Fantastic effort ! Was that your first mirror ?
Quote:
Originally Posted by hamishbarker
As Stephan has already seen on "the other forum" and by email ( and who deserves big thanks for selling me the fine ground blank and giving me the (rather out of date now but they worked!) silvering chemicals.) I decided that my 550mmf4.6 was done. i read in a book that opticians often don't declare a mirror done, it is just that the mirror gets taken away from them. It was the second time (well, third if I count the time I was close except for a terribly turned outer 25mm.) that it was ready to go. I measured it at about 1/8 wavefront error a few weeks back and hubristically decided I could better that, and ended up overcorrected so had to go backwards a bit. Then I proceeded slowly, just 80 strokes and then testing, pretty much every day for a week or two.
Now it's nominally 1/5 wavelength, but a lot of that is a bit of turned down edge. maybe when I have more experience (and hubris) I'll attempt to fix that at some future recoating occasion.
yesterday was home silvering in the garden. Lots and lots of scrubbing with cotton balls, precipitated chalk and demineralised water. and then another scrub. Finally the tin chloride spray, a thorough rinse, then the magic couple of minutes with the silver solution and reducer in hand spray bottles.
There's a patch of frosty coating, so I need to redo the coating, but we had a little first light celebration with a friend and couple of beers and managed to see alpha crux through a tiny cloud hole, as well as thoroughly inspect the red anticollision lights on the nearby radio tower a couple of km away while collimating and star testing.
what a journey. I can't wait for some proper observing!
To anyone who is contemplating attempting their first mirror, go for it. one key thing I learned is the importance of having somewhere to be able to work on the mirror without needing to set up each time. I progressed a lot faster then. Also, procrastination is easy.
Hamish
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