Figure about 50x max. for each inch of refractor aperature.


"John Honan" wrote in message
...
Newbie question. What is the main limitation of telescopes that causes the
image to lose contrast/sharpness as the magnification is increased? Is it
mainly due to the quality of the optics which causes aberrations to become
more noticable. Or is it mainly down to the amount of light gathered (the
aperture), or does the f/ ratio have anything to do with it? In other
words,
the more light that is gathered, the more the eyepiece has to 'work with'?

If aperture is the main factor, how can a 4" Takahashi refractor (for
example) produce better images than a larger aperture reflector? Is it
because a reflector loses some light in the mirrors?

Am I correct in assuming the optics in the objective lens are more
important
in the quality of the final image than the optics in the eyepiece?

Hypothetically, if I had a 10" refractor, with near perfect optics. I
would
assume that I could take the magnification to levels which would allow me
to
see very precise detail and contrast/colour on objects? Not that I could
ever afford a 10" refractor... :-)

From reading websites and FAQs my understanding is that the eyepiece acts
like a 'microscope' on the focal point produced by the objective lens.
What
would happen if I had a telescope with just the objective lens (no
eyepiece), but ensured that the image (i.e. focal point) was actually on
my
retina. What would I see?