Hello, are you a telescope enthusiast?

DrZiplock

It's been over two decades since I last looked at buying a telescope and that was when I was researching one to put on my Christmas list for Santa. I'm guessing that things are a bit different now.

In the not too far future, I'm going to be buying one as a gift for my lady friend. She's studying to be an earth science teacher and much of her work has been concentrated on space (cause that makes sense). I'd like to be able to buy her a pretty good telescope, but I don't even know where to start. Though, I do have a few options that I know I'd like it to have:

1) Able to see stuff in space
2) Ability to plug in the coordinates of a few objects and have the scope track to where they are (I believe this to be a more and more common feature)

Anything other than that is an added bonus. What should I be looking for? You tell me.

What brands are good?
Any specific recommendations?

Budget is a few hundred dollars. I'd rather not break the bank, but I am willing to put a bit towards this.

So, H/A, anyone know a bunch about telescopes?

Thanks, much!

Sarksus

What you're asking for is a telescope with a "GoTo mount". These things make it easier to find objects but the operation of the telescope itself becomes more complicated and it's more expensive. Can you be more specific about your budget? GoTo solutions come in a few different flavors. The most common is a GoTo system paired with an equatorial mount, which is a tripod and a mount that allows the telescope to move on the same axes as the Earth. Basically it allows the telescope to naturally follow the movement of the sky as the Earth rotates. This solution is expensive and if you cut corners you get something that's flimsy and inaccurate. Equatorial mounts also have a higher learning curve as their operation can sometimes be considered unintuitive because of the specific way they move.



Another solution is the equatorial platform. Instead of a tripod the telescope is mounted to what's known as a "dobsonian mount" which is basically a wooden box that allows the telescope to be moved up and down and side to side without any regard for the Earth's rotation. Underneath the dobsonian mount is the equatorial platform, a motorized platform that moves the telescope for you after receiving instructions from the onboard computer. This solution is a bit less expensive and will work as far as visual viewing is concerned (taking pictures with a dobsonian is not advised).



Another solution is a dobsonian that has the computer but not the expensive motorized platform. What happens here is that you calibrate the telescope, input what object you want to see and then the computer tells you how to push the telescope in order to get the object in the eyepiece. The two telescopes I showed above cost around a thousand dollars. The bottom telescope is an eight inch reflector type telescope. If you get a dobsonian with just the computer and the same eight inch reflector telescope it costs around $500 instead of $1000. There are also six inch varieties which are a hundred dollars less.

When money is a concern but someone still wants some help finding objects I usually recommend this solution. Specific models include Orion's Intelliscope line: http://www.telescope.com/Telescopes/Dobsonian-Telescopes/IntelliScope-Dobsonians/pc/1/c/12/27.uts

So yeah, I think that would be your best bet but of course you lose automated tracking. You also have to consider that reflector telescopes need to be calibrated every so often. What this means is that the mirrors inside of the telescope need to be aligned (commonly referred to as collimation) properly to the light path and each other. A refractor, which uses stationary lenses, requires less fuss but they are more expensive. The draw of a reflector is that you get to see more with less money.

You might consider learning more about it yourself before you make a decision. It's information that you will use so long as you participate in the hobby so it's a good investment. You'll also be better able to select a telescope yourself and avoid getting something that will only frustrate you. With that in mind I recommend the Backyard Astronomer's Guide. It's a big book that will get you up to speed on many aspects of the hobby. Your friend will also appreciate having a book like that to guide her. http://www.amazon.com/Backyard-Astronomers-Guide-Terence-Dickinson/dp/0921820119

If you could tell me more about your budget and what is most important to you now that I've shown you a few options I could help you further. One last thing I always do in telescope threads is point people to the Cloudy Nights website. Lots of reviews and a huge community of helpful and extremely sharp and knowledgeable people. If there's something we can't answer here you are guaranteed to find an answer there. http://www.cloudynights.com/

wonderpug

Sarksus, a few years back I remember seeing some kind of program or whatever whose goal was to get more people interested in astronomy by providing either inexpensive telescopes or inexpensive kits to build your own telescopes. Could've sworn it was a reflector, but the memory is getting pretty fuzzy.

Ring any bells? Or is there some modern version of a program like that?

