technical: What film shall I use?
 

Colour or black and white?

Do you want colour or black and white prints? Do you want to process film and make prints yourself? Do you want something cheap and quick to put in a photo album or show to your friends? Or do you want all of the above?

Colour - advantages are that 35mm medium speed colour film is cheap to buy and easy to get processed in any high street around the world. But it is a time consuming and expensive process to do yourself, unless you are an expert.

Move the pointer over each layer of film to reveal what it is for (requires javascript compatible browser - full text available in printer friendly version

diagram: cross section of a colour film. Protective coating: this layer protcts the delicate emulsion. Although the surface can be cleaned with methylated spirits and a soft cloth, it is easy to scratch, crease or tear, so must be handled with great care. Any damage to this layer will make the negative unusable. Blue sensitive layer: layer sensitive to blue wavelengths, consists of an emulsion of silver halides together with colour couplers, compounds which help developer form a dye corresponding to the complementary colour.  In this case, yellow will be produced on the negative. Silver is removed from the film later during processing, leaving only the dye in the layers that make up up the colour image. Yellow filter: absorbs any blue wavelenghts that might pass through to other layers. Green sensitive layer: layer sensitive to green wavelengths, consists of an emulsion of silver halides together with colour couplers corresponding to the complementary colour.  In this case, magenta will be produced on the negative. Red sensitive layer: layer sensitive to red wavelengths, consists of an emulsion of silver halides together with colour couplers corresponding to the complementary colour.  In this case, cyan will be produced on the negative. Antihalation layer: this layer contains a dye which prevents light reflecting from the base of the film back into the image, so preventing blurring of highlights. Film base: the film base is a translucent ribon of cellulose acetate which holds all the other parts of the film together. It has to be strong enough not to tear in the camera and flexible enough to be wound tightly inside a film cassette.  It has an anti-curl agent to help prevent negatives curling up inside the enlarger.

Black and white - the advantages are that if you have access to a darkroom it is easy and relatively cheap to process film and make prints yourself. Great if you are a photographic artist, or a student of photography - but what if you haven't got time?

Black and white film using colour technology - the advantages are that this film, Ilford XP2, is a high quality black and white film with a unique structure that combines high speed sensitivity with fine grain. Instead of processing it yourself in the darkroom, it can go through a processing machine using the same C41 chemistry as ordinary colour films, and although the film costs more to buy, it costs the same as colour film for processing.

More about film and light

Most film you buy in the shops is known as Panchromatic, which means it is sensitive to all the colours of the visible spectrum. This applies to colour and black and white film, although film is slightly more sensitive to blue wavelengths than the human eye, which is why blue skies often look white in b&w photography. A yellow filter over the lens can be used to correct this. Colour film has its own built in yellow filter.

Orthochromatic film, on the other hand, is not sensitive to red and orange wavelengths and can be used under safe lighting for reprographic processes in black and white.

Infra red film is only sensitive to red and infra red wavelengths, some of which are not visible to the human eye. This produces a representation of the subject that is not usually visible, where colours and tones are distorted and changed. Black and white infra red film is fun to experiment with and can be processed in the same way as ordinary b&w film. A red filter over the lens is useful to filter out unwanted wavelengths.