16" Mirror on ebay

[Curt]

I was looking on ebay as you do for astro stuff and came across this otsahowski 16" f4.5 mirror with a chip on the back.
What are the negatives of a chip of this size.
Would it detract from the image at all, strain on the glass. Would it get bigger from vibrations during transport.
At $1800 plus shipping and import tax it seems a bit pricey for a mirror with such a flaw.

[billdan]

Sounds expensive to me, You can buy a new 16in F4.5 ftom Bintel for $1600.

Regards
Bill

[alocky]

That chip is unlikely to have any impact on the image whatsoever. Even if it was on the front you would not notice any image degradation if you masked it off. More important is the quality of the figure of the mirror, and how well it is mounted. On balance of probabilities it will probably be better than a GSO mirror, but will your observing conditions, eyepieces and the rest of the telescope allow you to see the difference?
The chip wouldn't bother me at all.
Cheers,
Andrew.

[SkyWatch]

They have a good reputation, and the price is actually pretty good compared to their normal price (and 1/2 the price of an equivalent Zambuto!).
A chip like this won't effect the image, although you might have to put a bit of black paint on it if you can see it from the front.
Speaking of which, I am surprised you can see the chip in the photo taken from the front in the e-bay ad: I would have thought you wouldn't be able to see through the coating. You can see what looks like a bit of reflection of the central alignment ring too: maybe it needs a new coating? Someone else might like to comment?
If you are worried, I wouldn't get it; you still have to build a scope, and there is no come-back from this sort of purchase...

Good luck!

Dean

[Curt]

Thanks for the replys guys.
After doing the math and some advice its probally best to leave this alone. Being so far away without even looking at the mirror condition is not the best idea. I already have a gso mirror from a old lightbridge l used to have. I transferred that into the telekit l built. After seeing what a good mirror can do its hard to go back to the gso. Feels like im missing out.
Im in the process of getting some quotes now for a premium mirror. They are definitely worth it.
Cheers Curt.

[MichaelSW]

Recently I met a fellow who works at the McDonald Observatory near Fort Davis, Texas. He told me a story about bullet holes in their 2.7 metre reflector.

Found this link on the WWW.

http://astroanecdotes.com/2015/03/26/the-mcdonald-gun-shooting-incident/

[el_draco]

Yep... that jumped straight in to my mind as well...