Luminous Landscape Forum
Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: ErikKaffehr on March 04, 2015, 01:08:12 am
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Hi,
There has been a lot of discussion about CCD and CMOS. David Farkas made an experiment shooting the M9 and M(240)
The first part, he tries to match M(240) images to M9 under a set of conditions that favor the M9, it is here:
http://www.reddotforum.com/content/2015/02/the-great-debate-ccd-vs-cmos-part-1/
The next part he presents alternative images to see if viewers can identify the camera they have been shot with:
http://www.reddotforum.com/content/2015/02/the-great-debate-ccd-vs-cmos-part-2/
The third instalment will discuss the findings.
Best regards
Erik
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IMHO, evaluating image IQ based on internet images is a complete exercise in futility. ::)
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Hi,
I definitively agree regarding image quality, but it has been suggested that they would give very different colour, and that should be visible also at web size.
Best regards
Erik
IMHO, evaluating image IQ based on internet images is a complete exercise in futility. ::)
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I test I have done many times, and to me the results are always close. Where I still see a better look/feel with CCD tends not to be colors, but in areas like details on rocks, (lichen) finer tree limbs off in the distance etc. Whereas the CMOS always has a better shadow recovery.
Paul
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So in essence you're saying CCD IS better for fine detail photographic needs.
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David Farkas is a supernice guy.
Super humble.Soft spoken.Educated.
But NEVER neutral.
A Leica PR spokesperson.
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Yes,
I have noticed both. But in this case he compares Leica M9 to Leica M typ 240. Also, he just posts samples, even if those samples are processed. So it is a blind test.
Anyway, I would guess it is a good indication if there is an obvious difference between the two.
Best regards
Erik
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IMHO, evaluating image IQ based on internet images is a complete exercise in futility. ::)
Not only that, but there are many variables in the equation other than CCD vs CMOS. Older Kodak CCD sensor vs newer CMOSIS designed sensor made in a French fab. Different optical stacks, different Bayer filters, different microlenses, different electronics, and possibly different post processing. All CMOS sensors are not alike as shown by DXO's comparison (http://www.dxomark.com/Reviews/Canon-500D-T1i-vs.-Nikon-D5000) of a Nikon vs Canon sensor. They describe some of the variables within the same category of sensor (CMOS in this case).
Bill
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So in essence you're saying CCD IS better for fine detail photographic needs.
Phil
To be fair to CMOS, the largest I can compare is a D810 to say a 80MP CCD. The D810 and D800 with a good lens system can get very close if not the same degree of details. When I wrote that first comment, I was not considering that I was uprezing the D800 files to the size of the native 60 and 80MP shots. Uprezing always reduces finer details to my eyes.
A stitched D810 can do very well indeed.
What you tend to see is just a bit of difference in the rendering of the smaller details, CMOS vs CCD. I am sure that the new Canon 50Mp sensors with some of the new lenses that Canon has come out with will offer some excellent results.
Paul
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Hi Bill,
Absolutely agree with every word. But…
It is a wide spread conception with many photographers that CCDs have some magic property producing files that are superior. By that assumption viewers should be able to easily pick one type of camera over the other. If they cannot tell them apart it sort of indicates that the conception of CCD having superior colour to CMOS is a misconception.
Best regards
Erik
Not only that, but there are many variables in the equation other than CCD vs CMOS. Older Kodak CCD sensor vs newer CMOSIS designed sensor made in a French fab. Different optical stacks, different Bayer filters, different microlenses, different electronics, and possibly different post processing. All CMOS sensors are not alike as shown by DXO's comparison (http://www.dxomark.com/Reviews/Canon-500D-T1i-vs.-Nikon-D5000) of a Nikon vs Canon sensor. They describe some of the variables within the same category of sensor (CMOS in this case).
Bill
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Hi Bill,
Absolutely agree with every word. But…
It is a wide spread conception with many photographers that CCDs have some magic property producing files that are superior. By that assumption viewers should be able to easily pick one type of camera over the other. If they cannot tell them apart it sort of indicates that the conception of CCD having superior colour to CMOS is a misconception.
Best regards
Erik
Erik,
It has nothing to do with being superior. Some people simply tend to prefer one look over another look.
Likewise some people prefer the rendering of one lens, others the rendering of another lens. It does not necessarily mean that one is superior over the other either.
