That's hard to believe. I'm doing real good if I can get .003 repeatability. (fixed light source) Typically, I often see differences of .005 (or more) between readings if I move the focualt tester just a bit. (I often do this so it's not so easy to "cheat" when doing the second set of measurements) Only by averaging together several sets of readings do I feel like I _might_ be getting readings accurate to .003" or so. And this is only at the edge - near the center it's nowhere near that good.
The funny thing about this is that if his testing is really that accurate, it's probably wasted anyway... He mounted that 12.5" mirror on THREE blobs of silicone sealant. No 9-point floating mirror support! ________________________________________________
Greg Granville - N3SPE - (day)814-865-3310 ARL-PSU gag1@psu.edu (eve)814-339-7244