NikonGear'23
Gear Talk => Lens Talk => Topic started by: Michael Erlewine on March 05, 2016, 14:05:46
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First, I probably have not done this right, so if you will point out (within reason), I will try to find time to do this again. Here is what I did do, using the Nikon D810.
(1) Took photos at night using two 5600K LED lights.
(2) More or less tried to frame them the same, but hard to do because they are very different.
(3) Tried to use f/5.6
(4) Use Passport color checker only in photo (not internally).
(5) Brightened exposure to make them roughly equal.
(6) Did NOT do any retouching or use of white-balance eyedropper
(7) Focus point was tip of light leaf.
The photos are labeled by lens, but they are, in order:
El Nikkor 105mm APO
CRT-Nikkor
Noct Nikkor
Voigtlander 125mm APO-Lanthar
Otus 55mm
Otus 85mm
Otus 28mm
Now, what should I do instead of what I did?
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My preferences are in this order: Voigt followed by Noct followed by Otus55
Reason: General look and feel.
Voigt sharpness + bokeh + lack of coma
Noct: Ohhhh those colors + Pity on Line on leaf
Otus 55: Surgical and boring but wins on technical.
What say you?
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I would want to adjust each one based on the color-checker and remove color casts, etc., which I did not try to do in these shots.
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Common lenses? It's not like they are in every photographers bag ;)
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Børge, my thought exactly :)
The only common thing about these lenses is that they are not common :)
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Børge, my thought exactly :)
The only common thing about these lenses is that they are not common :)
Well, common to me and my work. Must be some other comments, like I would color-correct all of these, etc.
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Børge, my thought exactly :)
The only common thing about these lenses is that they are not common :)
I agree with your comment. Another commonality are that they are not for common people. I will now commence further commenting in this thread ;D
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What I was looking for are suggestions on how to go about comparing color from different lenses. Perhaps someone could comment on the thread, not on the title. I should have written "Color Cast for Some Commonly Remarked on Lenses." After all, this is NikonGear. We commonly look at all kinds of uncommon lenses.
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Assuming you have PhotoNinja or similar, for each lens build a session profile by shooting the Color Passport or Color Checker card under the same light conditions and apply this when the files are processed. This simple remedy should ensure the maximum of colour consistency across the lenses.
However, while you can, to some extent, equalise colour rendition post shooting this way, the lenses still will appear different simply because they *are* different. For example, the CRT Nikkor is not designed for use under white light and thus does not draw colours equally distinctly as the CV 125 APO. The clinical nature of the Otus lenses still will contrast that of the temperamental Noct-Nikkor or the the rounded, pleasant rendition of the CV 125. And so on.
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Sorry! I couldnt help myself. I find it very hard to compare different color cast, even when I am using colorchecker. I usually only divide them into warm and cold. The warm ones are more to the red/yellow side and the cold ones more on the blue/magenta side. But on the other hand, if I color correct, I take away the signature of that lens and the picture is just one of many.
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You can only control colours so much, as I implied. A lens character will remain. If the lens design cannot properly deal with, and differentiate between, colours in the first place, you cannot correct colour rendition perfectly post facto.
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You can only control colours so much, as I implied. A lens character will remain. If the lens design cannot properly deal with, and differentiate between, colours in the first place, you cannot correct colour rendition perfectly post facto.
Can you list how best, if any, to show how different lenses (common or uncommon) draw. How should I present this. Might as well educate me on this. What would be the best way to show a photo of each lens, so that it might be useful to others?
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But these lenses are chosen because they have no character. The only thing that differentiate them are the color rendition. Everything else is corrected away.
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I'm afraid this line of reasoning is beyond me, Børge. A CRT-Nikkor or a Noct-Nikkor both have a lot of character. Same goes for the CV 125 APO, which is less temperamental yet still imprints its drawing on the captures. Not familiar with the APO EL-Nikkor, but any enlarger lens is not designed for the same working conditions as an ordinary photographic lens.
The Otus lenses are designed to be clinical, though.
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Forgive me in what follows if you already know this stuff. Hard to keep track of who knows what. ;D
First shoot the CC Passport straight-on in good even lighting using each lens with exposures all at the same aperture and ISO. Try to fill the frame with the CC Passport but leave the focus very slightly blurred.
