Also check on quality non zoom binoculars. I use a 15 year old Pentax 10x42 for the majority of my “backyard” astro fun. My two scopes come out for special viewing nights.
Critical point about brightness ans telescopes.
As pointed out, no passive optical system can increase the surface brightness of an object without violating the 2nd law. However, many astronomical objects of interest to astronomers are not extended objects. Stars are, for almost all work, point objects, and do not behave as extended objects. Within the resolution of the optics they remain a point. This means they do become brighter with larger mirrors. So for serious astronomy, things like taking spectra, a bigger light bucket the better. Similarly, you do get more photons with a bigger mirror, even with extended objects. So if you don’t care about creating an image (and maybe just shovel the photons down a pipe into a spectrometer anyway) you still win with a bigger scope. So things like looking for red-shifts of zillions of galaxies can be done with nice big telescopes.
The light-bucket amateur scopes alluded to above are the Dobsonians. Named after their creator. The ethos being that nothing beats light grasp for visual observing. Everything is subservient to that. So money is spent on bigger diameter ahead of any other convenience or cosmetic. So, melamine covered chipboard is used to make the entire structure, with only the most basic Teflon pads for bearings, and a cheap cardboard tube. No equatorial mount or motor drive. But you get maximum light grasp for your dollar. There is much to be said for this - especially if you build it yourself.
I made an 8" Dobsonian! Most expensive part was the prefinished mirror. I could have saved more and been more involved if I polished a mirror myself.
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It’s been a while, but as I remember, the most important thing for a telescope is aperture, or light gathering ability. Thus a 12" diameter mirror is better than an 8". Next consideration is focal length and it’s usually expressed as an “f” number. That’s the ratio of focal length to diameter. Thus a 6" mirror with a 48" focal length would be rated at f/8. The lower the f number, the wider the field of view is.
Magnification is rated by the eyepiece, and the ability to resolve higher magnifications has more to do with weather conditions than anything else. One needs very stable skies to use that 6mm eyepiece.
Mounting is critical if you plan on doing photography, a little tripod will shake around too much during hour long exposures. A simple and relatively cheap mounting system is to cement a V-8 engine block into place with the crankshaft as your polar axis. Not much will move this while your shutter is open.
Very cool! I never heard of these. What was your experience actually using the view the sky?
Well, the most important thing with a telescope is the quality of the optics. But there’s a limit, practically speaking, to how good the optics can get (the diffraction limit), and optics from reputable telescope companies like Meade, Celestron, and Orion will all be diffraction-limited. Once you’ve got that, then aperture is what’s most important. A large aperture will improve everything, except portability and convenience.
Focal length is important, but it’s a trade-off. If your goal is to see faint things, then you want a short focal length. If your goal is to see fine details in things, then you want a long focal length. Long focal lengths also mean a long tube, which can be inconvenient.
There are two choices for type of mount, either altitude-azimuth, or equatorial. An alt-az mount is cheaper, simpler, and easier to set up, especially for a larger scope. An equatorial mount makes it easier to track stars. An equatorial mount with a clock drive is essential, if you want to do photography.
Never, ever buy any telescope that advertises how much magnification it has. You can get any magnification you want by switching eyepieces, and a scope with high magnification but low quality will just turn small fuzzy blobs into big fuzzy blobs. Making a big deal about magnification is a good sign that pretty much everything about the scope will be crap.
A Dobsonian is an excellent choice for an amateur, since you can get a very big and high-quality scope for your money, that’s relatively easy to set up (put box on ground, put tube in box). It’s tough to install a drive or computer controller on one, though, so you’re going to have to find things yourself. A naked-eye reticule like a Telrad will help a lot, along with a book of interesting objects with the size of the reticule marked on the charts. You’ll also need to adjust the scope every so often to stay on target (precisely how often depends on how close to the pole your object is and how high your magnification); I’ve found that I can adjust it with my knees while looking through it, but that takes practice.
Wonderful.
Teaches you how to “star hop” too. (You’ll be glad you looked up that term!)
No photography on that scope for me. I piggyback or shoot thru on my equatorial mount for that.