At 2:10 PM -0700 5/1/98, Mark Cearley wrote:
>... Is it reasonable to think that CCD
>images might be any sharper with the vixen. 4"Fluorite refractor Vs
>10"sct?...

Prettier, maybe, but not really sharper. Assuming, of course, that your
sct is well collimated and has no other problems. There is an unavoidable
loss of resolution as aperture decreases. The usual rule of thumb is that
a fine refractor is roughly equivalent to an sct or newtonian about a third
larger. So you're 4" refractor might equal a 5 or 6 inch newt. It won't
even come close to a 10". Again, assuming no obvious optical problems.

Some say that a smaller scope is less sensitive to bad seeing than a large
one. Thus in bad seeing the advantages of larger aperture may be greatly
reduced.

I've had lots of opportunity to compare my 12" LX200 with many expensive
large refractors. There is no question that the images in the refractors
are prettier most of the time. But when the seeing steadies they don't
have a chance.

That is not to say that the Vixen 102F is not a fine instrument. It is.
But it's only 102mm. The laws of physics limit its potential.

---
Bill Arnett "Science is a way of trying
San Jose, CA USA not to fool yourself." -- Feynman

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