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  #1  
Old 08-10-2018, 09:53 AM
N1 (Mirko)
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Galileoscope

The Galileoscope is a discontinued entry-level refractor developed for the International Year of Astronomy 2009 and was meant to give people on a tight budget a means of making celestial observations that go beyond naked-eye. It's a 50mm, f/10 achromat of decent quality, although the objective (besides the built in nut that attaches the tripod) is the only part that is not plastic or rubber. It uses 1.25" eyepieces. It's no longer available new, but can be picked up cheaply on the net from time to time. I got two for $40 NZ earlier this year and played around with them. The experience has been so good that I've decided to start this thread and occasionally record some observations of and with a telescope that is all to easy to dismiss as a toy based on its specs and materials used. The scope has been covered on here before, but hopefully I can add to that info rather than just repeat it.

With two of these, it will be nice to see whether some mods made to one have a tangible effect. So I started by giving the objective of "Unit A" a clean and flocking the inside (it needed it badly) using self adhesive fake velvet bought on Aliexpress for a few dollars. Note that flocking may not always be a good idea, but with such low stakes who cares. The immediate result was an improvement during daytime use, especially when trying to find, and hold, the exit pupil produced by eyepieces with long focal lengths and eye relief. Internal tube reflections had been very distracting before despite the baffles (yes, this thing has baffles), and are now just about gone. Other improvements will be more subtle than that, and I'll do a side by side later to see how subtle.

I then added a 28mm RKE and took it to an international dark sky reserve. Cracking views, with a well-corrected field (as you might expect at f/10), great contrast and a still pleasingly bright image for the 2.8mm exit pupil. Detail visible was a step up from the 7x50s I had also brought along. Power was 18x and enough to clearly show the triangular asterism in front of the Sculptor Galaxy, for example. Handheld, I might add. The long, light-weight tube is easy to hold steady with one hand resting against your forehead maintaining the correct distance between the eye and eye piece and the other holding the scope near the objective. A 10mm SV bony eyepiece (the best of the currently available series as far as I'm concerned) gave a power of 50x in this unit, which is enough to show the current crescent of Venus very well. The 2 main belts on Jupiter and ring of Saturn. All very small of course but pleasingly sharp. At that power, a photo tripod or lens beanbag should be used. So the first impression under truly dark skies is a nice setup for quick peeks at the major planets or low power sweeps of the Milky Way, all essentially for the cost of the 28 RKE and a tripod.

Last edited by N1; 10-10-2018 at 07:05 AM.
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  #2  
Old 09-10-2018, 06:08 PM
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ZeroID (Brent)
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Ha ! Great, always like to see minimal equipment being better than expected and fun to use. Some simple mods can be quite effective. Having two, do I see a possible binoscope build attempt coming up ?
I nearly picked up a part built pair of 80 f11's in binoscope configuration but funds were unexpectedly restricted at the time. Always wondered if I could make it operational.
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  #3  
Old 09-10-2018, 06:20 PM
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kinetic (Steve)
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I'd like to get hold of one of those too Mirko.
Here's a project I made a few years back, started as a non-working replica but then made it work with basic optics.
http://www.iceinspace.com.au/forum/s...d.php?t=112494



Steve
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Old 09-10-2018, 06:34 PM
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LewisM
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https://www.ebay.com.au/sch/i.html?_...scope&_sacat=0
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  #5  
Old 10-10-2018, 01:06 PM
N1 (Mirko)
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Brent, I was actually thinking along those lines but decided to keep one in its original state for now, and use the other to make some changes (such as the flocking) and see what they do, in direct comparison. The other reason was that I have a pair of CZJ 7x50s, although I'm starting to think that the image quality of the Galileoscope with a good eyepiece is actually better than that of the binocs, which are of fairly decent quality themselves. Can't compare them directly of course because the 1.25" drawtube of the G-scope means its power bottoms out at around 11 (with a 45mm EP) or 12 (as in my case with the 40mm TVPL), and with a certain AFOV penalty.

Steve, great effort on that Newtonian! Lewis' link has some good examples. I probably wouldn't pay more than $50-60 for a used one (mine were $20 each). I understand the last batch before production ceased was priced a bit less "budgety".

Would be nice to know who made the achromat objective - whose CA ratio (5) would be classed as pretty good by some.

Last edited by N1; 10-10-2018 at 01:20 PM.
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  #6  
Old 27-10-2018, 06:47 PM
N1 (Mirko)
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Flocking

Alright, so Venus was a no-show today (the current crescent is spectacular), but the thick, bright cloud cover today provided a good canvas for an exit pupil comparison between both scopes. Photos were taken a minute or so apart, same settings, same lens on the DSLR. They show the back end of the scopes, with a 40mm TVPL in place, giving an effective exit pupil of 4mm. They also illustrate what the exit pupil really is - an image of the objective (plus the inside of the OTA).

Flocked unit on the right. On the left, we see lots of light where it doesn't belong. The halo-like feature is light bouncing off the inside of the draw tube, so flocking that part alone would appear to get rid of most of the scattered light outside of the effective exit pupil, thanks to the baffles. Notice however the brighter central area as compared with the flocked unit. This may be due to light being reflected off the areas between the baffles and somehow affecting the light cone itself. Notice also the crappy flocking job, my first
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Last edited by N1; 27-10-2018 at 06:58 PM.
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