CC filter recommendation
Picks the 80, 81, 82, or 85 series filter that matches your scene to your film.
Where to find it
Tools tab Color Temperature CC filter recommendation
Summary
Takes the metered scene Kelvin and the loaded film's color balance and produces a ranked list of recommended CC filters (cooling 80 series for tungsten on daylight stock, warming 81/85 series for daylight on tungsten stock, 82 series for mild cool nudges). Cross-references the calculator at 3.1.calc.
Detail
How it works
How the recommendation is made
The app converts both the scene Kelvin and the film's target Kelvin into mireds (1,000,000 divided by Kelvin), subtracts to get the shift you need, then ranks every CC filter by how close its mired shift gets you to that target. The closest filter is the top recommendation; the next three are ranked alternatives in case you don't have the first one in your bag.
Why mireds, not Kelvin
A given filter shifts every source by a fixed mired amount, but the Kelvin shift it produces depends on the source. An 80A is always a -131 mired shift, but on a 3200K bulb that drops you to about 2300K and on a 5500K daylight that drops you to about 4000K. Working in mireds keeps the math consistent and matches how filter manufacturers spec their filters.
Cooling versus warming
Negative mired shifts are cooling filters: the 80 series (80A, 80B, 80C, 80D) and the 82 series. Use these when the scene is warmer than your film expects, like tungsten light on daylight stock. Positive mired shifts are warming filters: the 81 series for mild warm-up and the 85 series for major warming, like daylight on tungsten stock.
Film balance choices
Pick Daylight for stocks calibrated to 5500K, Tungsten for stocks calibrated to 3200K, or Cool White Fluorescent for the 4200K reference. The recommendation flips entirely depending on which one you pick: a 4000K scene asks for a warming 81 on daylight film and a cooling 80 on tungsten film.
When the scene already matches
If the scene Kelvin lands within 10 mireds of the film balance the top entry is 'No filter, scene already matches film balance' followed by the closest three filters in case you want to nudge it anyway. This avoids recommending a near-zero filter just to fill the slot.