Wednesday, August 07, 2013

The Smaller Telescope, Pt. IV - Examples of Current Smaller Telescopes

There are plenty of small telescopes out there, but the buyer needs to beware; too many of them are really not good telescopes at all. It's not optics alone that make a telescope. There are two other items that need to be as important; the mount and the accessories, namely the eyepieces.
One of the most common telescopes is the 50mm. If you go to eBay, you will find hundreds of them, with a solid proportion of them being sold with the flimsiest of mounts. Even the big names, like Meade or Celestron, have been known to drop the occasional bomb.
What follows is based upon personal experience. 

  • Meade Jupiter Series 50mm - 

This telescope has been out of production for a few years, but there are still plenty of them around. Like most 50mm, its primary lens was just fine. The problems arise when we move beyond the telescope. The first big problem was the tripod. It was somewhat wobbly. Since the telescope had a threaded mount, one would expect that you could simply replace the tripod. That is where we make the discovery that not only is the mount "stepped', it isn't a standard 1/4"-20 thread, but something close. The diagonal and eyepieces were .965" standard. These days, I keep an open mind, as there are good .965" eyepieces available. These were marginal at best. You could purchase a hybrid diagonal and move to the more common 1 1/4" size for eyepieces, but then the problem with the tripod still exists. I did not keep the telescope long.
Conclusion - wasted potential.

  • Meade 60mm AZ-T - 

Another one from Meade, and again also out of production. This telescope is a short tube tabletop model. It has quite a bit of plastic, but is not that bad a little instrument. It comes with an erect image diagonal, two 1 1/4" eyepieces (a 20mm Kellner, and a 9mm MA; mine had a 17.5mm MA instead of the 9mm!), a Barlow and a tabletop tripod with standard 1/4"-20 threads.  Sold with a handy carrying case. This is one of my favorite telescopes. Some people have complained about the focuser, but I've not noted any difficulties with mine. A great little "grab-n-go" telescope, it provides really nice views. The included Barlow was the only fault I could find with this telescope. I normally mount this on a heavier, and taller, tripod. I have managed to get a fair chunk of Messier's list with this telescope, even with the modest 17.5x magnification the 20mm Kellner provides. These are still to be found online at reasonable prices, and is recommended.

  • Galileoscope - 
This is the much vaunted 50mm educational telescope. When you purchase it, you are provided with just a telescope, and its accessories, all of which you assemble. The main eyepiece is a 20mm Plössl-type design, which for having plastic lenses provides very nice images. The other eyepiece is a Galilean, that is to say, a single concave lens, which also serves as the base for the 2x Barlow. Both are 1 1/4". When this telescope was announced, the initial plans was for it to cost $15 USD. It has now more than doubled, but is it worth it?

In my opinion - possibly. As an educational tool, it's great. It provides the student with hands on experience of how refractor telescopes work in their most basic form. The telescope comes equipped with a 1/4"-20 thread mount (really, a nut which is held into place in the lower part of the optic tube), so commercial tripods can be used. The Galilean eyepiece allows the student to see the sky the way Galileo did. However, there are downsides to the design as well. The optic design is straight-through; it cannot take diagonals. Well, it can, but the resulting focus range is very tight, depending upon the diagonal used. So, the telescope needs a fairly high mount; most recommend a tripod that can extend to 60" (1.524 m), as well as a chair or seat of some sort to make viewing higher objects easier. Objects that are closer to zenith, though, will be extremely difficult. 
Optically, it is a nice telescope. As stated previously, the 20mm Plössl gives good view when combined with the 50mm primary, I've used other eyepieces, and objects closer to the horizon, and feel that the telescope works fine.
Recommended with caveats.

  • Celestron FirstScope 76mm "baby Dobsonian" - 

I purchased this telescope in the spring of 2013, and am really surprised by its performance. It is a small Newtonian in a one armed Dobsonian mount, comes with 1 1/4" eyepieces, and is one of the easiest telescopes to work with right out of the box; open it up, set it on, say, a picnic table, remove the focuser and dust cover, pop in an eyepiece, and you're set. 
It does have weaknesses. For one, the included eyepieces are not the best. Of the two, the 20mm MA is the more serviceable, while the 4mm Huyghens is really not that great at all. Lack of a finder scope might bother some people. The primary mirror cannot be collimated (adjusted). 
But, how does it perform?
Ignoring the 4mm  eyepiece, with the 20mm MA it performs fine. The focal length of the telescope is 300mm, so it is a true short tube Newtonian, and operates better at low power. Still, moving over to one of my other eyepieces (a 10mm MA) revealed a great image of the Moon. 
My recommendation - probably one of the better beginner telescopes out there (along with the very similar Orion FunScope, based upon reviews and comparisons written elsewhere). Just purchase some additional eyepieces, maybe a finder scope, and you should be set.

To close, just a thought. Occasionally, you can find cheap telescopes at thrift stores and yard/tag sales. If the price is low enough, don't be afraid to purchase the instrument and give it a shot. There are always diamonds in the rough. Just keep in mind that some work might be needed, but the process of making those improvements simply add to learning more about this wonderful endeavor we call astronomy, If, in the end, the instrument is still found wanting, at least that can be said.

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