Sarksus

Yeah, during the International Year of Astronomy (2009) there was the Galileoscope project. They designed and made a telescope that was supposed to work like the telescope Galileo created himself. You assembled it yourself and learned how refractor telescopes worked. It was mostly made of plastic but the quality was actually pretty good, especially considering the cost. Back then they cost like $30 I think but since then the price has gone up unless you're buying in bulk. It's a very limited telescope but enthusiasts mod them (sometimes with hundreds of dollars worth of equipment for the comedy value) and they work nicely as a starting point.

https://www.galileoscope.org/gs/

Another IYA project was Celestron's FirstScope, which might be what you were thinking of actually. It's a small, cheap reflector that you sit on a table.

http://www.amazon.com/Celestron-21024-FirstScope-Telescope/dp/B001UQ6E4Y

DrZiplock

Holy crap, Sarkus.

That is phenomenal information. Thanks very much.

I'm obviously going to be doing a bunch more reading, but you've provided a pretty great jumping off point. I honestly had no idea where to start and yep...very helpful.

I think you're right, the GoTo mount is just out of the question. Besides, from everything I've read so far, the PushTo is actually better in a lot of ways, which is nice.

The price point on some of the Orions that you linked to is just about right. I was figuring that this was going to cost between $400-$600 depending on what was out there. The XT8i is particularly appealing right now. There's no current plan to do any photography with it, so that's not a concern and the finder that they have will be good to take a look at some nebulas and galaxys which are her particular favorite. Would the 6" still manage those with ease?

The calibration of the lenses has me a bit concerned. There is potential that this sucker is going to have to do some serious traveling within the next year and I'm sure that won't help with keeping things in line. Is is usually something that the owner can do or is that a rather special "send it out and you'll be better off for it" deal?

Sarksus

Oh no, sorry, I didn't mean to make collimation sound like a big job. The owner does the collimation themselves, it's not something you send the scope out for. You collimate it after it's been assembled and whenever you've moved it around a lot. Otherwise the collimation should hold pretty well and only needs to be checked.

The six inch is definitely viable and it has its own benefits. You might have noticed that telescopes have an F-number, like a camera. This is the telescope's focal ratio and it's derived from dividing the focal length by the diameter of the lens/mirror. So the 6XTi's focal length is 1200mm and its mirror is 150mm (5.9 inches). This gives you a focal ratio of 8. Focal ratio determines a number of things and one of those things, in the case of reflectors, is how forgiving the telescope is in regards to the collimation. The higher the f-number the more forgiving the telescope is and the more you can get away with a less-than-perfect collimation tune-up.

So the summary for the six inch is that while it's on the small side you can still see a good amount of stuff in it, it's very portable, it's forgiving for newbies who might not be good at collimation and also with a high focal ratio the amount of distortion at the edges of the field of view is virtually eliminated barring the usage of particularly horrible eyepieces.

The eight inch, in the interest of size, has a larger mirror of course but the focal length was kept the same. Longer focal length will result in a longer telescope. Since the mirror diameter has increased and the focal length has remained the same the focal ratio has gone down to about 6. This is still pretty forgiving and the distortion should still be non-existent. Eight inches is a sweet spot in my opinion. You'll be able to see nebulas and galaxies with the six but they'll be brighter in the eight.

I really like the Intelliscope series. I used to own one (I had a twelve inch but I had to get rid of it because it was simply too big to move easily). While you have to push it around yourself the dobsonian design is extremely simple and easy to use and you have the option of turning off the computer and using it manually if you or your friend ever want to learn the locations of objects yourselves.

Here is a link to what's called a sight tube. Orion telescopes come with a "collimation cap" to help you align the mirrors but it's difficult to use in my experience. The sight tube makes it easier and gives you a better alignment. http://www.telescope.com/Orion-Collimating-Telescope-Eyepiece/p/3640.uts

Shadowfire

I have an Orion 6" Dobsonian, and I'll speak to their quality. The price was reasonable, and the telescope is excellent. I don't have one of the computerized ones, though. I tend to just use my phone with Star Chart (way better than Google Sky) to find objects in a hurry, or if I have time to plan ahead, I use Stellarium on my PC. And I'll back up what Sarksus says about collimation.. I'm not very good at it, but we can still get some magic out of it. Also, if you want to look at the moon at any point, do yourself a favor and buy a filter. The first time we looked at the moon through ours we couldn't see without a blob in the middle of our view for a little while afterward. ;-)

Sarksus, do you have any recommendations for eyepieces? We'd like a better eyepiece than the one we have (the 1.25" 25mm one that came with it), but we're not even sure what to look at.

