What is the Films for colour photography?

Negative types. Color negative film has always been the biggest selling film type in the popular photography market; now there are companies who have started to discontinue a number of their films, particularly in the amateur ranges because of the popularity of digital cameras.

High street labs were geared up to process and print from colour negative film at competitive prices, now you will find a predominance of printers to create prints from your digital files. In terms of quality, however it is possible to get as good if not better digital prints from your home printer, although it might cost more per print. It is also possible to make black and white prints from colour negatives by either using silver halide material or

by scanning into and printing out from a computer.

Professional labs can also produce colour or monochrome slides. Colour negative films carry in effect three types of black and white emulsion, recording blue, green and red respectively. They reproduce the image in negative tones and complementary colours. To understand this term ‘complementary’ colour, remember the colour spectrum of white light. If you remove all the red wavelengths from the spectrum, what remains appears not white but greeny-blue (called ‘cyan’).

Cyan is therefore said to be complementary to red – opposite or negative to it in terms of coloured light. In the same way removing green from white light produces a purply-red (‘magenta’), and if you remove blue from white light you get a dominance of yellow. Cyan, magenta and yellow are said to be complementaries of red, green and blue light.

The way that natural image colors formed by your lens in the camera are turned into their complementary colors in the processed film. Each emulsion layer in the film also contains a colour coupler chemical – a yellow dye former in the blue-sensitive layer, a magenta former in the green-sensitive layer, and a cyan former in the red-sensitive layer. Couplers only turn into their designated colour dye when and where the silver halides to which they are attached are affected by light, and so develop to black silver. When towards the end of this chromogenic processing the silver is removed, what was originally the blue-sensitive layer contains an image in which all parts of the picture containing blue record as yellow.

Similarly, in other layers, parts of the image containing green record as magenta, and red parts as cyan. Wherever the scene was some other colour, the image is recorded in more than one layer, while white or grey records in all three. Viewed as one, the ‘stack’ of layers gives you the familiar colour negative image (plus a characteristic warm tint remaining in clear areas). Follow this through in the reproduction of the coloured pencils. During enlarging similar layers in colour paper give ‘a colour negative of a colour negative’, recreating subject colours and tones.