Tiffen 52mm 81B Filter

Size:52mm Product description Warming filters reduce excess blue tones that effect daylight film when shooting sky or sea scenes or in high altitude photography. They are also effective if your flash exposures are too 'cool'. 'B'is slightlty warmer than 'A' but has the same filter factor of 1.4, requiring 1/2 f-stop of additional light. All light sources, natural or artifical, have characteristics that affect color rendition on film. Color correcting filters are designed to 'warm', 'cool' and/or correct for the many variations of lighting you might encounter. All filters have a 'filter factor' which is a measurement of the light it absorbes. Cameras with internal metering (through the lens) will automaticly adjust the exposure. Amazon.com Useful with daylight-corrected film in cool-light conditions.