Although I have a lot of respect for David Farkas and the people from the Leica Miami store (I bought my S2 there) I am not sure what he is trying to prove with this test...
I personally have no doubt in my mind that through post you can make a CMOS file look like a CCD file. IMO that only proves that you have reasonable to good post skills...
But that's not the point...
The point is that some people still prefer the CCD files, Leica still sells about 350 M-E cameras (essentially an M9) per month and recently there was an online petition to keep the CCD Leica alive...
On eBay the M9 is still trending at $3,300. That's pretty good for a 6 year old digital camera...
Best, Joris.
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On eBay the M9 is still trending at $3,300. That's pretty good for a 6 year old digital camera...
Best, Joris.
Especially one that is odds on to need its sensor replacing. (regularly apparently until a "new" version is produced)
Disclaimer: Yes, at the makers cost but still ???
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Eric Fossum about the colours in this context: http://www.dpreview.com/forums/post/54028441 (http://www.dpreview.com/forums/post/54028441)
The context below is the actual CMOS/CCD devices in use in the relevant products.
The image sensor is nothing but a device which samples the image which the lens draws. If the optical stack on top of the sensor is similar, there is little to choose between the light of the image which hits the sensor surface and the optical stack has little to do with the underlaying sampling device technology. When it comes to sampling this light the modern CMOS sensors tend to do (much) more efficient job than the CCDs used in Leicas and the medium format cameras, and the lower the exposure, the greater the difference.
The preference of some to CCD over CMOS is not based on superiority of the former as it's long been inferior if we consider evidence objectively (e.g. DxOMark). They don't offer "better colour accuracy" or "sharper details", but lower signal to noise ratio (SNR) which, if anything, causes worse colour accuracy and less crisp details. Of course if one system has more pixels than the other more details may be sampled or larger sensor which improves SNR, but that's beside the point of CCD vs. CMOS.
The arguments on "different look" of CCD vs. CMOS is in my opinion somewhat absurd, as the "look" is defined by the processing of the signal (e.g. Lightroom, Capture One, Photoshop,...), not the image sensor technology as long as we're well withing the comfort zone of both technologies when it comes to SNR. Beyond that CMOS can do what CCD, but not the other way around.
Some people may well prefer CCD sensor in their cameras, but it's just psycology.
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Eric Fossum about the colours in this context: http://www.dpreview.com/forums/post/54028441 (http://www.dpreview.com/forums/post/54028441)
The context below is the actual CMOS/CCD devices in use in the relevant products.
The image sensor is nothing but a device which samples the image which the lens draws. If the optical stack on top of the sensor is similar, there is little to choose between the light of the image which hits the sensor surface and the optical stack has little to do with the underlaying sampling device technology. When it comes to sampling this light the modern CMOS sensors tend to do (much) more efficient job than the CCDs used in Leicas and the medium format cameras, and the lower the exposure, the greater the difference.
The preference of some to CCD over CMOS is not based on superiority of the former as it's long been inferior if we consider evidence objectively (e.g. DxOMark). They don't offer "better colour accuracy" or "sharper details", but lower signal to noise ratio (SNR) which, if anything, causes worse colour accuracy and less crisp details. Of course if one system has more pixels than the other more details may be sampled or larger sensor which improves SNR, but that's beside the point of CCD vs. CMOS.
The arguments on "different look" of CCD vs. CMOS is in my opinion somewhat absurd, as the "look" is defined by the processing of the signal (e.g. Lightroom, Capture One, Photoshop,...), not the image sensor technology as long as we're well withing the comfort zone of both technologies when it comes to SNR. Beyond that CMOS can do what CCD, but not the other way around.
Some people may well prefer CCD sensor in their cameras, but it's just psycology.
+1
It has been explained before, photons do not care about the sensor that records them. It's the sensor dimensions/filtration and post-processing that defines the 'look'. CMOS devices just produce lower read noise, and hence a higher S/N ratio which benefits low light exposures. CMOS devices also have a few other benefits like lower power consumption (good for the battery requirements) and thus they operate cooler, which helps to reduce dark current from spoiling long exposures.
Cheers,
Bart
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I can't really believe that there are still some people who argue about this issue in 2015. Without any doubt CMOS is absolutely much better than any CCD.
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It's the sensor dimensions/filtration and post-processing that defines the 'look'.
