Which filter to match Flash to 2700k LED ambient light

Quick question,

I am shooting an event in a room that uses LED lighting for ambient light. They use GE LED20/D/P38V/827/40 bulbs which are a 2700k temp light.

I would like to match my on camera flash to these lights the best I can. any recommendations on the filter I should put on my flash? (Canon 430ex II)

I think it should be a full CTO, which I think matches 2900k, but I can't recall.

Any suggestions?

Thanks
Doug

Full CTO is technically the proper filter, but I'd probably use a 1/2 to 3/4 so the strobe is just a but cooler. That will help pop the subject out of the background a bit. Also, ensures that the room looks warm.

Thanks Dave,

good point, a 3/4 will probably save my 1/3stop of light was well over a Full CTO.

Keep in mind that CTO really converts 5500K to 2900K, so the CTO would leave your flash just a touch cool compared to your GE LEDs

3/4 should get close to 3200K which is probably about right.

There is a mired shift calculator here
If you gel the flash (assuming ca 5500K) to match your LED you could use a Lee 285 + 206 on your flash, then WB your camera for the 2700K.

J Michael wrote in post #16788806
There is a mired shift calculator here
If you gel the flash (assuming ca 5500K) to match your LED you could use a Lee 285 + 206 on your flash, then WB your camera for the 2700K.

This is a very good tool.
It reminds me of the detailed filter packs we would create for our color critical clients when shooting film. Buy the film by the case, arrange for lab to process everything with neutral chemicals, and also buy photofloods by the case for consistent color lighting.

All that because once the film was exposed and processed, the only way left to color correct was in pre-press and that could add significantly to separation costs for a catalog.

Today we have the white balance eye dropper, DNG profile editor, color checker charts.

For an event, unless its for a dress designer that is paying lots to get perfect color rendition on their garments, 1/2 to 3/4 CTO and go.

The ability to wb in post is great, no question. However that isn't much help when you have sources of unequal color temp. In that case you run the risk of having to balance for one source and letting the color of areas lit only by the other source fall where it may. You can possibly have areas lit only by source A, areas lit only by source B, and areas lit by sources A+B, all with different color temp. If the color difference is minimal as David alludes, then probably not an issue depending on the requirements for the assignment and your minimum standards. You might also check and see if a swatch sample from the filter swatch book is large enough to cover your flash.

If there are more than two light sources with different color temps then its nearly impossible to get them all together into a common color temp with out putting correction filters on all but one source bringing them to that master.

Most often in reception venues there are 3 to 5 different sources. The case here is, apparently just a second source. That makes it much easier.

When doing color critical work, its much preferred to be able to have a single source and then control it.

Thanks all for the input.

Luckily it is a small room (750sq feet). Lit overhead with the same LED bulbs in each socket. The light overlap seems pretty good, and there are no other light sources in the room (windows etc).

I also white balance with a ColorChecker Passport, and will be shooting in RAW, so as long as I am close to a match with one of the gels I should be good. I suspect either gels will be better than shooting full mixed light with no gel.

So think I will bring along a 3/4 and a Full CTO, test each for color mix, and go with the one that give the best overall look