Next, using Photo Ninja, for each lens combo, create what is called a Custom Light Profile (colour correction) made from the CC Passport photo. This Custom Light Profile is automatically saved in PN's Color Correction tool so that it can be applied from a drop-down menu to subsequent photos made with the same combo. You can also create Presets containing the Custom Light together with other edits.
Once these Profiles are created you can compare the shots of the CC Passport colours as Before & After composites to see where or how the colour casts occur for a given lens.
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I wrote a tutorial (http://www.ultravioletphotography.com/content/index.php/topic/621-photo-ninja-how-to-make-a-custom-light-profile/) about Custom Light Profiles once and later I added a Before & After composite shot. I've attached that here to illustrate the point about comparing Before & After. I was a little fanciful and created a flower overlay in Photoshop for this. :D
The point I was making with my photos below is that merely white-balancing does not always fully correct colours. (This is especially evident when using full spectrum camera without internal filtration. It is not at all as evident when using normal, visible cameras.)
But for Michael's purposes, these photos illustrate a way to determine how a particular lens is affecting colour by comparing non-profiled and profiled shots for a particular lens. That is, by comparing uncorrected vs corrected colours.
This also gives you some material to directly compare two different lenses if desired.
Equipment: D600-broadband + 60/4.5 UV-Planar + Baader UVIR-Cut Filter
[Note to NG readers: the D600 internal UV/IR blocking filter was removed.]
(1), (2), (3) and (4) are the photo captions for the 4 photos which I can't match up in this forum software.
(1) BEFORE: The original photo with only in-camera white balance does not look too bad, but the yellow & purple are obviously off. The other differences are more subtle. Photo Ninja does a good job (at least in this example) of preserving the in-camera white balance preset.
Yes, Kitty Mocha contributed some cat hair to the orange patch. ???
(2) AFTER: The Custom Light profile created and applied. Corrected colours look better. Saturation can be further adjusted if desired.
(3) DIFFERENCE LAYER: The Before & After differences are not so easy to see when the two versions are separated. In Photoshop I made a difference layer to show where the differences occur. The difference layer was brightened slightly to make the difference locations more apparent because some of them are subtle.
(4) COMPARISON COMPOSITE: The After flowers atop the Before background show the PN corrected colour against the in-camera white-balanced colour. There are only the minorest of differences in the top monotone row. This means that the in-camera white balance setting made it through the converter (Photo Ninja) without major alternation. Do be aware that this may not always happen with other converters. The flower overlay illustrates that white-balance alone is not enough to fully correct colours in the broadband camera.
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Added to above -- Michael, you will need to think through how to handle white balance to make a proper comparison between one lens's uncorrected vs. corrected colour OR between two different lenses.
Should you make a new in-camera WB for each lens before shooting?
Or should you use a fixed Auto WB??
Or maybe just a Daylight WB setting??
Hmmmm....probably it is best to make a new in-camera WB for each lens because you want to get the very best from each lens prior to possible colour correction (profiling). Then look at its unprofiled vs. profiled colours.
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I used Photo Ninja in my example above. But I think there are other converters which can possible create profiles from the CC Passport. Lightroom maybe??
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Before someone leaps in here ---- sometimes we may not want to profile (colour correct) a lens. Sometimes we use certain lenses because of their colour cast or some other endearing quirk. But is it certainly useful to know, if possible, where the colour quirks are going to be methinks. :-*
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Very nice explanation Andrea. I have made color profiles for my most used light conditions, and lenses, in Lightroom. I use them sometimes, but most of the time, some corrections are necessary because of a slight change in the lighting. So, unless one have a extremely uniform light source, a in-camera WB setting is the preferred workflow, for me at least. And, Bjørn you are right. I assumed that Michael used only well corrected lenses with clinical rendering. I was wrong.
In my experience (which are somewhat limited, compared to many others here), at the end of the day there really is no neutral, when it comes to WB, color and hues, just approximations and qualified guesses.
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.....there really is no neutral, when it comes to WB, color and hues, just approximations and qualified guesses.
