Why Should I Care About a Little Color Shift?
The point here is to know the characteristics of your equipment so there will be no surprises. For example, if you know that your lights shift color quite a bit between min and max power, then you will be aware of this and try to avoid lighting setups where one light gets set at high power and another at low power. This isn't something one normally encounters, but I can see where it could happen. For example, one light in a large, double diffused softbox mixed with another light using an efficient reflector.
In addition to variance from min/max power, if you use lights of different vintage, and/or make, and/or model, it is possible that they emit a different color light in addition to shifting color over their power range. It never hurts to fully know your equipment.
What is a Typical Color Shift for Monolights?
A bit poking around on the web reveals that only some (few) manufactures publish this number. My data is published below. Please note that I am only looking at monolights, not power pack systems. A power pack system has the electronics in an external box called a power pack or generator, whereas monolights have all the electronics built into the light. Do not confuse the power pack with an external battery pack.
On the surface, it appears that typical is somewhere around +/- 200 - 300°K. However, this does not factor in the adjustment range. A light rated +/- 300°K over a 7-stop range is going to perform much better than a light rated at +/- 200°K over a 4-stop range. This may explain why some manufactures do not publish the numbers, it gets confusing.
Looking at the limited data I found, one thing becomes very clear. There are a few lights that are exceptionally good in terms of color stability. At the top of my list is the Paul C. Buf Einstein, having only +/- 50°K shift over an incredible 9-stop range! That is followed by the Photogenic Solaris with +/- 50°K shift over 6-stops and 100°K over 8-stops (I would be very happy with either of these). Honorable mention goes to Interfit with +/- 100°K over 5-stops for the low cost Stellar X and XD models.
Here is the data I found at the manufactures' websites.
I swore off doing another series, but am considering a short series on some of the photographer's tools. It will be the kind of information that could be useful to virtually anyone who uses a camera, beginner on up. Nothing technical, just a little attention to an often overlooked topic. So next time you come to Studiography, bring a friend along. :-)