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Hi Frank,

I notice that no one has responded. I'm not an expert but several years ago I bought an Astra IIIb (3b?) and the papers included were a mix of Celestaire and GLH. I looked on eBay and tried to find a way to be sure I had a real Astra. I don't know where my notes are but, with the sketchy information listed on eBay, there didn't seem to be much of a pattern. Serial numbers jumped around - not skipping a few numbers but earlier sextants having higher numbers than later ones and 5 and 6 digit serial numbers being used during similar manufacturing, or sale, dates. I'm not sure if it's possible to say "This one has a 20 mm lens and that one has a 60 mm."

There's a "buyer beware" statement from Celestaire on the special requirements for their Astra versus the poor quality control on those others. There is also an opinion on here that it's unlikely that the Chinese kept two separate manufacturing lines and that they were all probably decent quality. I've never read anything on an "unusable" GLH.

To your last question - yes. A larger objective lens gathers more light. That might help in some cases.

Yes, I'd buy one. I think I've read that, after the plastic Davis, the Astra is the most common sextant that students bring to a CelNav class.

Regards, Noell