Some Terminology

I was asked about some of the words I've been tossing about, which were not usderstood by all the people reading. Try and remember, by using lingo I am only trying to appear smarter. Here are a few definitions.

Mount-the mechanical pile of stuff that is connected to the telescope, which allows it to point in different directions. It includes (in my case) the motors needed to keep the scope pointed at the same place in the sky while the Earth turns.

Tripod-well, the tripod. The mount attaches to the top of it. While often sold together, they are unrelated, and have their own demands for quality.

Clock drive-those motors can move the scope around at different speeds and directions (moving the scope from target to target is called slewing) but originally, all a motor did was to move the scope with the Earth's rotation (actually opposite that), and that is called tracking. They were given the name of Clock Drive many years before people were even using electric motors; being spring-driven, they were, in every way, clocks. With modern stuff, one set of motors is used for both needs-tracking objects, and slewing. When tracking, the mechanism can still be called a clock drive.

Subs-each photograph I take is actually made up of a lot of shorter photographs. If a faint galaxy would need an exposure of 30 minutes (meaning, leaving the "film" exposed to it for 30 minutes) I would likely take 60 30-second pictures, which are added together. Each individual exposure, or click of the camera, is called a sub. When I stay aimed at one object shooting a lot of subs, that is called a set. Sets are then stacked to produce my final photos.

And just how important is a clock drive? Many telescopes are sold without them, even these days, and even some pretty big scopes. Well, the Earth takes 24 hours to rotate the 360 degrees of one circle. That works out to one degree of rotation every four minutes. The full Moon is almost exactly one half of a degree across. Which means, if you focus a scope on the moon, in two minutes it will be completely off center in two minutes. The bottom line is that even a wide-angle scope like mine can only take a picture for about 3 seconds without a clock drive; after that, the stars are stripes, not dots. Most of my short astrophotography career has been learning how to align the various gears and axes of the mount to allow longer exposures. Those big scopes sold with no clock drive are definitely not to be used for photography. (Usually they are a close relative to my scope, called a Dobsonian. A Dob is not actually a type of telescope, just a type of mount for one.)

Hope that makes it clearer. And please, if I say something you don't understand, ask about it-that's why this blog is here. This isn't supposed to be an astronomy textbook-I'm just going to write about what I'm doing, mostly for fun, so without questions, I won't know what other info is important.