So basically what you are saying is that if people e.g. prefer M9 images over M240 images it is because of different processing rather than because of inherent sensor characteristics?
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It is a bit more complex:
The sensor just captures photons and converts to electron charges. Color is applied by a color filter grid array in front of the sensor. That is made by a chemical process and may differ between vendors. But, it has nothing to do with CCD or CMOS.
After exposure, raw processing comes into play. The image is now just numbers, but some numbers belong to red, blue or green pixels. Each position has one colour and lacks the other two. The missing to colours are interpolated from surrounding pixels. That is called demosaicing.
After demosaic we have assigned three color responses to each and every pixels. Now, the raw converter will use a "compromise matrix" to convert the color responses into an internal representation. Different profiles are thane applied to that internal colour response.
So there is quite a lot of math generating the final colours in each pixel.
Best regards
Erik
So basically what you are saying is that if people e.g. prefer M9 images over M240 images it is because of different processing rather than because of inherent sensor characteristics?
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So basically what you are saying is that if people e.g. prefer M9 images over M240 images it is because of different processing rather than because of inherent sensor characteristics?
Yes, although the Bayer CFA is made as a part of the sensor (similar on both CCD and CMOS), and they may well be different for the two sensors, requiring a bit different processing (which would also explain non-subjective differences).
Cheers,
Bart
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Yes, although the Bayer CFA is made as a part of the sensor (similar on both CCD and CMOS), and they may well be different for the two sensors, requiring a bit different processing (which would also explain non-subjective differences).
Cheers,
Bart
Interesting. Thanks for explaining!
One of the characteristics often assigned to the CCD look is that files are more film-like. A lot of CCD aficionados feel that CMOS files tend to look too smooth and too digital.
Would that be a consequence of the different processing? Or is the above-mentioned lower signal to noise ratio that makes CCD files look less smooth?
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Personally, I am pretty sure that is just a myth. Quite true, CCDs generally have more readout noise, but at least decent exposures at base ISO are dominated by shot noise, the natural variation of photons.
Another question is, what is film like. Like Velvia or like Tri-X?
One explanation may be that film has sort of a gradual roll off in the highlights. With digital sensors only the linear portion of the transmission curve is used. Now, it seems that MFD-s are doing a lot of effort to keep exposure from saturation on the sensor. Things like overrating ISO, conservative on camera displays and histograms. When using the default "film curve" Capture One seems to overexpose the image something like 1-1.5 EV. That can push down exposure a bit, thus increasing shot noise somewhat.
Best regards
Erik
Interesting. Thanks for explaining!
One of the characteristics often assigned to the CCD look is that files are more film-like. A lot of CCD aficionados feel that CMOS files tend to look too smooth and too digital.
Would that be a consequence of the different processing? Or is the above-mentioned lower signal to noise ratio that makes CCD files look less smooth?
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+1
It has been explained before, photons do not care about the sensor that records them. It's the sensor dimensions/filtration and post-processing that defines the 'look'. CMOS devices just produce lower read noise, and hence a higher S/N ratio which benefits low light exposures. CMOS devices also have a few other benefits like lower power consumption (good for the battery requirements) and thus they operate cooler, which helps to reduce dark current from spoiling long exposures.
Cheers,
Bart
+2
The CCD vs CMOS arguments came to the fore when MFDBs were exclusively CCD and the 135 format cameras were rapidly going over to CMOS. In addition to possessing an extra 6 stops of dynamic range the CCDs also had an inimitable advantage in image quality that only the cognoscenti (MFDB proponents) could perceive. It is almost akin to a religious experience and the Russel's Teapot (http://en.wikipedia.org/wiki/Russell%27s_teapot#The_burden_of_proof_argument) analogy could apply. Rather than having the majority prove that there is no difference, the burden of proof should be on the CCD proponents.
Bill
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I'd like to dilute this conversation with some RAW CCD vs CMOS files. Sorry, no Leica in my possession, only Sony a100 (CCD) & a850 (CMOS). a850 was shot in crop mode to yield a closer FOV. You can download files for evaluation from Google Drive (http://goo.gl/qqNLJu).
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Hi Malina,
Thanks for sharing.
Best regards
Erik
I'd like to dilute this conversation with some RAW CCD vs CMOS files. Sorry, no Leica in my possession, only Sony a100 (CCD) & a850 (CMOS). a850 was shot in crop mode to yield a closer FOV. You can download files for evaluation from Google Drive (http://goo.gl/qqNLJu).
