Since Galileo began observing celestial objects with a telescope, an almost uncountable number of improvements have been made to his designs and methods. Telescopes can now view anything from radio waves to gamma waves, come in a wide range of sizes and shapes, and some are also fairly accessible to hobbyists as well. In fact, several homemade telescopes are specifically designed for ease of use, portability, and minimum cost, like this portable ball telescope. (Google Translate from Italian)
The telescope was designed and built by [andrea console] and features a ball-shaped mount for the mirror which was built from a bowl. Ball designs like this are easier to orient than other telescopes since the ball allows for quick repositioning in any direction, but the main focus of this project was to investigate focal length with various accessories while also being as portable as possible. To that end, the mount for the eyepiece is on a lattice that assembles and disassembles quickly, and the ball and other equipment are easily packed. This makes transportation quick and easy and reduces weight compared to a more traditional, or even Dobsonian, telescope.
This build is impressive not just from having an extremely portable telescope, but also from [andrea console]’s documentation of the optics in his build. It includes some adjustable parts which can increase the magnification and has detailed notes on all of the finer points of its operation. The ball telescope is a popular build, and we’ve recently seen others made out of parts from IKEA as well.
Looks like a really clever way to build a mobile telescope. My experience is that after assembling telescope on site one needs to realign optical axis of prmary/secondary mirrors. I wonder how it’s done in this design.
Also since the focal lenght/telesope height is relatively small here I guess the scope could benefit from an equatorial plate to help following stars as the sky rotates.
All in all though it’s a cool project!
realignment is quite easy with the correct tool (cheshire and/or barlowed laser cheshire).
The main issue with these small portable telescope is their low height when pointing bellow 45 degrees.
For the most compact and portable scope, look for Strock 250. Completely open source and quite successful.
Yeah, realignment is pretty easy with those tools. Only discovered them recently. Wish I’d invested years ago! Started astronomy as a hobby when funded by pocket money and Christmas presents. Lasers weren’t affordable back then.
i assume practice makes perfect and over time you get good at collimating the thing :)
Hi! First of all, thank you for your kind words. The telescope has the classical three screws for the secondary mirror and two big knobs for the primary (easily accessible from the front). After adjusting the secondary at home, aligning the primary on the field takes not more than a couple of minutes (also because it requires only minor adjustments). Clearly, you need a tool for this (I used to use a barlowed laser, but with the Reego collimator I’m even faster). Coming to your second statement, one benefit of the ball-scope configuration is that you can easily build a motorized equatorial plate that does not have an initial and final position like the ones you use with common dobsons (see http://telescopelemay.com/language/en/inventing-the-ball-scope-tracking-platform/ ). Anyway, I prefer to have no electronics at all to bother me when I’m stargazing :) (plus I use wide-angle eyepieces and I don’t need high magnification for galaxies).
Thi design has been around for a while and I contemplated making one with my 8 inch (20 cm) Newtonian. In fact, years ago someone took a 150mm mirror and put it inside a commercially available sphere from a table lamp. A similar design can be found here. https://en.wikipedia.org/wiki/Infinite-axis_telescope
All in all, looks like a neat design by the author.
Hi Ettore, thank you for you kind comment. When I chose to build a ballscope, I was looking for something cheap (thank you Ikea for providing a cheap and strong steel bowl!), easy to build (not a good diyer here), easy to operate (I would never go back to a traditional dobson – insert easy dirty joke here – and it is ready for use in few minutes, as you can see!) and compact. Unfortunately, ball scopes are usually quite bulky with respect to the size of the primary mirror. The tilted configuration I used and the particular design of the tube allowed me to achieve also the latter objective, so that I could bring my scope under the dark sky of the Canary Islands just with a single regular piece of luggage (and the primary mirror in my hand luggage).
Thank you for featuring my ball scope on Hackaday, this is quite an achievement for me!
A particular feature of my design that is worth mentioning (and that I’ve never seen so far anywhere else) is the tilted primary mirror (with respect to the bowl). This design allows to use half-sphere instead of 3/4 of a sphere and still be able to reach low elevations. The balancing of the telescope is perfect if the eyepiece is not too heavy (my heaviest eyepiece is around 700g and I use a Rigel finder, which is particularly lightweight).
Reminds me of the little Ball Scope sold by Edmund Scientific a long time ago.
Yes, and I gather that was one of the most sold telescopes ever.
I wonder if a challenge with this type of design is that you need the ball to roll easily enough to manoeuvre, yet rigid enough to not accidentally move when you look through the viewfinder?
As far as I know, this is the challenge with all telescopes without a motorized mount. However, I must admit that, with this design, the challenge was way easier than expected: no teflon required, just some velvet on the circle of contact between the base and the bowl. Perhaps it may be a little stiff at higher magnifications, but I usually don’t go above 200x.