I realized shortly after I sent that message, that I should have said focal ratio rather than focal length, but thank you for clarifying the focal ratio/focal length issue, and for your advice on the best telescope to buy.
I was wondering about the mount issue though. I was under the impression that an equatorial mount was the best kind for astrophotography. Per the S&T review of the LXD55s (Schmidt-Newts in Dec 2002 issue), the mount with an 8" was good, but the extra weight of the 10" on the same mount was too much for long exposure astrophotography. So are you saying that the alt-azimuth mount (with an equatorial wedge I presume) is superior to an equatorial mount for astrophotography, or just superior to the LXD55 mount?
Can you recommend a good digital camera to use for astrophotography? I was going to buy one for terrestrial work anyway (3-4 megapixels), so I thought I'd get one that does both. The problem however is finding one that takes a long enough exposure (>8-16 sec), although I've seen many photos published that are combinations of many relatively short exposures.
Also, would a Barlow work with a camera as well as the original eyepiece holder?
The Schmidt-Newts have a 2" dia. capacity eyepiece focuser. I imagine there are 2" barlows. Would there be any advantage to buying a 2" barlow vs. a 1.25"?
Also, would an 8" LXD55 Schmidt-Newt with UHTC coatings and a good quality barlow or the TeleView be as good as or better than an 8" SCT?
Finally, (and I'm sorry to pick your brain so much, but you seem to be so knowledgeable and very into the field that it's too good of an opportunity to pass up)a neighbor has maintained that the R naught (R0) of the atmosphere is such that the largest diameter of telescope that can be used with theoretically perfect (atmospheric distortion free) seeing is 8". However, there are many large telescopes out there (Mt. Wilson, Palomar, Mauna Kea, etc)that this doesn't seen to be that much of a problem, although with the advent of adaptive optics, even that is being minimized. Any thoughts on the R0 as a limiting factor for scopes in the 8-14" range?
Many thanks for all of your helpful advice.