Quote:
Originally Posted by frankly1
Hi all,
I have a question for someone who has made their own mirror. I have figured a 17" blank of 19mm plateglass, and put it into the future telescope assembly. I can view the moon sharply at 840x magnification, Jupiter to about 350x (due to bad Sydney seeing at present), and defocussed stars have fairly equal rings both sides of focus, with no sign of astigmatism. Does anyone know if this is a good enough indication that the mirror could be coated? Mel Bartels says it should magnify to between 30 and 50 times per inch of aperture.
cheers,
Frank
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I think you have answered your own question in that if you can do the moon at 840x that equates to better than 49x per inch of aperture.I would definitely go ahead with the coating. If I can figure my current mirrors (22" and 25" float glass 19mm thick) to do even 30x to the inch I would be well pleased. I also have almost completed my dob structure and hope to test the first of my uncoated mirrors (22") sometime after the new year, when we get a little more night down under. Im doing my figuring outside and the temps are not to my liking (too warm).I like to work in cooler temps (around 10-15deg C with no sun), so may have to wait a month or so to fine tune the final figure.
