What is the purpose of an orange filter that comes with Canon flash?

Question

My Canon (430EX III-RT) flash came with a neutral plastic diffuser and an orange plastic filter. Now, I understand the purpose of the neutral diffuser: it's (obviously) to diffuse the flash, without causing any color effects.

But I don't entirely understand the purpose of the orange plastic filter. It's transparent so it's not a diffuser. Apparently, it changes the color of the flash. But why would one want to do that? Is it for shooting in an environment where the lighting is based on incandescent light bulbs or CFLs / LEDs that emulate the color temperature (2700 K) of incandescent light bulbs?

Answer 1

Yes, this is for color matching. If you're mixing flash with ambient light from tungsten or some CFLs (often marketed as "soft" or "warm" white), you want to warm up the color temperature of your flash or it may look harsh and too... well, flashy.

From the B&H page for your flash:

Convert the color temperature of your Speedlite 430EX III-RT to match tungsten light sources with this SCF-E2 Color Filter from Canon...

included with the Speedlite 430EX III-RT.

Answer 2

One point of the flash is to either fill against a sun-lit scene or to actually create sort of a dusk atmosphere by overpowering the sun. The orange filter allows you to give a "golden hour" atmosphere rather than a "dusk" atmosphere. Here is an image where the orange flash filter would have given a more consistent result:

Edited by Rafa: I would say warmer instead of consistent. (Re-edit if you want)

Answer 3

The generic term for these filters is "CTO" (Color Temperature Orange). The main use is to match the color cast of the "flash" to the color cast of the "ambient" light (such as the sunlight during the golden-hour or indoor tungsten lighting or candle light photos). Doing this allows you to work around white-balance issues.

The flash natively has a "daylight" balance (nearly the same color as the sun at mid-day).

If the flash color isn't matched to the ambient light and the ambient light creates a strong color cast (yellow/orange) then as you "cool" the orange, you also "cool" the daylight-balance of the flash (causing it to appear blue). Fixing the color of one light creates a problem with the other light.

By matching the lights so they are approximately the same color, you can correctly white-balance the image. Sunset photos often should appear orange, but with the flash, the light wont look out-of-place.