Learn Me: Telescopes

My sister loves astronomy and really wants to own a decent telescope. I am hoping to buy one for her at some point but know absolutely nothing about them. Is anyone here into astronomy that can shed some light on the subject?

I don't know when I will be able to purchase one but what is the new vs used market like for these? What are the best places to buy from? Etc etc etc.

Thank you in advance!

Joshua

Just make sure to get one before November:

http://earthsky.org/space/big-sun-diving-comet-ison-might-be-spectacular-in-2013

Of course, you might not need one for that thing, but it would make it more spectacular.

I'm shopping, too. Looks to me that for around $100, you can see the rings of Saturn. I've just been looking on Amazon at some of the "popular" brands, and intend to avoid the ones with tracking computers.

Quick breakdown.

There are several basics about telescopes.

The actual telescope There are Reflectors and Refractor telescopes.

Refractors use a couple of lenses to gather light and magnify the image similar to a set of binoculars.

These are nice for local objects like planets, the moon and close stars. Larger ones can see deep space objects like messier objects in decent detail. They will have issues seeing deep space objects in great detail due to the problems with light gathering. Not saying you can't but the difference between a 3 to 4 inch refractor and a 8 to 10 inch reflector is very pronounced.

The advantage to refractors is that they are compact and lightweight. This makes it very easy to move around with one person, more on that later.

Due to the way that they are manufactured they can vary from a couple hundred dollars for a 2 or 3 inch all the way up to 5 thousand+ dollars depending upon the size and quality of the lenses.

Reflectors

Reflector telescopes (common types) use a large primary mirror to gather light and send it to a smaller secondary mirror which then sends it through the eyepiece.

Reflectors fairly cheap to manufacture (you can build one at home with a nice piece of plate glass as a fun project) and gather light very well the larger they get. They are very good for viewing deep space objects like other galaxies and messier objects in great detail the larger that they get. Local bright objects often require a cap of some type at the end of the telescope to view because they have a shorter focal length (the smaller light inlet increases the focal length) and they will gather so much light that the moon becomes painful to look at. Jupiter and Saturn aren't so much of a problem.

They also vary in price form a couple hundred for a good one to the price of a new car for larger ones.

The disadvantage to these is that they can be very large if you want a large focal length or bigger mirror to gather more light.

There's a subset of reflectors called Schmidt-Cassegrain which has a piece of one way glass at inlet of the telescope which reflects the light back again essentially greatly increasing the focal length of the scope allowing you to have a good F value and gather more light for deep space viewing in a much more compact form factor. Last I looked they were at a premium over the cost of a traditional reflector but were 1/4 the size with the same focal length.

There are two common types of bases for reflectors.

Dobsonian: Basically a box which the telescope sits into

These are simple to build and easy to move around because they do not require any counter-weighting systems. The downside is that attaching an automatic tracking motor to them becomes difficult if you want to do any photography or simply show a line of kids an object without realigning the scope every few minutes.

Equatorial: These are counter-weighted bases for the telescope which gives you a bit more of a freedom of movement. This makes tracking objects much easier and allows for much finer adjustment of the telescope. Motors can be attached to these to do the automatic tracking.

The big disadvantage to these is that the larger the telescope gets the larger the amount of weight needed for the counter-weight system (the 16" telescope my father and I used to move around, and still do when I'm home to help him, uses 150 lbs and the base weighs in at a good 100 on top of that) and the larger the base becomes.

Brands

My experience really just involves two brands: Meade and Orion.

I grew up with Meades 6" reflector, 10" reflector, 16" reflector and a 5" refractor. Meade is pretty much the gold standard for hobbyists. They are very well made, excellent quality optics, and have excellent support. They also tend to be on the more expensive side of things but as with most optics you really get what you pay for, unless you plan to grind one yourself.

I currently have an 8" Orion on an dobsonian base I picked up for a couple hundred bucks at an auction. It's easy to use an move around, the tube is aluminum, and I can move it without the assistance of another person. There were a couple draw backs though. The focuser was pretty much plastic and lacked the fine adjustment I liked on the Meades, that was relaced with a fine adjustment metal bodied one. The view finder was pretty terrible as well but I now have a red dot on it. The mirrors are pretty good however, they're nice and clean with very little distortion. I'd really rather have my Meade stuff but since I move around the country so much it's really hard to justify taking the risk with something that expensive all the time.

There are a couple other brands but if you can swing it I'd highly suggest a Meade.

Eyepieces

There's a lot to be said here since they are often the determining factor in what you see and how well you see it.

Basically eye pieces determine the field of view and magnification of what you see. You can get everything from high magnification narrow angle to wide angle low magnification to coated eye pieces which filter light so you don't need to use the afore mentioned cap, depending upon what you are trying to see.

A mixture of eyepieces is suggested but a nice wide angle and a nice narrow medium magnification are what I'd start with. This allows you to find what you are looking for in the view finder, narrow it down with the wide angle, then get in close with the narrow. The "power" factor on these can be deceiving because they might have a high magnification but really crappy focal length which makes things fuzzy. For the narrow field of view you want a good focal length and good magnification. I would tell you what I have but I don't know right off the top of my head without accessing my box.

Eyepieces can be ported for telescope to telescope so skimping on them tends to hurt you in the long run because you just have to buy more.

Star Chart

Do yourself a favor and get one so you can find thing objects. That's seriously the best advice I can offer. If you're looking for an object just by skipping around it gets a bit old and frustrating. They're cheap and if you subscribe to Astronomy magazine it comes with an updated one every month.

Also Astronomy magazine is a very good resource for anything related to the hobby. They have great reviews by people who really know their stuff and do everything from hobbyist budget on up to big budget.

Hope this helps and not confuses more!

Also you can find them used, though I have no idea where to shop since I buy a new one every 10 years or so usually at an auction or swap meet. Most of the time they don't hold their value well because the people who are selling them are often selling someone else's hobby and have no idea what they're worth. The big thing to look for on used is to make sure that the lenses aren't cracked or scratched on a refractor and to make sure all the silver is on the mirrors on a reflector. Also make sure they haven't been cleaned with windex or another ammonia based cleaner because that affects the silvering.

There's often big star parties in the northeast at least Stella Della and Stellfane come to mind. You can learn a lot by going to them and talking to the amateur astronomers there. Plus they usually have really good swap meets.

Thanks for the information guys! I'm looking on Ebay now...