Generally you should select a film appropriate for the amount of light. Other considerations are the need to stop action or obtain a greater depth of field.
There are two basic film types, negative and transparency (slide/reversal). One of the advantages that most color and black and white negative film has is that the range of exposure latitude is far greater than that of slide film.
Black and white negative film has a greater degree of contrast latitude than both color film and transparency. Latitude in both color and black and white film is greater in overexposure, allowing as much as 2-3 stops, while still providing acceptable results. Color slide has much less latitude than most negative film, so you therefore must be more precise in your exposures. If anything slight under-exposure would be preferable to overexposing slide film. Color faults cannot be as easily fixed as with negative film, that’s why correct exposure is so important when shooting this film.
The advantages of slide film are the color saturation and the fine grain of the film. Making prints directly from slides can be an expensive proposition; one cheaper option is to have your slides digitally scanned and then printed from a CD. Look for a professional digital imaging lab such as Fuji who uses Fuji Frontier digital imaging equipment. The price of the scans will vary depending on how many dpi you require your image to be scanned at. The larger the dpi, the larger the enlargement possible.
The Film speed (ASA or ISO number) indicated the films sensitivity to light. The higher the number the higher the sensitivity to light. E.g. ISO 200 film is twice as sensitive to light as ISO 100 film. There are four speed categories into which films are placed. Low Speed Films are ISO 50 and under. These films are used outdoors on sunny days and have an exceptionally fine grain. Medium -Speed films ISO 64-200 work well on sunny and slightly overcast days and indoors with flash and also have a fine grain, ideal if fine detail is essential to your photograph. High Speed films ISO 250-640 work well both indoors and outdoors. Outdoors they allow you to use higher shutter speeds to freeze action and indoors they enable you to handhold your camera in dim lighting. They also work well with flash increasing the actual shooting range of the flash as well as providing a greater depth of field than slower films. On the downside a loss of definition and an increase in the grain size will be more obvious. Very High-Speed films ISO 800 -6400 are excellent choices for existing light photography, such as night sports, stage shows etc. These films are very grainy and may be useful in creating a very moody or gritty realistic atmosphere.
A couple of other points to consider when choosing a film are 1. If you are planning to make enlargements bigger than 10 x 1 5 slow to medium speed films will give you the best results. I.e. definition. 2 If you are planning to handhold a telephoto lens you will need a reasonably high shutter speed; at least one stopper higher than the focal length of the lens is recommended. In this case you may need a higher speed film, which will allow you to increase the shutter speed above the focal length of the lens.