你知道不可見光是什麽?
Photographic film is a sheet of plastic (polyester, PET, nitrocellulose or cellulose acetate) coated with an emulsion containing light-sensitive silver halide salts (bonded by gelatin) with variable crystal sizes that determine the sensitivity, contrast and resolution of the film. When the emulsion is sufficiently exposed to light (or other forms of electromagnetic radiation such as X-rays), it forms a latent (invisible) image. Chemical processes can then be applied to the film to create a visible image, in a process called film developing.
link:
http://en.wikipedia.org/wiki/Photographic_film
真是丟任先眼沒個夠啊!
謝謝你送樂嗬!