Oak Creek Observatory

SBIG ST-7 CCD Camera

Now for the ST-7 camera. I started using the camera with a prime focus fitting between the telescope and the camera. It is much more stable than the nose piece as furnished by SB. That fitting screwed onto the f 6.3 focal reducer on the tele and then the fitting screwed into the optional fitting as supplied by SB. on the camera. This made for a very stable and secure mount even with all the wires and cables hanging onto the camera, etc. The telescope and camera are connected to a NEC notebook computer (486 type) using The Sky and Skypro software with the former to control the tele and the latter to control the camera. Actually, all the camera functions are maintained by use of the software including shutter speed, time of exposure, number of exposures, pixel size, sensitivity, temperature, how to guide and a host of other options.

This camera will guide on stars as faint as 14th mag without any problem. It can see stars as faint as 20th mag. and galaxies at 18th or 19th mag. I figure I can go out to about a billion LY's. with this setup. Both track and accumulate T&A and full guiding work very will. I find that Skypro works better with the T&A while full guiding works better with CCDOPS which comes with the camera. I take most pics using the 2nd sensitivity as it is quicker to download to the computer and gives better images for the galaxies I am looking at. High sens. is good for some things but I don't use it as much. I almost never use the lowest sens. the pixels being too large. When I take an object in all 3 sens. and get them on my fast computer in my office I almost always find that the one taken with the 2nd sens. is the best of the 3. The longer you take an image in total time the better the image and the cleaner the background. The signal to noise ratio is much better as the noise is mostly out of the way. Six to ten minutes usually works for me here, but sometimes I go to 15 or 20 minutes, but often find little improvement. When I use T&A I find that one minute or 2 minute exposures added together work well. This is especially true using the f 3.3 setup. The resolution at f 6.3 is slightly better than at 3.3 but it depends on what you are doing and need.

Everything about the camera works very well and it is all in the software used. That is mainly why I went with the ST-7 rather than the Meade cameras. After I researched the subject I went with the ST-7 mainly on the basis of the software. It turned out to be a fortunate decision as the problems with the Meade software still haven't been totally resolved. The hardware of the ST-7 is bulletproof. It just keeps working and working without a glitch. For f 3.3 I use the Maxfield.

As I am doing galaxies mostly, I can do from 20 to 30 each night. On some frames I will get a whole cluster of them, sometimes 5 or 6. I leave everything all set up on a permanent basis in the observatory so it is very convenient to use whenever the weather and moon phase looks good for what I want to do.