Bright images, lots of potential magnification. Schmidt-Cassegrain scopes have a native f/10 focal ratio and are very good for deep space, dim objects, as well as planetary and lunar. A fairly long focal length can be made into a very short telescope. The primary mirror is the big one at the rear, is either concave or parabolic there is a hole in the middle of it The light reflected from the primary bounces back toward the front, where there is a convex or parabolic mirror that captures the light from the primary, focuses it some more, and reflects it don through the hole in the primary, to the eyepiece. The Schmidt-Cass is a folded optic telescope, has two mirrors. I have an Apochromatic refractor, and two Schmidt-Cassegrain telescopes. Higher f/-number means longer scope, and more magnification, at the expense of a slightly dimmer image. That's just the scope, you'll need a mount to hold and aim it. You can get a decent achromat for $400 or so, if you're just going to observe. Downside is that they are heavier, and way more expensive than a good achromat. They use three lenses, and can pretty much eliminate chromatic aberration. Achromats have gotten very good in the last few years. Achromatic telescopes can eliminate one and decrease the other. When light is bent by a lens, the component colors bend at different angles, creating a small "halo" around the image, usually a red or blue one. It will have better coatings which help decrease reflections, add clarity, and decrease what is called "chromatic aberration". I wouldn't even consider one, that's your garden variety "toy" telescope that kids get for Christmas. Refractors come in three main types the most basic is a simple two-lens with minimal coatings. Seems like when you're a noobie looking for a first scope, there's a lot you need to know in order to find what's best for you. The main reason is that mirror type scopes have to be collimated occasionally, meaning the mirrors have to be properly aligned. You might want to look at refractors for your first telescope. A 6" would still give you some great viewing, an f/8 would be about 5 feet long and 1/2 the weight of the 8". The downside to that is, less maximum magnification for small or very distant objects. If you go with a faster (optically) scope, such as a f/5 or f/6, it will be shorter. An f/8 will be about 6 feet long, and weigh about 2/3 what the 10" does. Click to expand.Drop down to an 8" Dobsonian, much easier to handle.
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