In My Search for A Good Telescope I found This. Can someone answer a few things about it?

Question

Hello,

I have seen this telescope:

http://www.telescopeplanet.co.uk/ViewProdDetails.asp?prod_code=PON07B000186

I was wondering if this seemed to be of a high quality, and if i would be able to see high deatails, for example saturns rings with it, even in a light polluted town??

It says it is motorised, what does this mean? Is it that when it has a database of objects, and you can selected certain ones, such as orion nebular, and it will automaticly point there for you?

Help would be nice!

Thanks.

As a point of interest, I have found a similar telescope, just with a 130mm aperture. I would also like info on that if possible.

You can find more info here:

http://www.telescopeplanet.co.uk/ViewProdDetails.asp?name=Skywatcher%20EXPLORER-130PM%20Motorised%20Parabolic%20Telescope&prod_code=PON07B000059

I have to also point out, in regards to some posts saying that it is poor quality, This cope has been the winner of some BBC Sky At Night Group Tests, so surely this can't be THAT bad.

Answer 1

Yes, that appears to be a good quality telescope. You could easily observe the moon and all the planets and see the rings of Saturn. One way to tell a good scope is if they don't exaggerate the magnification than can be used with the scope, as this one doesn't. Most planetary observing is done at 100x to 200x (which this one would have when you use the 2x Barlow).

Motorized in this case just means that once you center the object in the telescope, the mount will follow the object without you having to touch the telescope and you can move the telescope by motors instead of by hand. This does make for easier observing once you center the object. But it is harder for a beginner to find an object without a go-to computerized mount, which this is not.

The other problem with this type of telescope is that you need to align (collimate) the mirror and lenses to keep the telescope in peak operating condition. This is not too hard once you do it a few times but does take practice. That's why most beginners go with a Schmidt-Cassegrain computerized telescope which costs more.

However, the moon and most of the planets are easy to find in the finder scope so this telescope should be fine for your needs.

Answer 2

With either of these telescopes and the proper eyepiece you will be able to see Saturn and it's rings, but not close up unless viewing conditions are calm enough, and the equipment is good enough to permit you to use very high magnification.

Telescopes do two two things. They brighten by collecting light, and they magnify with the help of an eyepiece.

Most things in space are dim, not small. To see a galaxy, for example, you generally want a large telescope that can collect a lot of light to make the galaxy very bright, but you want a fairly low powered eyepiece, or the galaxy won't fit in the field of view.

Planets, on the other hand, are bright, but small. To see detail on them, you need to use high magnification. The magnification you get is decided by the focal length of the telescope and the focal length of the eyepiece.

Magnification = (telescope focal length)/(eyepiece focal length)

You can see that the longer the telescope focal length, and the shorter the eyepiece focal length, the more magnification you will get. BUT there's a catch or two or three.

On a very good night, the highest practical magnification you can use is calculated to be 50 times the aperture of the telescope. So for this reason, larger telescopes generally outperform smaller ones for planetary viewing. You don't need that extra light the larger telescopes collect in this case, you may want to use an aperture stop or filter to limit the amount of light coming in.

These two telescopes you are looking at don't have GOTO, they have motor drives. This means that, if they are set up correctly, they will follow objects across the sky. Otherwise the objects would "move out of the field of view" due to the rotation of the Earth.

This telescope isn't the best telescope but it's probably not the worst either. It will probably give you some thrills and you will be able to see things but there are better ones out there for the right price.

If I were you, I'd try to get the largest telescope I could afford.. If I wanted to view mainly planets, I'd go for a longer focal length than shorter. If I wanted to do astrophotography or have things stay in the field of view, I'd get one with a sturdy, metal german equatorial mount. If I wanted to just look through the eyepiece and focus mainly on galaxies and nebula then I'd forget the german equatorial mount and buy a dobsonian.

In either instance, I'd buy either a Celestron, Meade, Orion, or maybe a Zhummell. I might buy a Konus or definatly a Cave Astrola if I could find one. I'd probably buy the telescope used, because I'd get more for my money that way.

If I couldn't afford a telescope with at least 8" of aperture then I would NOT get one with a goto system because why goto 25,000 stars when they all look the same, or 4,500 objects that the telescope isn't large enough to see?

I hope this helps. Remember. Lots of aperture, sturdy mount, quality 2x barlow.

Answer 3

Sir:

The telescope you pointed out in your first reference has a four and one half inch mirror inside which is the working part of the optics. That mirror is not very big. The bigger the mirror is the better it will work for you, assuming the optical quality of the mirror remains constant.

I recommend that you look not at 4 1/2 inch mirror scopes, but rather at 8 inch mirror scopes if you want to see good
views of objects in space. The next step up from that is the 10 and 12 inch mirror reflector scopes, and those get really big. The view one can get from them is really great. So, Reflector scope Models with at least 8 inch mirrors is about the floor for pretty good scopes. To place this in perspective,
four and a half inches is about the size of a baseball. Eight inches is about the size of a small diner plate. Ten and twelve inches is about the size of a large diner plate.

The mirror mounts in the bottom of a large, hollow tube. The eye piece mounts on the side of the tube and sees via a mirror mounted inside of the large tube which looks down into the large mirror. The eyepiece mounts into a focuser assembly which allows for minute adjustment of position for the clearest possible picture.

The big tube of a reflector telescope must mount in some kind of holder to keep it steady. Inexpensive holders are called dobsonians and are relatively fixed which means that the stars and planets will sweep across the viewing window over time. Motorized mounts have gear drives which move the scope ever so slowly in time with the rotation of the Earth so that your viewed picture stays fixed. Some computer driven mounts have the information on location of various stars and planets stored on memory chips within the motorized assembly. With certain models it is possible to
key in the identity of a certain star and have the scope automatically point to it once the scope is correctly oriented. This set up takes a few minutes, and if left alone, will last for an evenings viewing. Do not leave your telescope out over night, or permit rain and dew to fall upon it.

Answer 4

Those are made in China, and were it not for the parabolic mirror I would say, stay as far away as possible. Since it does have a parabolic mirror (not a spherical mirror with a corrective lens), it might be barely acceptable as a telescope.

If all you want to do is look at planets, the moon, maybe some of the larger more defined nebular objects and galaxies -- this scope will do OK. I would go with the 130 mm mirror, though.

I bought one of these (a 150 mm spherical mirror) and it was a piece of junk. I re-built it with a decent mirror, but even now the motor does not turn the gimbal in the mount. Maybe with a factory installed motor (mine was an add-on) yours will work better. At least I have a good equatorial mount -- that's about all my original kit was good for.

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Answer 5

You will definitely be able to see Saturn's rings.

This telescope is not bad for its price range, which is low. If you can afford to spend a little more, i would recommend moving up to a 6" refelector (this one is 4.5"), which will give you significantly more light-gathering power.

The motor drive means simply that, if you align the telescope properly, it will track the apparent motion of the object in the field view (i.e. it compensates for the Earth's rotation). There are many telescopes that come with the type of computerized database that you mention, but it does not appear that this one does.

Answer 6

About 4 years ago I bought a very similar one for my grand daughter ,but was very disappointed because they live in the edge of a large city and often it is humid and the city lights just blind u. Good luck