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Big Refractor ATM Parts

Started by Rick Dingus, 11/27/2011 08:45PM
Posted 11/27/2011 08:45PM Opening Post
Hi everyone,

At a party last night the brother of an old friend of mine told me about his family's long-standing interest in astronomy. He also told me had inherited the lens parts for a large refractor telescope his uncle had been building before he died. He has two ground and fine polished glass lenses with a diameter of at least 8 or more inches! They are stored in a box in his attic, wrapped separately, but meant to go together, probably as an achromat. He doesn't know their focal length, but invited me to take a look. He has a machine shop and some machining skills, might help me finish building the telescope as a project with my students (I teach photography at TX Tech University) so we could all share its use.

I know how to determine the focal length of a compound lens assembly, but these lens parts are not put together. So I don't know whether they need to be assembled close, cemented and touching, or, if spaced, how far apart. I also don't know what kind of glass they are made of, whether or not they were coated, or intended to be coated.

Any suggestions for how to determine such things as we consider whether or not this is worth pursuing? Or useful references or other resources you could point us to?

Thanks for considering this and for whatever ideas you might share.

Hope you've had a great Holiday.

Cheers,

Rick
Posted 11/27/2011 09:19PM #1
Rick, you could always air space them with pieces of tape and check them out on a star test. If you do a search for Roger Ceragioli's refractor making pages there will be enough info to get you started. I have to believe there are some notes around the shop where these were made, which would help. Depending upon the price, I'd have a difficult time staying away from an 8 inch refractor objective. I'd bet on a close spaced system.