Basing colour definition on reproduced photos, B&W or colour, can be a minefield, especially if the viewer does not have an understanding of the photographic materials and processes of the period concerned, and what is involved in the various stages of reproduction to print in a publication.
The variables in these processes are many and, without some form of training in the subject, reaching a positive conclusion is virtually impossible. Even with training, a definitive answer can only be a 'best guess'.
For example, a colour reversal film (a transparency or 'slide' film), has as its basis a B&W negative emulsion, along with 30+ 'layers' of colour additives, colour dyes, colour couplers and stabilisers.
Given that the first stage in producing the image is correct, that is, the initial exposure, then the latent image
should be as close as possible in colour rendition and contrast, to the actual subject.
However, it will now already be apparent that the first set of variables are now in play, with exposure affected by aperture and shutter speed, ASA / ISO setting' length of exposure and, of course, angle, quality and 'colour tempertaure of the light source (mainly daylight in the case of this discussion).
The time between exposure and processing, along with variations in temperature during storage before processing, will also effect the final result.
Then there is the processing itself - this has to be absolutely perfect if the optimum results are to be obtained, with process control monitoring taking place at least three times per day, and with the correct temperatures (plus or minus 0..25 of a degree), time, agitation and chemical replenishment of the Developer, Bleach and Fix.
Any and all variation in this process will effect the final colour balance and contrast.
If the now processed colour transparency is to be printed, then (at the period of WW2) an inter-negative has to be produced. This is a colour negative, exposed from the original, which is then used to produce a colour print, just as a colour negative would be used to do the same.
The same variables now come into play - exposure, filtration, and processing.
When this colour print is to be used for reproduction in a printed publication, then four B&W negatives are produced, as colour separations, to then produce four printing plates covering Cyan, Magenta, Yellow and what is generally known as a 'black printer', the latter providing the overall contrast to the final printed page.
This process, of course, is wide open to a multitude of variables, and without extremely rigid process control, the finished image can end up looking nothing like the original, in terms of overall colour balance, and / or contrast.
Although perhaps not quite as complex as colour reproduction, the processing, printing and reproduction of a B&W image still has many variables, starting at the camera and then, like the colour image, involving processing of the film, exposure onto the b&W paper (where the choice of paper 'grade' can make a vast difference too), processing of the final print, and then the variables of reproduction, via a half tone negative and printing plates, to the final printed page. And this is not even allowing for any filters that may have been used over the camera lens, and is accepting that the correct type of B&W film had been used in the first place !
From this, it can be seen that some knowledge of the photographic and printing processes is required to even begin to interpret and assess colour tones and hues in reproduced images. I am fortunate in that I had rather extensive training in this field, but that does not mean that I could give an absolutely definitive answer to what colour is what - although there's a very good chance I could decide between what is grey, blue, green etc.
So, basing definite opinions on rather dubious colour (or B&W) reproductions, without knowing, or at least understanding, the history of the image in question, it's method of reproduction, whether it's original or copy etc, and without some grounding in photographic and printing sciences is, at best, a very 'hit and miss' affair.
Suffice to say that, what we know, or accept, as RLM 02
was used as a camouflage colour in 1940, with records from crashed aircraft to support this, although I'll return to this later.
There is also evidence to support the use of greys, which might or might not have been 'official' RLM colours (it is generally considered that these were locally mixed paints), and there is also evidence that one Geschwader, JG53, used various colours, in a number of different patterns not at all related to the 'official' patterns.
The colour we know as, or at least call, RLM 02 was still in use in early 1941, both on the BF109E and BF109F, and on the FW190, and was then replaced by the three greys, RLM 74/75/76, which became fully in use by summer of that year.
Even Rolf Pingel's BF109F, the first of it's type to be brought down intact, on 10th July 1941, was described, in the crash report, as being painted "..dark olive green on the upper surfaces", with pale blue sides and under surfaces, although the B&W photos of this aircraft (and there were many), distinctly show the common splinter pattern associated with the BoB period 'Emil's', and a tonal reproduction which suggests RLM 71/02 upper surfaces.
Now, returning to the actual
shade of what we call RLM 02.
As I mentioned in a previous response, I have long had doubts about the shade currently offered by most model paint manufacturers, as I believe that this 'current' shade is too light, compared to the colour used as an upper surface camouflage, for the reasons previously stated, including a distinct difference in tonal reproduction, when compared to the 'real' RLM 02, seen on undercart legs, cockpits etc, in contemporary photos, B&W and colour.
I still believe that the actual shade used was slightly darker, the same as the original model paints offered by Humbrol, Compucolour and others, in the late 1970's and early 1980's, and close to the shade I now mix for my models, as previously illustrated.
Now whether this really
was RLM 02, or a variation in shade of this paint, I don't know, and it
could be that modellers and historians have been referring to this as such, incorrectly, for decades.
Whatever the reason, what we now refer to as RLM 02, either in its 'true' form, or slightly darker, was used in 1940, and was distinctly different from the previous greens, and the later greys, although it was a greyish-green hue.
To offer a comparison of the the two schemes, that is RLM71 and RLM 02, and the later RLM74/75/76, below are B&W photos of two of my models, showing both schemes, and the tonal reproduction differences are clearly evident.