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 Celestron Powerseeker
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DrakeXV
 Monday, September 27 2010 @ 11:47 am EDT (Read 6314 times)  
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dgrosvold
 Monday, September 27 2010 @ 02:38 pm EDT  
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Hi Drake -

Have you ever used a telescope before? These are both on German Equatorial Mounts, which take quite some time to learn to use effectively.

It looks like your budget is fairly low, but if you can swing it, and if you have not had any experience with a telescope, I would highly recommend something like this instead:

Orion StarBlast 4.5 Reflecting Telescope

I believe you will be far more satisfied with your purchase than you would with one of the ones you listed.

If the one I listed above is out of your price range,t hen you might want to consider this one instead:

Orion SkyScanner 100 Table Top Reflector


Dave - Morrow, AR
 
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DrakeXV
 Tuesday, September 28 2010 @ 03:52 pm EDT  
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right now i've got a friend's department store reflector and i'm looking for something under $300 to play around with. but, i wasn't aware the eq mounts were difficult to use. honestly i'll probably end up getting a small dob like the orion xt8. but i've had this 60mm for a while now and i want to get a real scope soon. nothing special, just something to keep me going until i can save up for something nice.


 
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Burningmic
 Tuesday, September 28 2010 @ 07:42 pm EDT  
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I've been looking online a lot for a good deal on telescope. Whats the cons of the GEM telescopes? I almost bought one today but suffer from preemptive buyers remorse. I've looked a lot at the Reflector Telescopes as well. They seem easily portable but awfully small all at the same time. What are the pros?


 
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dgrosvold
 Wednesday, September 29 2010 @ 03:12 pm EDT  
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Quote by: DrakeXV

right now i've got a friend's department store reflector and i'm looking for something under $300 to play around with. but, i wasn't aware the eq mounts were difficult to use. honestly i'll probably end up getting a small dob like the orion xt8. but i've had this 60mm for a while now and i want to get a real scope soon. nothing special, just something to keep me going until i can save up for something nice.


DrakeXV, I didn't say the EQ mounts were difficult to use, only that they have a steep learning curve. For a beginner, starting with a non-go-to EQ mount, it can be enough to drive you right out of being an amateur astronomer altogether. The problem is, you get into having to grasp things like polar alignment, manual setting circles, concepts like right ascension and declination, drift, and so forth. This is before you ever get the scope lined up on a star.

I don't want to denigrate Celestron products, but the ones you linked to are the very bottom of the scale. The quality of an EQ mount such as those sold with a small 114mm scope is that they can't be very high in quality due to the basic economics of manufacturing, and they will be ultra-light weight as well (read that as "rickety".) You will have nothing but frustration with such a contraption. On top of that, the EQ mounts you picked do NOT do anything in the way of finding objects. They simply track them AFTER you have spent the time to find the object yourself. So I don't see any advantages to these at all.

On the other hand, with the scopes I recommended, you can set the thing on a table, point it at something and be observing in just a few minutes. A 4.5" Newtonian Reflector telescope will show you plenty of good things - the Moon, the planets, and lots of the brighter deep sky objects.

You've obviously learned some of the sky already with the 60mm scope you have, but a 4.5" reflector will show you way more than the 60mm, and it costs so little that you can save the rest of your funds for a better scope. If you can afford it, I would have to agree that the Orion XT8 would be an excellent choice for the money.

When you get ready for an EQ mount with an 8" or larger scope, then we're starting to talk about spending a few dollars. The very MINIMUM EQ I would ever recommend would be the Celestron CG-5 or Orion SkyView EQ Pro, and even these are too small for an 8" scope. These both are the smallest EQ mounts with go-to capabilities, and I would NOT recommend getting a mount without go-to these days. At this point, we're taking about $1000 or more for the minimum go-to EQ mount with a small 6" Mak or Newt scope.


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dgrosvold
 Wednesday, September 29 2010 @ 03:16 pm EDT  
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Quote by: Burningmic

I've been looking online a lot for a good deal on telescope. Whats the cons of the GEM telescopes? I almost bought one today but suffer from preemptive buyers remorse. I've looked a lot at the Reflector Telescopes as well. They seem easily portable but awfully small all at the same time. What are the pros?


What's a good deal? I bought a 8-year old 12.5" Dobsonian mounted reflector last year for $1200 and with the accessories and high quality TeleVue eyepieces I got with it, I know I got a great deal on it! This spring I bought a 4" refractor, and a nice Alt-Az mount, wooden tripod, etc. and sunk about $2000 in it. Very nice views. It's still a good deal, to me. It depends on the quality of the pieces and your intended purpose. If you spend $144 on eBay, get the thing home, spend a few evenings struggling with it and then shove it in the back of a closet have you made a good deal? Get the best you can afford. If you can't afford it, maybe waiting until you can is preferable to having junk you can't use.

