5Delicious
New member
What your post tells me, is that I really do have to invest in a good light meter so I can measure things for myself and go from there... I guess the expenses never end![]()
Oh, and btw if you have a DSLR, you already have a great light meter. Canon's auto white balance is particularly good, and will adjust not only cool/warm, but also dial out green/magenta spikes with ease. In fact, if you only ever set your camera to Auto White Balance, and you're only using one kind of LED, you may not even notice the green cast because the camera will dial it out.
Here's a quick and dirty method to use AWB to test for green spike. Set the camera up in live view mode, and while looking at the LCD, simply switch between Kelvin and auto while dialing the Kelvin temperature to the closest possible match. If you find a Kelvin temperature setting where the color on the screen does not change at all between auto and Kelvin, then congrats -- your light requires no correction.
On the other hand, if you can get close, but there always seems to be a shift of some sort, that is because the camera is making settings along the green/magenta axis that your manual Kelvin setting cannot account for. If this happens, grab a sheet of 1/8 magenta and drape it over the lights and do the test again. If there's a still a shift, try 1/4. And so on. You will quickly find the spot where there's no shift, and your lights will be balanced. As balanced as they can be, anyway!
Finally, if you take a test still, there's actually a truckload of color metering information hidden in the exif data that most image editing applications simply do not display. Here's a sample (attached). You have all kinds of cool details on what color temperature the camera measured versus what it actually selected, what picture style and settings were used, and so on. This data was output by the OS X droplets listed here:
http://www.sno.phy.queensu.ca/~phil/exiftool/
You just drag your .jpg onto the droplet and up pops a text document with all the details. Awesome tool...