[Physics] What can be seen with a 114mm Aperture 675x Zoom Telescope

astronomytelescopes

I choose to post this question on the physics exchange seeing there would be a bigger audience for answers than the astronomy exchange still in BETA.
But i'm looking to buy a telescope and was wondering what i could see with a 114mm Aperture 675x Zoom Telescope? The type of things would be interested in would be our planets their moons, comets hopefully and even very bright galaxy's if possible.

Best Answer

This really doesn't belong here, but I will answer anyway, because I don't like to see people being ripped off by the kind of cheap toy telescope that you seem to be referring to (at least that's what showed up when I entered your description into google). The sad reality is, that you can't see much of interest beyond the moon, and even that is, IMHO more enjoyable with cheap binoculars.

I bought one of these toys a month ago for \$10 at a thrift store to get a first hand experience of the "quality". To be honest with you, I was disappointed even for \$10.

The only useful eyepiece that came with the "instrument" was the 20mm. Given the focal length of the primary mirror of approx. 600-800mm, the effective magnifications is approx. 30-40. That's it. Even the 12mm eyepiece was, in my opinion useless and I couldn't properly focus the 9mm and shorter ones, at all. I never tried the 2x focal length extender... it would be a waste of time. So forget about 625 times magnification... that is more than beyond the useful range of even the best instrument with 114mm aperture. Anything above 100 times magnification is complete nonsense, not to mention that you couldn't find what you are looking for without a precision mount to begin with.

Now, since I also own other optical instruments (for professionals), I matched a low quality 25mm wide angle microscope eyepiece to the instrument (that's approx. a $25 investment, if you don't have one of these laying around). This made the telescope both more enjoyable and more useful. The moon appears in reasonable clarity now and I actually like pulling my Frankenstein out of the garage to look at it for a couple of minutes occasionally. As for a real telescope eyepiece, they won't fit, because the plastic eyepieces on this toy are approx. 1" in diameter, while the smaller amateur eyepieces are 1.25", if I am not mistaken. At the very least you would need an adapter.

Mars is not resolved, except as a tiny disk, and the coma is horrible, even after adjusting the primary mirror, which was screwed in so tightly, that one could see it bending visibly. I loosened the mirror mount but didn't take the time to adjust the optical path perfectly, since the primary mirror has visible coating problems and scratches around the rim, so I figure that it's nowhere near the right shape, anyway.

Saturn shows the slightest hint of a girdle, again barely distinguishable from the instrument's optical errors. I didn't have a chance to look at Venus, yet, but I don't expect to see much more than a hint of its phase, either. Jupiter's moons should be visible, but they can be seen with binoculars and it's easy enough to take a good photo of them with a 150mm or so zoom lens on a low end DSLR, so you don't really need a telescope for that.

The other day I looked at the Andromeda galaxy. Even though I know how to find it with naked eyes, it took me about half an hour to get it into the view of the instrument, since the finder scope is too dim to see it in there. You are basically tapping around blindly across the sky... until you are lucky to hit what you are looking for, assuming that it has distinguishable features. Well, Andromeda looks like a mere wisp, even in my wide angle Frankenstein eyepiece (I wouldn't expect to see it, at all, with the eyepieces that came with the scope). All one can see is the galactic core, there is no hint of the spiral galaxy structure. For comparison, I can clearly see the spiral galaxy in digital camera images using a simple tripod, a 50mm lens and 10-30 seconds of exposure time.

A very motivated amateur astronomer might be willing to look for things that are less luminous than Andromeda, but I think that Andromeda will be the one and only deep space object I will ever see in my toy, it's just too hard.

So where does that leave you? If you listen to me and everybody else who ever wrote a basically indistinguishable critique of "toy catalog telescopes", it will leave you about \$79-99 richer. If you want a telescope badly, the cheapest ones worth any money are probably 8" Dobsonian "light buckets" for approx. \$400. They are just what the name implies: an 8" primary in the lowest grade of mechanical mount that makes them useable for magnifications in the range of 30-100, or so. They are bright, have a wide field of view, and you can learn how to navigate the sky with them.

If you want to trade the size of the primary against the mount, you can go with a smaller aperture and a higher quality mount. Meade sella "better" versions of the aforementioned toy telescopes for around \$200, but I wouldn't spend that money, either, but save, at least \$400 for the next level up from there.

Even better, if you can find an amateur astronomy club, you may be able to look trough instruments in the \$10k price range that are owned by your new club friends. That will give you a much better idea of what can and can not be done with visual observing, even for a lot of money. If you can stand the disappointment, that Andromeda doesn't look nearly as magnificent as trough the focal plane array of the Hubble space telescope, then amateur astronomy may be for you!

Good luck!