Technical Information from The Photographers Centre

Filters for Colour Film

Colour filters are used with colour films either for colour correction or for special effects.

Correction filters
There are two types of correction filters.
Firstly there are those that allow you to correct the colour temperature of the light to that of the film used. The second group allow you to fine-tune your image towards warmer or colder results.

Creative filters
There are many special effect filters suitable for both colour and black & white work. Centre spot, multi-image, refractors, diffusers and starburst etc.

All filters have a factor number which tells you the amount of extra exposure needed to compensate for the lost of light through the filter. Cameras with Through The Lens metering will usually compensate for filters and no additional exposure will be required. Filter factors are not always the same on even on filters of the same colour: exposure increase indicated below should be treated as a guide only.

Filter	Colour	Exposure	Effect
UV	Clear	None	Cuts down the amount of ultra-violet light entering the lens. Good for protecting the lens.
Skylight	Straw	None	Reduces excessive blueness similar to UV but slightly stronger. Also good for protecting the lens.
80A	Blue	+2stops	For correct results in tungsten lighting with daylight film.
80B	Blue	+1¹/₂stops	For correct results in photoflood lighting with daylight film.
80C	Blue	+1 stop	For correct results with clear aluminium wire-filled flash bulbs using daylight film.
80D	Blue	+¹/₃stop	For correct results with clear zirconium wire-filled flash bulbs using daylight film.
82	Blue	+¹/₃stop	Correct colour with tungsten balanced 3200K film using 3100K lamps.
82A	Blue	+¹/₃stop	Correct colour with tungsten film using 3000K lamps.
82B	Blue	+²/₃stop	Correct colour with tungsten film using 2900K lamps.
82C	Blue	+²/stop	Correct colour with tungsten film using 2800K lamps.
81A	Amber	+¹/₃stop	81 series filters are generally used as warm-up correcting for too much blue light.
81B	Amber	+¹/₃stop	Stronger than 81A.
81C	Amber	+¹/₃stop	Stronger than 81B.
81D	Amber	+²/₃stop	Stronger than 81C.
81EF	Amber	+²/₃stop	Strongest of 81 series.
85A	Amber	+²/₃stop	Filter for type A artificial light balanced film in daylight.
85B	Amber	+²/₃stop	Filter to use tungsten-balanced film in daylight.
85C	Amber	+¹/₃stop	Filter to use tungsten-balanced film with clear zirconium wire-filled flash bulbs.
FLD	Pink	+2stops	Correction filter for using daylight film under daylight type fluorescent tubes.
FLW	Pink	+2stops	Correction filter for using daylight film under white fluorescent tubes.
FLB	Pink	+2stops	Correction filter for using tungsten balanced film under fluorescent tubes.
NDx4	x4	+2 stops	ND filters reduce only the amount of light.
NDx8	x8	+3 stops	ND filters reduce only the amount of light.

NDx4 reduces amount of light to a quarter and NDx8 to one eighth.

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