Amateur builds 70 inch reflector telescope!

Originally posted by twhitehead
Interesting. Of course the article makes an obviously false statement suggesting it is the most powerful telescope on the ground. Not even close.

I have often wondered what it would take to make a really big mirror using super cheap methods and whether size could make up for quality.

Also that spy satellite mirror, is, I believe, larger than the largest in use on a commercial satellite.

Yeah, he should have said "Amateur' but it's an omission. It is close to Hubble, I think it is 94 inches. So if it was in orbit the res would be close, Hubble clocks in at about 0.05 arc seconds of res so I imagine his would produce easily 1/10th arc second pictures. Of course taking pics of the ground from orbit introduces the same kind of distortions as being on the ground and looking up so you can kiss that 0.1 arc second mostly goodbye in a spy sat. A sat with a 1200 mile circumference orbit and 1 arc second parsing a circle into about 1.2 million parts says it should have only about 5 feet res and 0.1 arc second therefore about 6 inches. Maybe possible barely.

I did some math on that scope and to expand on the 7X50 vanilla binocular, you would get the same image size as those binoculars but at about 250X mag! So you could do 2500X if the optics were up to it. Of course the atmosphere would have something to say about that much gain🙂

BTW, did you know there was a spy radio telescope in orbit too? Five hundred foot dish, of course painted or stained black, you would never see it.