What is an 81A filter used for?

81A Filter: Purpose and Use

The 81A filter is a type of photographic filter that belongs to a group known as warming filters. These filters are designed to adjust the color temperature of the light that reaches the film or camera sensor.

Function and Purpose

The primary function of an 81A filter is to warm up the colors in a photograph. It achieves this by reducing the blue tones in the image, thereby shifting the color balance towards the red/yellow spectrum.

Applicable Scenarios

• Outdoor Photography: It is particularly useful in outdoor photography to correct the cool, bluish cast that can occur under open shade or overcast sky conditions.
• Cinematography: The 81A filter is also employed in cinematography to achieve a warmer color temperature without affecting the skin tones significantly.
• Film Photography: For film cameras, it helps balance the color temperature of daylight film when shooting in environments with a cooler light source.

Technical Details

An 81A filter typically has a mired shift value of about +18, which indicates its ability to change the color temperature. This shift makes lighting conditions warmer, often aiding in making a scene appear more inviting or lively.

It is important to note that with the advent of digital cameras with white balance settings, the necessity for warming filters like the 81A has diminished, as color temperature adjustments can now be made electronically. However, many photographers still use these filters for their unique effect on image aesthetics.