Definitely true! We haven't even taken into account such factors as monitors, ambient light in which an image is viewed, colour spaces and so forth. I'd say that the CC Passport thing is just a simple check to let us know the direction the colours are headed for a particular set-up.The reality is rather frighteningly complex. ;D
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What I was looking for are suggestions on how to go about comparing color from different lenses. Perhaps someone could comment on the thread, not on the title. I should have written "Color Cast for Some Commonly Remarked on Lenses." After all, this is NikonGear. We commonly look at all kinds of uncommon lenses.
Shoot each lens under same lighting conditions using the color checker passport, so that it fills the frame equally (i.e. change the distance between lenses to reflect their focal lengths), then either white balance using that, or even better create a color profile for each lens using that.
There will still be differences of course, but the main difference (different lens transmission in different wavelengths) is evened out.
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I understand how to make the DNG profile and restart Lightroom. Then go to Camera Calibration, select the profile of the particular lens/camera operation, and look at it. NOW, after that, what do you do with it. If it is just "tweak" it, well that is just more subjective stuff. Can someone explain what to do with the special profile?
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I would rather ask: why? The informal test shots (with the CC cards) all show a very non-neutral light source being used. I would start by replacing the light source by something more suitable to the task at hand instead of trying to equalise later.
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I would rather ask: why? The informal test shots (with the CC cards) all show a very non-neutral light source being used. I would start by replacing the light source by something more suitable to the task at hand instead of trying to equalise later.
I keep thinking there is something to accomplish here. What I end up understanding, is just keep doing what I have been doing and removing color cast, etc. as best I can. Nothing much to be gained from all of this, except to arrive back where I started, using my own taste. Does that make sense?
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Try using some quality studio flashes instead of LED lights. Then at least the emission spectra are continuous.
Adjust to taste? No problem. That is what everyone should do anyway.
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Try using some quality studio flashes instead of LED lights. Then at least the emission spectra are continuous.
Adjust to taste? No problem. That is what everyone should do anyway.
That's what I plan to do. I keep thinking that with a little testing, I will get to where people like you are, but I don't know what I am doing. I am better off just taking photos.
Thanks for the feedback and putting up with me. LOL.
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I understand how to make the DNG profile and restart Lightroom. Then go to Camera Calibration, select the profile of the particular lens/camera operation, and look at it. NOW, after that, what do you do with it. If it is just "tweak" it, well that is just more subjective stuff. Can someone explain what to do with the special profile?
In my very limited (2 camera bodies) experience with the DNG profile system, what I have found is that the Color Checker-generated profile does not provide 'perfect color' upon it's application to the file, but gets me closer... as a starting point for further adjustment.
Some more random thoughts:
The best way to see the color rendering differences between lenses is to look directly through them, by eye, at a sheet of white paper that is illuminated by neutral daylight. There, I have marveled at the distinct greeenish-yellow of many older, pre multi-coated lenses, the neutral to very slight green-blue color of most modern Nikon and Canon lenses, the pale lemon-yellow look of Leica M lenses, and the warm, orangey color from the Zeiss lenses.
Does this eye-looking have much to do with how the shots will look after digital post production? No....especially now, with wide-range correction available in digital post.
All of the differences that you can see by eye are reduced and/or modified by every stage in the post production processing of the photo: Raw converter, color and density adjustments, jpeg compression(if applicable), assigned [smaller] color spaces, and the final viewing medium: cheap laptop TN display, or luxurious color-calibrated ARGB monitor, or...printed on paper with a neutral white base, or a warm-toned base, using Canon ink or Epson ink, etc, etc.
Light sources: A comparison of color rendering of the lenses done under one specific light source applies to that light source, but maybe not to another light source. Especially in the case of LEDs and fluorescents tubes. LEDs and Flo tubes change over time, almost always toward the green.
This company, http://www.cineolighting.com (http://www.cineolighting.com), claims to have ameliorated some of the color issues with LEDs with what they call "Remote Phosphor" design.
I have used their units in television production, and they are heavy but well made. Did we conduct complicated, exacting tests of their light quality? No. We did like we always do: we look at the shot in a known, high-quality monitor, adjust the color response of the camera if necessary, and if it looks nice, we shoot it.
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I would rather ask: why? The informal test shots (with the CC cards) all show a very non-neutral light source being used. I would start by replacing the light source by something more suitable to the task at hand instead of trying to equalise later.