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Rather than having the majority prove that there is no difference, the burden of proof should be on the CCD proponents.
Bill
I would suggest that those preferring CCD be allowed to do so by the majority. The conversion "force" would seem to me to come from the CMOS "camp". If just counting numbers CMOS has won by a handsome margin but doesn't seem to be happy until the "opposition" is willing to sign an unconditional surrender and hand in all their CCD "weapons", next they will want reparation for the time spent in forums bringing down the last few CCD adherents.
Disclaimer: I shoot both ???
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Personally, I am pretty sure that is just a myth.
Erik,
I am just saying what I am seeing and that is that CMOS files tend to look smoother and more digital to me...
BTW, this is an extract from the by you often quoted diglloyd dated March 2014:
DIGLLOYD: there are some things I miss about the M9 image quality; the M9/M9P CCD sensor has a look to it overall that seems more appealing than the M240 CMOS sensor, better acutance and a different look reminiscent of medium format sensors (the CCD that is). See also the comparisons of the two cameras made last year. In its favor, the M240 behaves better at higher ISO and also with the sun in the frame, and the EVF is a huge plus. There are other considerations too.
Please note that this discussion is not about superiority at all as some people here seem to believe...
For me film, CCD, CMOS, etc are different looks that all have their place. I would not classify one as being "superior" over another.
I am just trying to understand what I see and if the differences cannot be attributed to the sensors itself to what can they be attributed?
There was a recent GetDPI discussion on the same topic. Quoting part of that discussion:
Because the CCD/CMOS / Colour thing does not seem to be founded in fact (again, I'm not denying the difference in the colours). Colour is a function of the Bayer filter and the demosaicing (and partly the DR) - NOT a function of the underlying structure of the sensor. . . . . . . But the reason I referred to it as a 'religion' is that it isn't really possible to investigate on any kind of empirical basis.
Off shooting now with my CCD sensor :)
Thanks, Joris.
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Erik,
I am just saying what I am seeing and that is that CMOS files tend to look smoother and more digital to me...
That's because they have less noise at any given ISO. Less noise = smoother.
You can always add in more noise afterwards if you want.
DIGLLOYD: there are some things I miss about the M9 image quality; the M9/M9P CCD sensor has a look to it overall that seems more appealing than the M240 CMOS sensor, better acutance and a different look reminiscent of medium format sensors (the CCD that is). See also the comparisons of the two cameras made last year. In its favor, the M240 behaves better at higher ISO and also with the sun in the frame, and the EVF is a huge plus. There are other considerations too.
Please note that this discussion is not about superiority at all as some people here seem to believe...
For me film, CCD, CMOS, etc are different looks that all have their place. I would not classify one as being "superior" over another.
I am just trying to understand what I see and if the differences cannot be attributed to the sensors itself to what can they be attributed?
There was a recent GetDPI discussion on the same topic. Quoting part of that discussion:
Because the CCD/CMOS / Colour thing does not seem to be founded in fact (again, I'm not denying the difference in the colours). Colour is a function of the Bayer filter and the demosaicing (and partly the DR) - NOT a function of the underlying structure of the sensor. . . . . . . But the reason I referred to it as a 'religion' is that it isn't really possible to investigate on any kind of empirical basis.
Off shooting now with my CCD sensor :)
Thanks, Joris.
At the heart of it, a digital sensor is really just a counting device. Photons don't care what sort of device they're counted on. CMOS has a lower signal-to-noise ratio, so can count more accurately. The appearance of the image has nothing to do with the counting device at the core of it, but how light is modified before it gets to it - in other words, the Bayer filters, antialiasing and other filters that go in front and modify the light before it hits the photosites. These are different between CCD and CMOS sensors - not because they have to be, but because most CMOS sensors are designed to take greatest advantage of their high-ISO capability and give up colour accuracy and colour detail in order to further increase high-ISO capability. CCD sensors are crap at high-ISO, so no-one designs their filter stack to be able to shoot a little better at the top of their ISO range.
Put an image-quality-optimised filter stack in front of a CMOS sensor and it should give you the same colour detail and other characteristics associated with CCD sensors. By all accounts, that's what the low-ISO-optimised 5Ds is doing.
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That's because they have less noise at any given ISO. Less noise = smoother.
You can always add in more noise afterwards if you want.
