http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productID=1749&search=1

Scroll about half way down and you'll see the 6.6x (150mm focla length) and 10x (100mm focal length) achromats with 50mm diameters.

They aren't glass, but magnesium difluoride.

Anyone try these? Looks like they could be mounted in a tube or possibly a 52mm filter ring?

Peace, Rolland