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Filmmaking Dictionary: Number 8 / 85B Colour-Conversion Filter
Definition
An 85B filter is an amber colour-conversion filter with a nominal conversion from approximately 5500K daylight to 3200K. It warms the light reaching the camera and is traditionally associated with photographing daylight using an appropriately tungsten-balanced film.
Its effect is stronger than that of a standard 85 filter, whose nominal conversion is approximately 5500K to 3400K. Similar names do not make the two filters interchangeable. Follow the film manufacturer’s guidance and test the intended look.
What the Filter Changes
The 85B selectively reduces transmission to change colour balance. It does not make the scene itself warmer to people standing on set; the change occurs in the light passing through the camera’s optical path.
Every visible source is affected. A daylight window and a tungsten practical do not become independently neutral just because the filter is fitted. The filter shifts the combined scene, while the differences between its sources remain part of the photographic problem.
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Exposure Considerations
- Account for the filter’s transmission loss when setting exposure.
- A common Tiffen 85B specification is a factor of 1.6, approximately 0.6 stop.
- Check whether the metering system already includes the filter’s effect.
- Distinguish a plain 85B from a combination filter that also includes neutral density.
Practical Example
A filmmaker tests a tungsten-balanced stock for an exterior sequence. The test includes the recommended correction and an 85B comparison, with exposure properly adjusted for each. Reviewing skin, sky and wardrobe helps establish whether the stronger warming conversion suits the scene.
On a digital camera, changing white balance may produce the needed overall correction without placing an amber filter in front of the lens. Optical filtration can still be a deliberate choice, but it should be evaluated with the actual sensor and workflow rather than treated as mandatory daylight practice.
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Frequently Asked Questions
Should all 3200K film automatically use 85B outdoors?
No. Film manufacturers can recommend a particular filter grade for a specific stock. Use that guidance as the baseline instead of choosing from Kelvin values alone.
Is an 85B an ND filter?
No. Its purpose is colour conversion, although it reduces exposure. ND is intended to reduce light without deliberately making this warming shift.
Can the grade be changed later?
Yes, within the captured material’s limits, but post-production does not undo every exposure and spectral consequence of filtration.
Related Terms
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