[rumples riot]

Great tips and commentary Anthony.

Hard to contribute to a fairly comprehensive article. However, I just want to add something from a SCT users perspective. There are not many of us here so, it won't matter to many of you.

As you know collimation is one thing that I concentrate on the most. Collimation in SCT's is extremely critical. The reason for this is that given the secondary acting as a 5x multipler large errors in collimation become visible with just a slight misalignment of the secondary to the primary. Collimation should be performed ideally on nights of excellent seeing for an SCT. However, this is rare in my neck of the woods and have resorted to buying a Pico Star (artifical star). This star is mandatory as a collimation tool for SCT owners who want to do hi re planetary imaging and get good results. It can be performed everytime you image and therefore your scope will always have perfect collimation. PS while SCT's hold collimation well, minor deviations can occur just from differing temps. These tiny amounts affect final images significantly.

Another issue for SCT owners is the dreaded tube currents. Cooling of an SCT will take much longer that other systems. The reason being is two fold. The tubes are generally very large and hold a lot of air and the system is closed. This make it take longer for the mirror and tube to adjust to ambient temp. There are several ways around this issue, but two that I know are permanently mounting the scope outside and forced induction of air into the tube using an SCT cooler. The former is the method I use with my scope permanently house outside on a pier. It is properly protected with several layers of protection from heat and water. Using this method the scope is ready for work 1 hour after sunset. If I housed the scope inside, it would take up to 3 hours before the scope was ready for work.

Anyway that is my immediate imput. Great topic.