For the last several years I have been able to photograph at the George Observatory (south of Houston) using both their big 36" telescope and their 14" Celestron telescope. It is a wonderful place to visit and an honor to be able to use this magnificient equipment.
Ok. It is not free. It cost $450.00 a night, but for me it is worth it. Plus being inside a professional observatory is very inspiring. Few people in the world have had that privilege.
The observatory is owned by the Houston Museum of Science. It was purchased from LSU, and was originally built back in 1967. The mirror has been reconfigured and re-coated, so the images are sharp. However, the tracking system has some gear problems from time to time.
The main telescope (36"), uses 2 guide scopes. One is a 6" refractor about an F/10? and the other is an old 11" F/12. The problem with the 11" is that it is not an APO (apochromatic) lens. That means it does not correct for chromatic aberration as well as spherical aberration. Thus, any image has a rainbow around it. This is not good, incase you are not sure what I am talking about . So, the 6" is mostly used. However, to tell you the truth, the alignment is spot on, and when you enter in the coorinates of the object you wish to photograph, you will see your image as soon as you look through the eyepiece at prime focus. In the old days spotting scopes were critical for photographing the night sky. Back then, it was necessary to take exposures from 10 minutes to 1 hour. Film is not as sensitive to light as a digital camera. So during that time, you had to sit at the telescope looking through the guide scope and moving the telescope by just a hair if it began to move off. Now days, with digital cameras, most exposures are no longer than 60 seconds, and with that short of exposure time, variations in scope movement is insignificant. So, guide scopes are really not as important with digital imaging.
Yeah, it is a big boy. Really, it is not used very much. Also there is a Celestron 14" F/10 sitting there in another dome. So, what are you waiting for, it only cost money, but it is worth it.