Bought my very first scope. The highly acclaimed Celestron 9.25 XLT OTA. When I first took it out of the box, the first thing I noticed was a one inch diameter scrape on the back casting that was covered up with paint. Oh well, no biggey. So used the scope about 3 or 4 times to get used to it. My friend says never look into the big end of the scope. Well, I looked into the big end of the scope and saw about 8 or so paint brush blobs to cover up the mistakes. Oh well, no biggey. I also saw grease all over the flat black paint inside the baffle tube. Oh well, no biggey.
So the other night I take my bad-arse scope out and match it against my friends small Mak. In his Jupiter was sharp and lots of detail. I looked in mine, pretty good collimation and Jupiter looked like thud. He looks in my scope and says, what's up with that?
So figuring the collimation was almost perfect, I decided to have the scope tested on an optics bench with a Zygo Interferometer by a highly qualified optician. It wasn't pretty. The astigmatism shown on the wavefront measurement was way out of spec. This was a biggey.
So the dealer has made an offer to take it back, having seen the wavefront analysis. He is really afraid to do this though because he knows in days I will know if this next one is bad also.
So I will keep you folks up to date on whether there may be a new trend in bad mirrors or whether it's a fluke, but I am hearing some issues may be happening, but not from everyone.
I'll get back to you. Joe
So the other night I take my bad-arse scope out and match it against my friends small Mak. In his Jupiter was sharp and lots of detail. I looked in mine, pretty good collimation and Jupiter looked like thud. He looks in my scope and says, what's up with that?
So figuring the collimation was almost perfect, I decided to have the scope tested on an optics bench with a Zygo Interferometer by a highly qualified optician. It wasn't pretty. The astigmatism shown on the wavefront measurement was way out of spec. This was a biggey.
So the dealer has made an offer to take it back, having seen the wavefront analysis. He is really afraid to do this though because he knows in days I will know if this next one is bad also.
So I will keep you folks up to date on whether there may be a new trend in bad mirrors or whether it's a fluke, but I am hearing some issues may be happening, but not from everyone.
I'll get back to you. Joe
