Galileoscope eyepieces

Galileoscope co-designer Stephen Pompea peers through his creation. (Dean Coppola)

“I put my Galileoscope together. How do I use all these eyepieces?”

That’s a question I get all the time. There are three different eyepieces depending on how you assemble the components:

There are three eyepieces for the Galileoscope depending on how you assemble the components.
Creative Commons License Galileoscope eyepieces photo-illustration by Peter Newbury is licensed under a Creative Commons Attribution 3.0 Unported License.

The easiest way to use your Galileoscope is with eyepiece A. It gives a fairly widest field-of-view (you can see the largest region of the sky) with a 25x magnification. This is the combination I recommend to new users, parents and kids, and school groups. With this eyepiece, you can easily see the craters and shadows on the Moon and the moons of Jupiter.

The combination A+B+D gives an eyepiece with 50x magnification because B+D create a Barlow lens that doubles the magnification. The increase in magnification comes at a cost: a much smaller field-of-view and fainter image. It is almost impossible to use this 50x combination without a tripod (which the designers anticipated by building a nut into the bottom of the Galileoscope that fits any standard camera tripod.) If you have a tripod and a clear, dark skies, you can see the rings of Saturn. Yes, the rings of Saturn! And that’s magical.

Finally, there is a special lens combination included for historical (and educational) reasons. You see, the Galileoscope was designed as a cornerstone project of the 2009 International Year of Astronomy (IYA2009). That celebration marked the 400th anniversary of Galileo using his telescope to observe the Moon, Venus and, in 1610, the moons of Jupiter. The special “Galileo eyepiece” C+D mimics the view Galileo had, with a meager 17x magnification over a tiny field-of-view. The image appears right-side-up, though, unlike the 25x and 50x combinations which invert the image as most refracting telescopes do.

With all these eyepieces and magnifications, I still recommend the simplest one, just the 25x. In fact, when I’m doing “sidewalk astronomy” I keep the Barlow lenses in my pocket and pull them out only with the more advanced telescope users. Going from naked-eye to 25x already opens up a Universe of wonders.

Parents, teachers, sidewalk astronomers: The Galileoscope design team has put together a great collection of resources. You can order Galileoscopes directly from them, from Learning Encounters or check your local telescope store.

I’m really interested in learning to take pictures through my Galileoscope. If you’ve taken some good ones and have any tips, I hope you’ll share them below.

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