At the heart of it, a digital sensor is really just a counting device. Photons don't care what sort of device they're counted on. CMOS has a lower signal-to-noise ratio, so can count more accurately. The appearance of the image has nothing to do with the counting device at the core of it, but how light is modified before it gets to it - in other words, the Bayer filters, antialiasing and other filters that go in front and modify the light before it hits the photosites. These are different between CCD and CMOS sensors - not because they have to be, but because most CMOS sensors are designed to take greatest advantage of their high-ISO capability and give up colour accuracy and colour detail in order to further increase high-ISO capability. CCD sensors are crap at high-ISO, so no-one designs their filter stack to be able to shoot a little better at the top of their ISO range.
Put an image-quality-optimised filter stack in front of a CMOS sensor and it should give you the same colour detail and other characteristics associated with CCD sensors. By all accounts, that's what the low-ISO-optimised 5Ds is doing.
Thanks for the clear explanation! Much appreciated!
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Hi,
Dave Farkas now published the third part of his test: http://www.reddotforum.com/content/2015/03/the-great-debate-ccd-vs-cmos-part-3/
Worth reading, I would say. I have just skimmed trough the article, as I am no potential Leica buyer.
He discusses how to achieve that Leica M9 look and gives a recipe for that. Reducing exposure, varmer white balance and some split toning as far as I recall.
The author seems to feel that most of the perceived difference is coming from the extended DR of the CMOS sensor.
He also writes that the Leica M9 makes very good images under the light conditions where it excels.
Best regards
Erik
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He also writes that the Leica M9 makes very good images under the light conditions where it excels.
Best regards
Erik
Much as: most lenses make very good images, if shot at f8 ;D
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Hi,
Yes, that is indeed true. I wouldn't argue with that.
Best regards
Erik
Much as: most lenses make very good images, if shot at f8 ;D
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+2
The CCD vs CMOS arguments came to the fore when MFDBs were exclusively CCD and the 135 format cameras were rapidly going over to CMOS. In addition to possessing an extra 6 stops of dynamic range the CCDs also had an inimitable advantage in image quality that only the cognoscenti (MFDB proponents) could perceive. It is almost akin to a religious experience and the Russel's Teapot (http://en.wikipedia.org/wiki/Russell%27s_teapot#The_burden_of_proof_argument) analogy could apply. Rather than having the majority prove that there is no difference, the burden of proof should be on the CCD proponents.
Bill
+3
Common hypes in MFDB:
a) CCD offers better dynamic range;
b) 16-bit offers superior image quality;
c) CCD offers better color/look etc.
I found these to be lies after I made my own comparisons. Indeed the Sony CMOS sensors can outrun any CCD sensors in most areas.
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Hi,
Dave Farkas now published the third part of his test: http://www.reddotforum.com/content/2015/03/the-great-debate-ccd-vs-cmos-part-3/
Worth reading, I would say. I have just skimmed trough the article, as I am no potential Leica buyer.
He discusses how to achieve that Leica M9 look and gives a recipe for that. Reducing exposure, varmer white balance and some split toning as far as I recall.
The author seems to feel that most of the perceived difference is coming from the extended DR of the CMOS sensor.
He also writes that the Leica M9 makes very good images under the light conditions where it excels.
Best regards
Erik
I just quickly checked the first 10 comparisons: by downloading the JPG images and pushing the shadow in ACR I got 80% accuracy - the CCD has a much noisier shadow even for JPG files posted on the web.
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Put an image-quality-optimised filter stack in front of a CMOS sensor and it should give you the same colour detail and other characteristics associated with CCD sensors. By all accounts, that's what the low-ISO-optimised 5Ds is doing.
I'm not an expert on sensor technology, but there are some differences between CCD and CMOS regarding blooming (http://www.researchgate.net/post/CCD_vs_CMOS_sensitivity_vs_anti-blooming_What_is_the_better_choice_for_DHM) and crosstalk (http://www.imagesensors.org/Past%20Workshops/1995%20Workshop/1995%20Papers/34%20Decker%20et%20al.pdf) as discussed in these links.
Perhaps some of the more technology savvy forum members could comment.
