RAW color calibration

We have a heat wave going in Seattle right now. Temps are in the low 90’s. Like most Seattlites, we don’t have air conditioning. The latest computer models for global warming predict that we’ll have wetter springs, but hotter summers. This is the precise track we appear to be on. I never remember seeing this kind of heat in June.

So I hid out in my cool basement, and ran calibrations on my two 5D bodies. There’s a nice protocol here on how to do this. There’s also some talk on the forums on how the 5D’s don’t process reds very well, with some ways to compensate in the Calibration tab in the Photoshop RAW converter.

I photographed a MacBeth Color Chart and ran the calibration protocol on both bodies. Both wanted a lot more red added to the calibration mix. Both subtracted a smidgeon of blue. Neither was much off the mark with the other. But they differed in the amount of green saturation to add: +30 on one body, +40 on another.

This also gave me an opportunity to check the metering with RAW capture. I used a gray card to set a proper exposure, but the resulting files needed a lot of correction in the curves before I could begin the calibration. I took out two manual meters to check, and they all came up with the same exposure reading. Only it was a third of a stop under when I read the numbers on screen. This confirms my intuitive experience of digital capture, where I had already gravitated to overexposing at least a third or more over no matter what.

When I apply this correction to a file, I’m not sure I like what I see however. Skin tones seem to go much redder than I’m used to. It’s like shooting with Velvia again. I reprofiled my monitor to make sure what I was seeing what accurate, and the print-outs show the same red shift on skin.

The numbers look good on the color chart. But I don’t typically photograph color charts for a living. I’ve nailed the craft part of the process, which in this case is seriously geeky. The art part is my input on what I think it should look like. If I choose to disobey the numbers, that’s my job.
                                                                                                                     Left: no adjustment under Calibrate tab. Right: compensation after Calibrate protocol

Comments

[Bruce Nall]

For what it is worth, I like the "no adjustment" portrait on the left - it looks more natural to me. My LaCie Blue IV monitor calibration apparently nearly matches yours as the MacBeth chart looks quite good. The red, green and blue are right on and the only chips that look slightly off are the magenta that looks a little on the cyan side and the yellow that looks a shade red. Maybe it is time for me to recalibrate!