Sarksus

Depends on your budget. You can buy a passable eyepiece for as little as $50 or spend over $700 :P

This advice will benefit Ziplock as well so I'll be verbose: there are a few things to consider when buying an eyepiece. The most obvious is the focal length of the eyepiece. This is the millimeter designation you see. The shorter the focal length the larger the magnification. In order to derive the magnification you divide the focal length of the telescope by the focal length of the eyepiece. The amount of magnification you can use without the image degrading is dependent on the diameter of the telescope's objective (the mirror or lens the telescope uses to gather and bend the light).

Generally the highest magnification is for every inch of diameter of the objective you can get 50x magnification. This is an optimistic figure that will only be true when the seeing conditions are very good but it's a good guideline to follow. If you go above this you'll be wasting your money under most circumstances. So for a six inch, for example, your theoretical maximum magnification is about 300x. To get the focal length of the eyepiece which will give you this magnification with a six inch telescope that has a focal length of 1200 (like the Orions do) you divide 1200 by 300 and get a 4mm eyepiece. You don't want an eyepiece that has a shorter focal length than this in the case of the six inch Orions. Just because you can go this low doesn't mean it should be your first eyepiece, however, and I'll explain that later.

Other things to consider about an eyepiece is eye relief and apparent field of view. Eye relief refers to how far your eye can sit from the eyepiece and still see a clear image. Long eye relief is good for comfortable viewing but is especially sought after for those who wear glasses. Eye relief has never been a concern for me as I don't need to wear glasses while at the eyepiece so I don't really have good recommendations for a preferred eye relief. Apparent field of view basically refers to how much stuff you can see in the eyepiece. 50 degrees is considered low, 65 will about fill your eye I think, and then there are 82 and 100 degree fields where you will actually have to look around inside the eyepiece to see everything. This is meant to give you the feeling of being in space. The larger 82 and 100 degree eyepieces are usually more expensive.

Now, for actual recommendations. Luckily there are a lot of great eyepieces out there and even the cheaper ones can give you pretty good views. Actually, a side-note, the "slower" the telescope, that is the higher the f-number, the more lee-way you have in eyepiece selection. You can get away with the cheaper stuff and it'll still look okay. For example, the Orion Expanses are around $50 and should look okay in a six or eight inch telescope. A larger telescope will usually have a smaller f-number, meaning it is "faster", and the Expanses will begin to look worse. A telescope, like a long refractor with an f-number above 10 would look even better. The Expanses also have a 66 degree apparent field of view so you won't feel boxed in. There are also the Orion Stratus eyepieces which have the same field of view but the quality is supposed to be higher. They are also more expensive, of course, at a little over a hundred dollars.

If you can spend more money on eyepieces a safe bet is always on TeleVue. They are more expensive but they have a full range of options and they're top performers. The basic eyepieces start at around 80 and the more specialized and better featured eyepieces can climb up past $700. They are serious business. Personally, the Stratus and that price range are the lowest I would go but if you still need to go lower you won't be totally screwed with eyepieces like the Expanses.

There are of course lots of other options. If you want to learn more you could go to the Cloudy Nights forum and search their eyepieces sub-forum. They know a lot more than I do and could give you more recommendations if you make an account there too.

One thing you might consider is what's called a "barlow". A barlow essentially increases the magnification of any eyepiece you slip it into. Usually it doubles the magnification but there are also 3x barlows. The barlow decreases the focal length of the eyepiece, so a 10mm becomes a 5mm, for example. This nets you two eyepieces for every one you've actually bought. Orion and TeleVue both make good barlows. TeleVue will be more expensive, of course.

Shadowfire, for your six inch, since you already have a 25mm a higher-power eyepiece would be good. Something around 12-15mm would be good if you also got a barlow. If you didn't then a 6-8mm would also be good so you could get some higher magnification out of your telescope. I wouldn't recommend jumping straight to your highest possible magnification because as I said you'll only be able to take advantage of that under the best conditions. There is also a balance to strike between being able to see at high magnifications and the flexibility and wider field of view of a lower powered eyepiece.

DrZiplock

Sark, you are a phenomenal wealth of knowledge. Thank you.

Yea, the 6 and the 8 inch models are still very high in the running. A lot of it depends on where we'll be in the next few months. If it looks like we're staying relatively still then I'll likely end up getting her the 8. If we're moving (and it would be a big move) then it'll probably be the 6. We'll see.

Good info about the eye pieces as well.

I'll keep you posted as I develop more questions, etc. Of course I'll let you know what I end up buying as well.

Sarksus

Yeah let me know. For what it's worth I don't think the eight inch would be too difficult to move, especially when the scope is separated from the mount. Good luck. I hope you have a good time with it.