Color Temperature of Flash Units

I have discovered quite noticable variances using color film depending on which

of my flash units I am using. I am using a living room couch with lots of

colors as a test subject. Flash units: Vivitar 283 and 2600, with and without

Lumiquest diffusers. Provia 100 and Reala 100 film.

The 283 produces more natural (to my eyes) colors. Especially with the

Lumiquest in place. The 2600 pictures are considerably bluer and colder

(without the Lumiquest; I will be testing it with the diffuser next). Same

camera/lens, of course.

I checked the specs. 283 is listed as 5500 degrees Kelvin.

2600 is listed as 6000 degrees Kelvin.

I realize that these are old units. Perhaps the color temperature has changed

over time, either the bulb itself, or the plastic cover.

Can a 500 degree difference really make a noticable difference? I don't have a

color temperature meter; that would be interesting!

I am wondering if anyone has noticed similar effects. And if so, have you

tried modifying the color temperature with a cc filter or whatever?

Anyone have a handy chart with a filter vs. color temperature values?

Someone recommended trying a Skylight filter with the 6000 degree unit. I may

try it.

I will appreciate your comments; thank you.

I cannot recall the source of information, but remember that 200 Kelvins variaton was allowed for tlash unit between full power flash and fractional power of the same flash. Variations between the same model flashes were allowed up to 300 Kelvins.

If one flash model is set for 5500 K, while another for 6000 K, yet another for 6500, you cannot really tell which flash is right or wrong, they are just different. That is why is important to use the same type of flashes in multiple flash setup, or else color problems can be noticeable.

You just try your flashes and see how that works for you. Differences in the light intensity, distance, etc, may mask out any color problem.

Perhaps the better approach is to gel the flash. The difference between 5500 and 6000K is about 15 mired (mired = 1 million divided by temperature), so something like 1/8th straw (20 mired) taped over the flash will correct the 6000K flash to close to the 5500K flash. The Cinegel swatchbook is a useful way to acquire a variety of flash gels:

http://www.rosco.com/us/filters/cinegel.asp

Gelling flash to be closer to the ambient light temperature can also produce a more natural look - but you may also need to filter the lens to produce a colour temperature that is closer to the film's natural balance, or to use a tungsten balanced film when lighting colour temperatures are low.

http://www.aeimages.com/learn/color-correction.html