As far as GEMs (EQ mounts) go, there are GEMs (non-go-to) and there are GEMs (go-to.) The cons of cheap ones I've already covered above. More expensive ones, and you're playing in a totally different ballpark. The Celestron CGEM or Orion Atlas EQ-G are both a little more than $1300 without a scope, but you can start with one of these and with the computerized alignment routines, you can get up and running much faster. Add a decent 8" or larger catadioptric scope, 8" newt, or a 4" refractor, and you're easily above $2500 territory. Even these mounts are a bit small for an f/5 Newtonian scope above about 8".

Wanna talk about the pros and cons of each kind? That's been done to death already. But here's some food for thought:

Construction/Quality/Cost -- Reflector telescopes offer much larger aperture for the same money than refractors, with very little loss of contrast. Remember the typical Newtonian reflector has 2 optical surfaces that require precision grinding, and only one of these involves a curved surface. A doublet refractor requires 4. A triplet refractor requires 6, and these are all compound curves. Even a Schmidt-Cassegrain only has 3 curved optical surfaces to worry about, so that's why they're still cheaper than refractors - much cheaper if they're the same aperture.

Of course, you can get anything too cheap. But for a modest sum of money, you can have a VERY high-quality Newtonian system of medium aperture or larger. The Chinese have learned to make sub-$1000 instruments that rival the very best handmade instruments of just a few decades ago. And like most things, the quality of hand made products has also risen, though at ever-increasing cost. A high-quality 12.5" Newtonian Reflector on a Dobsonian mount from a custom manufacturer can run to $4K - $5K or more. For a custom, hand-made 12.5" Corrected Dall-Kirkham (a type of reflector,) it's more than $10K just for the optical tube assembly - no mount. That same money might only buy a 6" triplet refractor (OTA only.) Even higher, how about a 12.5 inch f/9 Ritchey-Chrétien for $21.5K? The sky is the limit!

The Observing Experience -- Refractors have very high contrast views, but always with some chromatic abberation. Visually it's usually not a big problem, but it can be for advanced astro-imaging. Of course, triplets and even complex four-lens objective elements can minimize this. Great for planets and lunar studies, or in the more expensive ED doublets and triplets, excellent for wide-field deep sky astro-imaging. A high-quality refractor deserves a high-quality mount, so be sure to factor that into your budget.

Reflectors have lower contrast, but that can be overcome by using MUCH larger aperture. The problems inherent in reflectors appear in the form of cool-down times, spherical aberration, coma, tube currents, etc. However, these can all be minimized or compensated for with the addition of accessories and/or design tweaks. The hardest thing to overcome in a reflector is sheer physical size.

An Orion XT8 will fit in the back seat of my full-size car, with the mount in the trunk. However, that reduces the number of other things I can carry, and only one passenger. My 12.5" Dob requires a full-size truck, and two people to lift it. However, a truss-tube style Dobsonian reflector breaks down so small it can fit in a small car, such as a Honda RAV4.

The other problem is, the mirror/rocker box combination of a 12.5" truss-tube Dob can weigh nearly 100 pounds. Two people can lift it into the back of a car, but if you live in an apartment, do you really want to lug that down two flights of steps every time you want to observe? Even the much smaller and lighter XT8 can become a burden in that situation.

20 years ago, I lived in a 2nd-floor apartment with an 8" Schmidt-Cassegrain, and I was able to lug it and the fork-mount plus tripod up and down the stairs, but I had a half-ton pickup to carry it, and that was when I was in my early 30's. I wouldn't want to even try dealing with a truss tube dob in that situation. Now, I enjoy lugging my 110mm refractor, the small alt/az mount and light-weight tripod to star parties. The 12.5" dob stays here on the ranch, and I can use it without having to haul it in a truck, even though I have one. No lifting.

Well - I hope I've given you some food for thought. My best advice? If you only have $150 to spend, get a pair of 7 x 50 binoculars and a chaise lounge. If you have the budget (roughly $500,) get an 80mm refractor on an Alt-Az mount or something like the Orion XT8 and start observing with it. Unless you have unlimited time, you will not be able to exhaust the number of objects you can find in the night sky with one of these - probably for several years. If you have more money ($1500,) get a go-to mount and a better scope. You will see more and you would even be able to dabble in astro-imaging later on. Note that I said "dabble." Advanced astro-imaging requires a much larger investment of not only money, but time as well. If you have NO money, go to star parties and look through the members scopes.

Anyway, that's my $0.02. Other astronomers may disagree.

Edited 9/30/2010, 12:24 AM CDT


Dave - Morrow, AR
 
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Burningmic
 Wednesday, September 29 2010 @ 10:04 pm EDT  
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Thank you. That was very helpful. I think you just talked me into saving some money to buy up instead of jumping at something cheaper . I am very interested in dabbling in some astrophotography. The wife has been researching cameras and is thinking about a Canon but that sets us in the same boat, saving up for the good one. It looks like $900+. I plan on coming to the Star Party. I figure it will help me know more about what I'm actually 'looking at" with different telescopes.


 
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DrakeXV
 Thursday, September 30 2010 @ 10:38 am EDT  
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yes, thank you dave. very insightful.


 
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