Noone asked Michal yet wich kind of light it is and which kind of white balance he used for the shots.
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Noone asked Michal yet wich kind of light it is and which kind of white balance he used for the shots.
Actually, I posted the light in original post, good LED lights. And I used standard auto WB.
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For my food shots I use lots of converter bulbs from Osram. 1.000 Watts Converter Bulbs of that kind
equal 10.000 Watts of classical incadescent light. The color fidelity is extremly high.
The series is called D65 iirc and is measured for RAL Farbscala as reference light RA98 meaning you get a 98%
color fidelity. If I take pictures with rather color neutral lenses like the 1.8/85G or the 2.8/60G or my large format
glass the change in calibration is hardly visible.
I do not think LED can do anything like what a 5 band or 6 band Fluerescent full spectrum source can do for you.
cheers
Frank
PS: yes. Professional studio flash can do the same for you after years of training and hour of setup
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I always use natural light, but here I used a constant LED. Not taking portrait shots, etc.
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Noone asked Michal yet wich kind of light it is and which kind of white balance he used for the shots.
He stated that initially. And LED lights are unsuited to doing a lens/lens colour rendition analysis because they don't have a continuous output spectrum.
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Actually, I posted the light in original post, good LED lights. And I used standard auto WB.
Auto white balance could be compensating for the color cast of any given lens which could skew your test. Since you are using a 5600K LED light, set your white balance in camera 5600k instead of auto. It is best to lock down white balance for tests, especially when dealing with color.
In case you are not familiar, adjusting white balance K temperature with live view on is a quick and easy way to see and set WB in ambient light situations.
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In case you are not familiar, adjusting white balance K temperature with live view on is a quick and easy way to see and set WB in ambient light situations.
I have set WB, but not in LiveView. How is the easy way to do that?
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Michael,
you might be interested in the DoE Factsheet on LED color characteristics
http://apps1.eere.energy.gov/buildings/publications/pdfs/ssl/led-color-characteristics-factsheet.pdf
Thanks for sharing your pictures and thoughts. Honestly, I am not yet sure what the objective is, but this might be completely my error. The current setup has imho too many variables in force, to be able to conclude specific lens attributes.
A few observations and thoughts:
1) There is no lens with an "official" Nikkor lensid in the setup. Any potential color cast of the lens hits the sensor and the WB engine of the camera, without the camera being able to "know" what the lens particular color rendition is. In my observation, Nikkor lenses which are "known" to the respective Nikon D-SLR (AF, AFS, ...) expose much less color variation, vs. older MF Nikkor lenses (or Zeiss lenses). It is my assumption (no hard evidence supporting this observation), that the lensid not only make the camera aware of some optical lens particularities like distortion, but might very well also provide some info about the color rendition of the lens type. Allowing the CPU (Expeed) engine to include this information in the overall WB process. Lenses unknown to the camera (even by typing the focal length and aperture into the camera), don't uniquely define the lens type to the camera. So, the camera software has to "guess" what the color rendition of the lens in use actually is - leading to more variation.
2) If you keep the camera WB setting on Auto during these test shots, the WB engine will compensate what it think is the most appropriate compensation. My suggestion: Freeze the WB setting to any value you think is the most appropriate and then do the test with all lenses. Then you can use the patterns on the color checker to measure deviations among the lenses under test.
3) I've put a paper by the dep of energy on LED color characteristics. LED is imho a bad light source for color testing.
If you compare the energy density of different light sources, you might appreciate the impact the light source has on the overall color rendition
Daylight and moonlight
(http://www.pbase.com/andrease/image/131695416/original.jpg)
A bulb (thats why the blue channel is usually the problem child in white balancing these pictures - lots of noise in the blue channel due to much stronger amplification needed)
(http://www.pbase.com/andrease/image/131695420/original.jpg)
High pressure sodium lights are particular mean to WB attempts with RGB sensors - there is just no energy in the other channels
(http://www.pbase.com/andrease/image/131695428/original.jpg)
3) The limits of color calibrated monitors. We are probably "verifying" the output of your pictures on our monitors. They could be not calibrated at all, could be calibrated by software, or by simple HW (colorimeter). Or more sophisticated HW (i.e. a spectrophotometer with 32 bands) which allows to compensate for different color rendition of different panel types (IPS, TN, ...). Is the ambient light in the room where the calibrated monitor is being used, calibrated as well? or not? Most likely, we will not see the same same color rendition we could discuss between us.
