Any accessory used while taking a photograph can enhance the final image; however, care must always be taken to ensure the images produced are effective.
One of the least expensive and yet most important of accessories is a filter.
Certain filters improve the colour saturation of the film or enhance the sky or quality of water.
Before deciding on any filter, indeed any accessory, test it in similar situations before using it for a specific shot.
Colour Correction Filters Some manufacturers' film may have a natural bias towards results that are too blue or green, giving an unwanted coldness to the photographs.
On the other hand, the film may be too warm and the results will then tend towards red or yellow.
To correct these tendencies there is a huge range of CC (colour correction) filters; for most photographers one or two colour balancing filters will prove more than adequate.
Polarizing Filters A polarizing filter is a useful accessory; not only will it enhance the quality of the blueness of a sky, making any clouds stand out with greater clarity, it can also be used to cut out unwanted reflections, such as those in shop windows or on shiny tabletops.
Exposure Compensation Since many filters cut down the amount of light passing through the lens, compensation in exposure must be made.
With cameras that have TTL meters this will be done automatically, but for manually operated cameras this must be taken into account before the final exposure is made.
This is quite easy as each filter comes with a number known as a filter factor which indicates the amount of compensation required for each exposure.
For instance a filter factor of 1 requires one stop increase in exposure.