Paul C. Buff, Inc. Technical Forum

I noticed on the semi-circular flashtubes that some are 5600K and the other is 5200K. If I mix the two, I assume I get 5400K.

Seems as if I recall daylight used to be much cooler at 6000K and now I see my RAW files hovering around 5200K outdoors with the Nikon. Don't know if the blue sky has drifted to more red in the past 40 years from film era. I thought Gossen color temp. meters used 6000K as normal daylight back then?

Would a mix hurt at all? I have some older 5200K tubes that I bought for the old Ektachrome slide film (that had the bluish tint) but never used them. Just noticed one of my original WL 1200 Ultra tubes (5600K) is not firing. I put in the 5200K tube and it is firing well again. Things must be 20 years old by now and still working. I put the second 5200K tube in the other head to match.

The old 5600K tubes had a fine wire wrapped around the entire length of the tube. The 5200K ones do not, just the center portion is used (No fine wire over the entire tube.). The 5200K tubes have some thin gold paint on the inside curve of the tube.

Has daylight warmed up over the past 40 years and now 5200K is the norm?


Mack

"Daylight" is an ambiguous term, and always has been. It generally refers to the mid 5000K range, but different manufacturers will vary in what they call Daylight. Anywhere in that range is not technically incorrect, as daylight will change colors depending on the time and location, and by more than a couple of hundred degrees.

The difference in the two tubes is a UV coating. This coating is slightly yellow, and filters out UV light, and as a by product, will filter some of the blue, creating a yellower color. While it is possible to create a 5600K flash tube that is inherently UV coated, it is not always a simple matter. They gas formula and electrical properties of the flash unit will affect the color temperature as well as flash durations and other performance parameters. The Ultras were already tuned to that flash tube, so the coating was simply added. Lack of a UV coating can lead to a huge shift in color if the light hits a white fabric that has been treated with brighteners (some brands of softboxes, wedding dresses, etc).

The outer wire vs. inner metal strip is an iteration difference. The wire and the strip perform the same function.

As for averaging to 5400K, this would probably not happen, though we have not specifically tested this theory. We would expect it to still be nearer to 5600K.