Hello once more,
The question as it applied to globulars was hard or impossible for some
people to answer. They pointed out that it depends on the darkness of
the sky you are observing from, and the particular globular you mean,
and how you define "satisfying."
clearly a very much larger aperture is required to resolve distant
Palomar globular clusters than is required for Omega Centauri.
People who observe from the southern hemisphere sometimes pointed out
that for Omega Centauri, 47 Toucanae, and one or two others, very small
telescopes or large binoculars will resolve them in a satisfying way.
But other southern observers said the sky, with regard to globulars and
galaxies, opens up at 10 inches of aperture.
Overall, the most frequent responses were 8 inches of aperture or 10
inches of aperture, or 8-to-10 inches of aperture.
Some users of SCTs or large apos, said 8 inches. Others said in effect,
satisfying globular viewing starts at 8 inches (with the implication
that it improves markedly after that).
Some apo users said 6 inches because of the pinpoint star images given
by an apo. In general, apo users suggested a smaller minimum aperture as
satisfying.
Noteworthy was the fact that a number of people found that the
improvement in globular cluster viewing as one goes from 8 to 10 inches
in aperture is much greater than one would expect.
It was clear that improvement in viewing of globulars continued as one
went to 12 inches of aperture and larger. Some felt 10 inches of
aperture was very satisfactory, and others felt more comfortable at 12.
Very large aperture for globulars, well over 12 inches, tended to give
even better views; there was no law of diminishing returns with
increases of aperture as far as globular are concerned, according to
respondents.
Some respondents found viewing a hazy granular globe of stars against a
sky background very satisfying in itself, and suggested apertures as
small as 80 mm.
I also noticed how much better Southern Hemisphere observers have it.
You can get a fuller picture of our observers's experiences by viewing
the SAA, Yahoo talking telescopes, and Astromart equipment forum
threads. Each has a variety of observers, and some very accomplished
observers or people highly knowledgeable about telescopes. Different
sorts of people post to each, but overall I would say there is consensus
among the three sources.
I think the responses have considerable implications for what sort and
aperture of telescope one feels comfortable recommending to beginning
observers. We may be more able to clearly express to them what to expect
from a given telescope, and avoid disappointments.
Many thanks to one and all for posting your views and experiences. I
hope the results will be helpful to others.
Ciao,
Bill Meyers