4) Not sure I understand the value of whitebalancing the existing images. Any potential color rendition difference of the lenses will be overlayed by software based assumptions the respective SW package will apply. But I might have missed the thinking behind this approach.
Thanks again for sharing.
rgds,
Andy
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I have set WB, but not in LiveView. How is the easy way to do that?
If you adjust the WB K temperature setting you can see the white balance change in realtime while viewing the LiveView screen.
By easy I meant that is a quick way to eyeball a neutral WB setting before you even take a picture, doesn't work with strobes, of course.
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I understand how to make the DNG profile and restart Lightroom. Then go to Camera Calibration, select the profile of the particular lens/camera operation, and look at it. NOW, after that, what do you do with it. If it is just "tweak" it, well that is just more subjective stuff. Can someone explain what to do with the special profile?
I'm not sure where the confusion lies? There's nothing mysterious really. ;D
For example, my purpose for making corrected colour profiles is to compare the original shot to a copy which has had the colour correction applied in order to to study & learn how a particular camera + lens + light + filter(if any) records colours. And also to attain reasonably accurate documentary colours for botanical work.
Keep in mind that setting an in-camera white balance or using auto WB with a particular camera + lens + light + filter is not always enough to provide correct colours (even though auto WB has improved immensely over time). If certain lenses or filters (polarizers come to mind) create colour casts, I want to know the direction and strength of such a colour cast (strong magenta? light cyan? blue desaturation? and so forth).
So you have to decide what you want from such a study. Does your camera + lens + light combo provide accurate colours without colour correction or not? Do you want to have accurate colours or do you want to keep a warm or cool colour cast for artistic reasons? If you want accurate, documentary colour, then you apply the colour-corrected profiles to any subsequent photos made with the profiled combination.
It is nice to know how a lens records. Also, with all the gazillion factors affecting colour perception, it is nice to at least be able to take one simple step towards accurate colour by creating colour corrected profiles. Production work for accurate colour goes many steps beyond this.
[I am assuming here that Lightroom works somewhat the same way as Photo Ninja with respect to creating these colour profiles. I do not know from my own experience. I hope what I'm saying is relevant to Lightroom.]
Added Later: Even with colour profiling using CC Passport, I note that some colours remain extremely difficult to reproduce well due to the constraints of colour spaces (and monitor viewing or printing, etc). I don't think I have ever been able to photograph violet or violet-blue flowers with complete accuracy. Some internal filters cut far too much violet. Even using a camera with the internal filtration removed, I still have trouble with violet colours.
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Andy, points well made. But colour profiling is all we have for a first step. I stop there and don't worry about ambient light and other factors because my documentary work is not currently being reproduced in printed form to be viewed in specific kinds of light. (oh well......)
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In addition to Andy's remarks I found an interesting piece to coonsiderate: http://www.redsharknews.com/production/item/2627-redshark-update-sekonic-c700r-and-measuring-colour-temperature-of-practical-lights
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The light I use for this kind of work is LED with a CRI of 95. That is supposed to the same an incandescent. Perhaps someone reading this has more information.
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The light I use for this kind of work is LED with a CRI of 95. That is supposed to the same an incandescent. Perhaps someone reading this has more information.
it has been my experience that many LED vendors offer claims for the color "accuracy" of their units that don't test out in actual use.
It'd be interesting, but not essential, to know the actual make and model of the LED unit involved.
By the way, CRI is a number that defines human perception of color. It is not a photographic specification.
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4) Not sure I understand the value of whitebalancing the existing images. Any potential color rendition difference of the lenses will be overlayed by software based assumptions the respective SW package will apply. But I might have missed the thinking behind this approach.
Good points Andy. I'd just like to expand on this last point since balance is affected by many factors:
1) The color of the subject being photographed - is it yellow, green, blue, warm, cold?
2) The color of ambient light falling on the subject - is it early morning light, mid-day, cloudy, sunny, tungsten lighting, LED, sodium, fluorescent ...?
