Sixticolor measures off - still useable?

[John Rodriguez]

I picked up a Gossen Sixticolor. I measured it on my light-table and was getting 4500 instead of 5000k. Then I put my Eye One Display 2 on it in color temp reading mode and got 5000k. Can I assume that it will always read 500k warm or is it's response logarithmic, in which case the temperature variation would increase in one direction?

[Brian C. Miller]

Test it with actual daylight. I have one, and it seems to be pretty much spot-on. Two light sources really aren't enough data points to say if the meter is off or not.

[Mark Woods]

It doesn't really matter. Once you shoot tests with your meter and decide the look you like, then use the CT that you had when you did the shot. If you read AA's negative and zone system tests you'll see that even meters and shutters that are off can be calibrated.

[Leigh]

Then I put my Eye One Display 2 on it in color temp reading mode and got 5000k.

I think you're comparing two different generations of equipment and different technologies.

The actual definition of "Color Temperature" is just the ratio of red to blue.
It knows nothing about green at all. This is the standard used by the Sixticolor AFAIK.

The filters in the meter may not be excluding the green light from the fluorescent bulbs on the light table.

The Eye One would certainly have sharp-cutting filters since it does measure the green portion of the spectrum.

Try comparing readings of a halogen bulb rather than fluorescents. They don't have the excess-green problem.

As others have suggested, shoot with it and calibrate it to your results.

- Leigh

[Jim Jones]

Make sure the opal glass over the cell of the Sixticolor is clean and unobstructed when using it. The meter uses side-by-side areas of the cell for measuring red and blue light.