Using a DSLR to measure color temperature

[Pieter12]

A recent discussion about LED lights used to inspect prints led me to a thought: could I use a DSLR (Nikon D4) on auto white balance to measure the color temperature of my darkroom print-viewing area? I believe so. After making a number of bracketed exposures, I looked at the raw files in Photoshop, and they all read 4100º. I also have a graphic arts viewing box that uses daylight-balanced fluorescent tubes. Next step is to use the D4 to measure that.

 

[Mr Bill]

You probably could; you'll be getting a "correlated color temperature," CCT, meaning how it looks to the human eye with a neutral reflector.

Something to keep in mind is that this doesn't prove that the lamps are suitable for color print inspection - you could do the same test, for example, with eco-friendly fluorescent lamps such as compact fluorescent (CFL) which are pretty horrible for color print evaluation.

Something that I've occasionally done is to use a DSLR camera to shoot a white card, then look at a color histogram. I can manually change the camera's white balance by setting a color temperature. When I find a setting where the three color spikes line up then that is a good approximation of the CCT.