Hi Stan,
What a great opportunity you have had to have a look inside this observatory. I have been interested in astronomy from a young age (my teachers reckoned I was always looking at the stars) but I have never been this close to such a large telescope.
One thing that disappoints me a bit about the photograph is that we do not get to see the top of the scope, it has just been cropped a little too tight. Perhaps this might be an excuse to buy a wider-angle lens, but at a hunch you might also have been able to make this photograph by simply taking the photo in the vertical.
As for the use of high ISO, I do not think that is a problem, particularly with a camera like the Nikon D700. In a situation like this though, it is worth taking on a tripod.
Now the one thing that I am going to suggest to improve this photograph is to add a few herbs to it. This is one photograph where you could use high dynamic range treatment to increase local contrast and bring out the detail. I have applied HDR image below.
I hope you get another chance to visit this telescope and to explore photographing it some more (ask if they have an F-Mount adapter to fit your camera to the scope!!!).
Cheers, Anthony
Image Doctor's edited version
