Yep. That's a good general practice for keying. And it's hard to get beginners to do. I just recorded a beginner-level video training series for After Effects (finished yesterday!) and I made a point of showing how even an easy key requires two instances of the keying effect (in this case a special pass for the hair).
Well, we're so groomed to think that everything should be One Click Magic(TM)-which Ultra almost is--that that sort of mentality is to be expected!
I have noticed that, even with the dual effect (or maybe because of it), I get quite a bit of "shimmer" around the hair. Is this because of the "vector" nature of Ultra? Any way to counteract this without setting Choke so high that it carves into the foreground subject?
I don't have any experience with refining keys around hair with Ultra in Premiere Pro yet. I do all of my compositing work in After Effects. I'll try some things out and get back to you.
Thanks Todd. I just moved one of the clips into AE and used Keylight as a test; with just a scant amount of tweaking, I got a much better result than I could with Ultra. For shots featuring this particular individual, I think that that's what I'll have to do--poofy, wispy hair that's a nightmare to pull. Fortunately, after I set up the key once, it's a copy and paste job. I'll play more with Ultra to see if I can get a better result, but it's good to know that Keylight is there as my safety net--I'm glad that didn't get pulled when Ultra came along! I'd be happy to send a frame of this shot I'm working on, so you can see if you'll have better luck, if you like.
Now to diagnose why I'm getting weird purple edges when I use DL to send the alpha comp to Premiere... but that's another story.