3) Glass used in the lens (including filters) - some glasses transmit or absorb more strongly in some parts of the spectrum than others, which is why some lenses are warmer than others.
4) Lens coatings (including filters) - color balance of lenses can be affected by the coatings used. Nikon was well known for it's NIC (Nikon Integrated Coating) which integrated the coatings into the overall design, so there was a more consistent color balance across the entire lens lineup.
5) Filter stack in front of the sensor (points 3 and 4 above)
6) Spectral sensitivity of the sensor - Most sensors use Bayor RGRB pixel array, but the RGB filters used in one camera is not guaranteed to be the same as another camera. Eg one green filter may have higher efficiency in the green part of the spectrum, or greater transmission near the blue or red spectra.
7) White balance applied by the camera to the image.
8 ) White balance applied by any editing software.
9) White balance of the final viewing media - whether it is a monitor/profiling, or the paper/inks/dyes/pigments on a print.
10) Ambient light falling on the image (see point 2 above)
11) Color balance of glasses or contacts you wear (see points 3 and 4)
12) Color balance of your eyes - in my case one eye sees distinctly redder than the other!
13) How your brain interprets color, personal preference/bias - do you prefer green over blue, warm over cold...
The point I'm making is that there are so many factors which affect color balance, that I wonder about the the value of this exercise. The images in the original post are all quite acceptable in terms of color (if anything they all look a bit yellow/warm to me). The color casts of some lenses are warmer than others (all other factors being equal), but they are just one small factor in many, and none are "right" or "wrong". If any are not to your preference it is a simple job to adjust the color balance to your liking...
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The light I use for this kind of work is LED with a CRI of 95. That is supposed to the same an incandescent. Perhaps someone reading this has more information.
A spectral response curve actually measured by some trustworthy third party is required to judge the quality of light. Look at the link I posted above for example.
Worst light has strong peaks and large holes between the peaks like mecury vapour in the extreme and some monochromatic LEDs conmbined to a "white" source. 3 or 4 peaks do never make quality light.
Converter bulbs utilizing 5 or 6 bands smeared out by heat ... read: switch on 20 minutes before starting to shoot ... might have peaks, but they offer a significant amount of spectral response over the whole spectrum.
This allows very natural colors of skin and food e.g.
BUT: All of these sources are relatively dull. If you can deal with the 54,000 lumen of full spectrum you get from 1,000 Watts of power intake, you are mostly in the non-moving objects/subjects domain.
For models jumping through the studio you need serious studio flash batteries.
https://www.youtube.com/watch?v=vYwcKyBarzo
http://download.p4c.philips.com/lfb/f/fp-928045295081/fp-928045295081_pss_de_de_001.pdf
same goes for Osram Dulux L 954
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I agree that most likely the LED lights are a major factor in the issues you see Michael.
I recall the WB issues I saw when I started shooting the Nikon D1 - Yes the camera had a magenta cast in the firmware but the artificial and ambient light made me aware of digital issues.
Back then I used sometimes all of my lights, the images where unusable, I asked around and ended up with Elinchom, they are accurate both in color and power output and there is a huge amount of light modifiers available. I have a mix of battery powered and mono lights, no color issues at all.
I don't like their 'mount' but that's the only drawback.
Andrea - Super passport tutorial!!! Thanks ;)
I use it from time to time,,, fabrics can be so tiresome,,, ::)
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I agree with the observations regarding the LED light sources. A continuous light source is recommended. You can only measure light transmission in the parts of the spectrum in which you have light.
Michael, you could make a DNG profile with Adobe's DNG profile editor. You can then study and compare the color tables of different lenses to see which colors have a cast (relatively speaking, as you don't get the spectral transmission curve, but some info that relates to the color spaces and the corrections which are done within that space). It is important to lock down WB because the auto-correction is not always predictable. With Auto WB, it may very well be that lens color casts are being exaggerated.
I wonder whether one could in principle estimate the spectral transmission of a given lens from the color profiling data obtained from an image shot under a continuous light source with known spectrum...
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I agree that the use of Auto WB is, sometimes, asking for trouble. I shoot almost everything at daylight WB. The camera then acts as a reference to the light source, and informs me how the light source deviates from the theoretical perfect case.