Hong Kong 8.5" lens, any reviews?

Has any one bought and tested the lens manufactured (or shipped out of) Hong Kong frequently advertised on ebay? Below is the description on ebay:


Modern designed 8.5" F/12 professional telescope lens,doublet,air-spaced,included high quality aluminum cell. FULLY-MULTI-COATED for all four surfaces,over 97% light transmission. NEW,never used. star testing showed 1/6 PV,excellent airy-disc. quality is as excelent as D&G's which is the one of best achromat on the current market.

D=8.5" (222mm)

F=12 ( 2700mm)

Lens Type: BK7 + F3 (SCHOTT)

Glass grade: A

Coating range: visible light from 400nm to 700nm.

buyer pay $80 DHL shipping cost,three working days delivery to your door.

Bill,

Yes, I have one of these, which will eventually get folded and paired with a Chromacor [I hope]. It is in a temporary tube at this time. I tested mine at Chabot Space Science Center's telescope making class. It tested very nicely. In practice it needs an aperture mask to 7.75" because of a slight turned edge. I put the focuser, a 2.5" D&G, in a sliding section in order to use a binoviewer without a Barlow.

You will need a BIG mount; I use a homemade GEM similar to OpticCraft's, with 3" shafts, and it needs to be about 6' high, minimum.

I can't speak to the spec's you've been given. Have to take someone's word for those; my lens is coated, and shows no ghosting, but it doesn't seem a very noticeable coating. I paid about 2K for mine, three years ago.

Cooldown is an issue. It's a HEAVY piece of glass! but once that's done, WOW! Size matters!

The reason why these aren't sold on AM [it is my understanding] is that the exporter can't get an account. I purchased mine through AstroBuffet, paying a bit more for someone else to take the risks.

J.A.

I believe Ken Dukat built one - see Ken's Rings in the Sponser section.

Thanks for the feedback