's the point if you always get it right with ease?. Or worse are satisfied with all your results?
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