Mine says nothing about using a mirror (or incantation) just hand tighten the lugs until you can't get them tighter (with your fingers not with a drum key) then place the drum dial about one inch from the rim and tighten to the suggested tension, then go to the lug on the opposite side and do the same, keep doing that on a star pattern until you get all the lugs at the same number (same tension). You have to check the lugs a few times because the tensions change but eventually they will all be the same. Then flip the drum and repeat for the suggested number on the resonant head. sometimes they are the same, sometimes they are different. Just do that and you should be able to tune your drums in no time. later on if you want to get more technical you can tune to pitch using a more better tuner such as the Tune Bot ... I don't need it so you might not either.
I tried my Tension Watch last night. (Happy report)
The mirror thing in the instructions was to calibrate the device. I didn't go that route, so I just noted how far off 0 it was to start, and allowed for that when I used it. No incantations necessary.
While I had a little more time than i usually do, I till didn't have enough time to really dig deep while using it. Still, I was very impressed. I did the most basic pass on my toms with it, using the suggested values in the instructions, and they sounded pretty good. First try, only a little tweaking. Even my 13" tom, which has plagued me terribly.
What it really brought to light was what I thought sounded good previously was WAY out of whack, insofar as the tensions on different tension rods. It was crazy.
I also used it on my snare, and I don't think it sounded as good as it could, but I didn't spend as much time as I should have. It still sounded pretty good, and again, there were several rods that weren't close to each other, so that alone showed improvement.
I didn't have time (or inclination, to be honest) to attempt the kick. Not at this time. I need to replace the tension rods from the old t-bar style that have been on that drum since 1980, and I don't really want any of those "T"'s off cockeyed. Yes, I know, that means I'm sacrificing the tuning for the aesthetics. I just need to replace them with conventional rods, and I'll be able to address that properly.
I'm really happy with the results, and am looking forward to spending more time with it. Shouldn't be as much of a time consideration next time that I use it. I expect that I won't need to use it all the time, but to check them every so often. And of course any time that I change the heads. Very cool.
Thanks for the advice and suggestions.