From: "Herb Kasler" 
To: "Jerry B. Hillman" ,
        
Reply-To: "Herb Kasler" 



Jerry,


Is this a short focal length mirror? If it is, you may find that you have
polished the scratch out by the time you get it figured properly. I got a
couple of pretty nasty scratches early in the process of figuring my
16" f/3.9 mirror, and they were pretty much gone by the time it was
done, since I had to go back to a sphere four times befoere I got it right.
 Of course there were new ones to replace them at the end, but that's
another story... If you hit it just perfectly the very first time, then
you'll still have that scratch, but if you have to start over a few times,
it may well be gone before you're done. At any rate, the scratch itself is
a purely cosmetic issue. It will have no noticable effect on the
performance of your optic. I would think long and hard about how important
purely academic questions of perfection are to me before I undid all those
hours of polishing, if I were you. Especially if I had a perfect sphere.
Mirror making is a sufficiently Sysiphean undertaking without sending
yourself back to the beginning over something inconsequential.

LAter,


Herb.

--- BBBS/NT v4.00 MP