Date: 17 Mar 2006 19:16:50 -0000 Subject: SMML Vol 3101 The Ship Modelling Mailing List (SMML) is proudly sponsored by SANDLE http//sandlehobbies.com For infomation on how to Post to SMML and Unsubscribe from SMML http//smmlonline.com/aboutsmml/rules.html ---------------------------------------------------------------------------- MODELLERS INDEX 1: Re: USN S-Class Sub Colors - Philippines - December 8, 1941 ??? ---------------------------------------------------------------------------- MODELLERS ---------------------------------------------------------------------------- 1) From "Harold Stockton" Subject Re: USN S-Class Sub Colors - Philippines - December 8, 1941 ??? John Snyder is completely correct in pointing out the differences between the two colors being different because of the more fuller explanation of the base colors used between the two grays. One being toward the purple-blue and the other more toward the more true blue end of the color spectrum. And a small point should be made of John's mention of the use of orthochromatic film. It seems that orthochromatic films are very suspect as far as color interpretation due to their blindness to reds, orthochromatic films will often record yellows as almost black, and known reds too. Orthochromatic films are sensitive to greens, blue and violet light, and this is why "the original Standard Navy Gray (a) appears almost white.", because it was in the Purple-Blue (PB) end of the spectrum. With ortho film's use in the photo of the USS Sapelo (AO-22), the purple (toward the red shift) would have been completely lost, and the blue of the "the original Standard Navy Gray (a) appears almost white.", because the blue would have reflected more light, shifting it even further toward the lighter end of the scale. However, this type of film does have some benefits over panchromatic films in that Orthochromatic film is a Black and White film that is color sensitive to the blue end of the spectrum, reaching the wavelength which produces green light, but not red. "ORTHOCHROMATIC Orthochromatic films are sensitive to ultraviolet [UV] radiation, violet, blue, and green light. The emulsion provides approximately correct reproductions of blue and green objects in corresponding tones of grey in daylight or tungsten light. Used primarily for copy work and graphic arts photography, orthochromatic film trade names usually contain the word "ortho." Ortho-type films may be used as continuous-tone or halftone (line) film. "PANCHROMATIC Panchromatic films are sensitive to UV radiation, violet, blue, green, and red light. Panchromatic films are used for copy work, portraiture, and general photography. These films have only one ISO speed." http//www.tpub.com/content/draftsman/14263/css/14263_383.htm And from all of this we can see that if we know the Measure or date of a photograph, we can then compensate for the lightening effects that orthochromatic film seems to have when it looks like the "the original Standard Navy Gray (a) appears almost white.", especially when it looks as if this color is being highlighted by a very low and strong sunlight effect. Harold Stockton > Nice post from Harold. I want to add a couple of caveats, however > > "Though no actual paint chips of these colors existed when the Floating > Drydock book was published, they did note that the 1937 handbook mentioned > above did give their respective PB numbers, and which allows anyone to refer > to the MUNSELL BOOK OF COLOR to readily discover the exact percentage of > purple-blue (PB) to gray (chroma." > > That is only true if you refer to the 1929 Munsell Book of Color, and NOT to > the present Munsell Book of Color. > > "A good example of this can be seen of the USS Sapelo (AO-22) that is being > given a new coat of Measure 1 Dark Gray (5-D) at Norfolk Navy Yard in March > 1941. A photo of this can be found of page three (3) of the 1976 CAMOUFLAGE > book. Because of the very bright light conditions present from the angle > that the photo is taken, the original Standard Navy Gray (a) appears almost > white, while the Dark Gray (5-D) appears as a very dark gray." > > The #5 Standard Navy Gray appears almost white chiefly because the original > photo was made on orthochromatic film, which is blue-sensitive and renders > anything blue as near-white in the final print. The Munsell notation for #5 > Standard Navy Gray was 10B 6.5/1.5, meaning it was a blue (of low chroma), > and thus rendered nearly white by the ortho film. > > It is also worth noting that, despite what the Floating Drydock camo book > may say, #5 Standard Navy Gray and the 1941 version of 5-L Light Gray were > NOT the same color 5-L Light Gray had a Munsell notation of 10B 7/1.5. ---------------------------------------------------------------------------- Check out the SMML site for the List Rules, Reviews, Articles, Backissues, Member's models & Reference Pictures at http//smmlonline.com ---------------------------------------------------------------------------- End of Volume