While I was at HTL I has the opportunity to work with Bill Ingalls, who is an outstanding portrait photographer. He showed us the setup that he uses for headshots, and let us work with it for a while. The other photographer that was working with Bill at that time was Eric Aschen, who had a Photovision calibration target. I've seen folks advocate this before, but I had never used one, and wasn't willing to drop $60-100 just to try it out. Fortunately, Eric had one of the targets and let me take a turn with it. Here's what I learned.
In short: it's cool, and I want one
Before I played with the target, I took this shot. I metered the light with my handheld incident light meter, and grabbed the exposure on the left. In post-processing, I adjusted the levels to get what you see on the right. As you can see, the original shot was a bit flat, but a "quick" levels adjustment brought the image to life. I'm pretty happy with the final exposure, but I basically had to "play" with the levels adjustment till I was happy. There was no clear way to make sure I had it right.
Now onto the target... The first thing you do is put the calibration target in front of the subject's face; in this case, the charming Julianna.
On the left, you see my original exposure. This is the "proper" exposure because the histogram is centered, not truncating either the highlights or shadows. On the right, you see what the image looks like after I loaded it into my photo editor and adjusted the levels. This levels adjustment was easier, and feels better because you have very clear "spikes" with which to work. I made this levels adjustment as an adjustment layer, to make workflow easier.
Then this is the next exposure I made. You can see that the original image is similarly muddy to the shot I took with the incident light reading. Incidentally (no pun intended), both my light meter and the Photovision target told me to shoot at f/11. I think the very minor difference in the two original exposures is due to the fact that I changed lenses, but I suppose it could also be small differences in strobe output or subject positioning. But I digress... So I simply coppied the adjustment layer from the calibration target over to this layer, and you see the results on the right. I think this is every bit as good as the result I got by "playing" with the levels on the first shot...maybe even better...and it was much simpler.
So in the end, I was pretty impressed with the target. I know you're supposed to be able to use it for white balancing, but I didn't test that feature...as I didn't know I was going to be able to do this till after I had already set my white balance, and honestly it didn't occur to me to fix what weren't broke.
I'm going to put this target on my photo wish list, and will likely pick one up soon. They come in sizes ranging from 6" to 32" (Eric had a 14"), and are probably a good investment for any studio photographer.
Thanks for letting me play with your target, Eric!
PS There are some propaganda videos on their website, but I haven't had a chance to watch them yet.