Re: atm Oily optics

Stephen Tonkin (astro@aegis1.demon.co.uk)
Thu, 03 Aug 1995 20:19:45 GMT

In message <9508022330.AA05081@epa.epa.ericsson.se> Bratislav Curcic writes: >
> Careful here ! If that old 60mm with "unbloomed" objective is
> what I'm thinking of (a Russian 60mm f/10), it's lens is a real
> Fraunhofer design, where R2 <> R3, and where air space _IS_ a
> calculated optical element (and R4 is _very_ slightly convex).

Thanks for the warning, Bratislav. In fact, it's an f/15 -- R2=R3, R4 is *flat* -- at least, according to the reflections I get off it, it is.

> You might be suffering addittional chromatic and spherical aberrations
> because of that. Do some star testing before/after.

Chromatic aberration seems, if anything, better than previously although, to be honest, I hardly looked through it before stripping it down.

Another advantage of the cedar oil is the slight aroma of coniferous forest (or is it lavatory cleaner?).

Clear Skies, Steve <sft@aegis1.demon.co.uk>