Hi All, here is my two cents worth on this issue. I am a trained artist, and a professional photographer (retired) and everyone is forgetting these factors;
1) Colour temperature of the light in question. On a clear day, at noon, the colour temperature of the sky is about 20,000 degrees kelvin (20K) and to see this you need a color temp meter. If you were to photograph a vehicle, the sky imparts a colour (blue spectrum) to the colours of the vehicle. That is why, to the human eye, on these days, the colour of the vehicle appears slighly bluish. At sunset or sunrise the colour tempature drops and there is a pronounced shift to yellow through to red (+- 3500 to 4500 K). This explains the arguing over what is the shade of green that was used by the US during WWII on Sherman tanks.
2) The colour speed of the film you are using to photograph the vehicle. This is important (IE, ASA of Kodachorme slide film is 64) as some films impart a bluish tone (daylight) and some impart a redish-yellowish tone (ektachrome film ~ asa 100+) and this affects (effects) the outcome of the slide or neg.
3) The colour temp of the light you are working with, at home. ALL LIGHT BULBS have a colour temp reading of about 1800K to about 2000K (redish tone) and you need to correct this. Example: have you noticed that the colour of the german grey, is affected by the TYPE OF LIGHT it is seen under? It seems dark in your place you model (living room, etc) but UNDER DAYLIGHT, it now has a lighter, flatter shade. Same thing with other paints.
The manufacturers of the paints know this, and they correct the shades accordingly. But, it fails because of the factors above, and that is why there is endless discussion on what is the correct shade of green, black, tan, etc.
As a side note, I do not rely on any discussion in the various books that show pictures of (for example) WWII German tanks taken during the war, for these reasons;
1) The SPEED OF THE FILM. As I said above, film has a manufactured speed rating, that is used to set the light meters, that results in the proper exposure on the neg. During the war, the Germans used Agfa film that was rated about ASA 32 to 100 speed. No one, I mean NO ONE has taken in account the fact that during the war, in the later stages, developer may have been in short supply. What does this mean?
If you use developer that was exhausted (used too much) it now takes longer to develop the film, and if you don't take this into account, you UNDER DEVELOP the film, with the resulting pictures being flat with little detail in the shadows. If you OVER DEVELOP the film, you now have a contrasty, harsh neg, that you then have to UNDER DEVELOP the pictures.
Also if you over fix the film, you now have imparted a chemical shade to the negatives, that EFFECTS the resulting neg. And in all of this, AGAIN, NO ONE has thought of the fact that the SPEED of the paper that the picture is printed on, ALSO AFFECTS the resulting picture.
2) The exposure of the negative. I have used and owned Leicas, Nikons, Bolex 16mm Professional Motion Picture cameras and other makes too. It depends on the end use of the neg(I call all film neg's, even those that are slide film) that dictates the exposure i'd use.
My primary work was newspaper photography (Spot News) and I specialized in what is called "Push Processing". You need an understanding of Physics, and Logrithms to do this. Today, with digital cameras this is electronically done, but I prefer the old fashioned film cameras (better quality here!!) What I mean by push processing is the movement of the latent exposure, from one area of the log of the film, to another area, that results in a useable neg, that shows detail in both the highlights and the dark areas, without blocking up or reticulation occuring.
What I would do is to over expose the neg, and then slighly over process the neg, then UNDER EXPOSE (normal exposure on the charts) the processing of the picture as a print. This would result in a contrasty yet tonnality useable picture that would be acceptable on a printed newspaper, taking in to account the quality of the paper used by the newspaper (newsprint) as a product.
What I have seen from German sources from WWII, as the war progressed, the shortage of the paper the pictures were printed on, became accute, and they were forced to use the smaller (flatter tonnaly) or the larger (contrasty tonnaly) print paper that was most likely pre-war.
What is the paper and the negatives made from? A mix of chemicals that react to light (exposure) and the developer (it removes areas that are NOT EXPOSED). Silver Halide is the main chemical and you can see that in the late war pictures, the amount(s) of Silver Halide available started to decrease, as the pictures are flat, with NO detail in ether the highlights or the shadows.
This is a NEGLECTED AREA of modeling, as NO ONE UNTIL NOW has mentioned the affect and effect of light, colour tempature, type of film, and type of camera in the pictures we all use to model after. To be CORRECT, go and get a "McBeth Colour Checker" board and take a series of photographs of that tank, etc, and start with the correct exposure (assuming your ligh meter in the camera is correct ~ more on this below ...) and shoot a series of exposures from -2 stops to +2 stops, to see what I mean here.
About relying on your exposure meter in the camera, a word of WARNING HERE! Do NOT assume that your exposure meter in your camera is correct out of the box. I used to have my cameras checked on a routine basis, by NIKON CANADA ( I used Nikon F2AS, and F3, and F4's) and I also used routinely HASSELBLAD ELX's with 12, and 70 exposure backs and I had to have them CALIBRATED yearly, as they would go out, and read under by -+ 1 stop. Some cameras where better than others, and those cameras that were out by more than one stop, I would sell, to some un-suspecting Joe, as I could not rely on them. You cannot rely on the exposure meters without checking them, so it is worth spending $50 dollars ( a routine overhall of my Nikons would cost about $500 dollars, for each camera ~ well worth the money!) to about $100 dollars to make sure that your meter is working properly.
In the end, what is PLEASING to the person who make the model tank, aircraft, figure, etc, is what counts!
P.S. A word to the FSM Staff .... How about a short lesson in the Magazine, showing this above, how colour affects (effects!) the paint we modelers use on our subjects?? You could go and shoot a tank or something like that, and do the 2 stops over/under routine, to show the readers that are not trained in photography, what this looks like, and HOW IT AFFECTS the colour temp of paints (on the subject vehicle), etc. How about it FSM?
Rob Savage