Bill
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I'm not an expert on sensor technology, but there are some differences between CCD and CMOS regarding blooming (http://www.researchgate.net/post/CCD_vs_CMOS_sensitivity_vs_anti-blooming_What_is_the_better_choice_for_DHM) and crosstalk (http://www.imagesensors.org/Past%20Workshops/1995%20Workshop/1995%20Papers/34%20Decker%20et%20al.pdf) as discussed in these links.
Perhaps some of the more technology savvy forum members could comment.
Bill
Yes, there are - I was simplifying it for the purposes of argument, since neither affect the colour and detail we were discussing (crosstalk reducing local contrast and bloom introducing artifacts). Both are less of an issue on CMOS.
Neither CMOS nor CCD record colour - they're mere photon-counters, with CMOS being a more accurate and less artifact-prone photon counter than CCD. Colour is entirely dependent on the filters in front of each photosite, which affect the amount of light hitting the photosite behind it, and the post-processing (both in-camera and out-of-camera), which takes the photon count from each photosite and, using the knowledge of what colour filter is in front of each photosite, uses these counts to generate an image.
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Yes, there are - I was simplifying it for the purposes of argument, since neither affect the colour and detail we were discussing (crosstalk reducing local contrast and bloom introducing artifacts). Both are less of an issue on CMOS.
Neither CMOS nor CCD record colour - they're mere photon-counters, with CMOS being a more accurate and less artifact-prone photon counter than CCD. Colour is entirely dependent on the filters in front of each photosite, which affect the amount of light hitting the photosite behind it, and the post-processing (both in-camera and out-of-camera), which takes the photon count from each photosite and, using the knowledge of what colour filter is in front of each photosite, uses these counts to generate an image.
From these considerations, it appears as if (contrary to CCD enthusiasts' assertions) that CMOS does have some advantages over CCD in addition to their lower read noise. As David Farkas' experiments show, the differences are subtle. However, in his comparing the two cameras, there are other non-controlled variables than sensor type. Certainly, CCD has been abandoned for 135 type sensors, and the advantages of CMOS are being exploited by MFDB vendors when that technology is available for a given sensor size.
Bill
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Hi,
Your observation pretty much agrees with Dave Farkas's evaluation.
Best regards
Erik
I use both CCD and CMOS Leica M series cameras. The difference I see between the two is that the M9 delivers a slightly punchier file out of camera which is probably down to the difference in dynamic range rather than sensor type. Colour reproduction can vary slightly between the two cameras. My workhorse camera is the M240.
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Hi Keith,
At the end of this article: http://www.reddotforum.com/content/2015/03/the-great-debate-ccd-vs-cmos-part-3/
Best regards
Erik
Hi Erik, have you a link to David Farkas's evaluation?
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Hi,
Just to say, the outcome was pretty much what I would have expected. Some of Dave Farkas's observations were interesting, like the M240 sensor having better highlight roll of and the wider dynamic range causing less contrasty image. Those differences may have a lot to do with camera profiles.
I own both CCD and CMOS, in my case a P45+ having CCD and a few Sony cameras with CMOS. I did some pretty careful comparison between the P45+ and the Sony Alpha 99, and found that both were pretty accurate when using an IT8 test target.
Would someone be interested, here is a draft of an Article I planned on writing for OnLandscape: http://echophoto.dnsalias.net/ekr/Articles/OLS_OnColor/OnColor.pdf
Best regards
Erik
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here is a draft of an Article I planned on writing for OnLandscape: http://echophoto.dnsalias.net/ekr/Articles/OLS_OnColor/OnColor.pdf
Excellent comparison Erik. It is interesting to note that the simple Sensitivity Metamerism Index (ISO 17321 - where the SLT99 appears to be substantially better than the P45+) is not representative of your more complex testing.
Jack
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Jack,
Thanks for commenting.
One issue with my test based on the IT-8 is that the dyes used in that target are based on the chromogenic process and I guess that they are intended to minimise metameric error.
To me it seems that colour profiles play a very important role in colour reproduction. The enclosed samples shows six different conversion of the same subject. In this case I actually measured the spectrum on the blades and the leafs, spectrum based representations are also included. The purplish blue (I think it is called) colour was reproduced as blue with Capture One 8 on both P45+ and Sony Alpha 99. It may be hard to know what a natural representation is.
Best regards
Erik
Excellent comparison Erik. It is interesting to note that the simple Sensitivity Metamerism Index (ISO 17321 - where the SLT99 appears to be substantially better than the P45+) is not representative of your more complex testing.
Jack