Hello, Tony,
I think this paragraph below is remarkably insightful and goes to a major difference is observing
techniques and philosophy that is related to equipment and type of object: those who are seeking
detection and those who are seeking detail or structure, of you prefer that word. The larger scope
permits seeing detail on galaxies, or at least structure, and a small scope does not. Each approach
is valid but they are very different.
Unfortunately, galaxies get fainter faster than amateur scopes get bigger, so many users of 16
inch and larger scopes who look at Abell clusters of galaxies are pretty much limited to the kind
of detection one might do on the Messiers with a three inch refractor, as far as I can tell from
their observing reports. Of course the members of Abell clusters are so far away that seeing them at
all is no doubt deeply gratifying.
I myself favor objects that I can see some structure in with whatever scope is at my disposal,
but I do mix in a bit of detection as well.
Since I am interested in structure, since it gives me the " wow!" effect, I try to choose a
telescope by the following algorithm: first I define the boundaries of what is reasonably convenient
for me, in terms of set up, portability, and ease of use at the eyepiece. Then I choose the largest
apertures within those boundaries. Then I choose the highest quality scope of that aperture, that I
can afford.
This algorithm has led me successively, based on my living conditions and observing
circumstances at the time, to a 1.25 inch hand held RFT from ANRA,
then to a 6 inch f/5 Dob from Telescopics, and then to an 11 inch ELT Dob, all of which have been
wonderful instruments. Each one made possible the observation of structure, but in different classes
of objects.
I think recently you posted in SAA about a procedure for choosing a telescope, giving different
weights to various aspects, such as quality, size, optical design, and so forth, but I can't seem to
find it and would appreciate it if you would refer me to that posting, as I thought it was astute. I
can't seem to find it in a google search.
Ciao,
Bill Meyers

Tony Flanders wrote:
(snip)

Finally, it sounds as though you are still somewhat stuck in a
small-scope mentality; most of the targets that you mention are
small-scope targets rather than big-scope targets, and when you
talk about big-scope targets like galaxies, you talk about them
in small-scope terms -- detectability -- rather than in big-scope
terms. In a 10-inch, you should be looking for the spiral arms
in M51 or the dust lane in NGC 3628, not just thinking about
detectability and maybe gross morphology.