Monday, January 02, 2012

Panchromatic film

Early photographic film (plates) was pretty much only sensitive to blue light. Then came orthochromatic ("correct colors") film, which expanded into green light, but still had very little sensitivity to red light. This is why skies are often white in early photographs (or graduated, because it was corrected in the darkroom), blue colors were over-exposed compared to reddish colors.

Panchromatic film, much closer to our eye's perception because it included sensitivity to red, gradually won over in the early 20th century, although it was more expensive and harder to work with, for example you could no longer use a red light in the darkroom, it had to be actually dark. (B/W photo paper for prints is still red-insentive, so you can use a red light to navigate by.)

(White sky example, photo taken on an orthochromatic plate in 1906. Bigger picture on click. An even bigger one can be found on Shorpy's.)

No comments: