[Ronja] Replacing Chinese lenses

[Karel Kulhavy]

> Hi Indian (and other) Ronja hackers,

> I bought beautiful indian optical grade lenses (BK7) for about 4-5 USD each through a 
> school physics material supply house.

> They have exact focal length, and are much better cromaticly through better glass. You 
> can replace a lens without adjustment
> which you cannot with a lupe lens.

What's the diameter of the lens and the manufacturer contact? Does it have a similar
focal length like a magnifying glass?

CL<