Tube Rings for the Orion SkyScanner

For Christmas, I bought my cousin Quinn (19) an Orion SkyScanner 100, one of the telescopes I recommend most for beginners on a budget, especially but not limited to kids. As noted in my review and pretty much any time I talk about it, the position of the red dot finder and the eyepiece is... frustrating, to say the least. The eyepiece ends up too high and the straight-thru finder too low. While teaching Quinn, how to use the telescope, we found that due to some motor disabilities she deals with, the telescope was ergonomically almost unusable. So I had to work to fix the eyepiece and finderscope problem.

The Orion SkyScanner 100 is a 4" f/4 Newtonian reflector with a non-diffraction-limited parabolic mirror, on a tabletop Dobsonian mount which is simple, sturdy, and easy to use. As the name implies it's to be used for scanning the skies for deep sky objects, a bit like a pair of binoculars, except with a sturdy mount instead of a finicky tripod or wobbly hands. This use case requires being very comfortable to use and having an adequate unit-power finder, since a right angle finderscope would be overkill.

The SkyScanner's eyepiece is on the top of the OTA (when pointed near the horizon), and thus you have to lean down over it to look through. The red dot finder meanwhile is on the side, meaning you have to bend down very low to get your eye behind it. I can barely do it, and don't have great mobility myself. Quinn has worse mobility than I, and simply can't get her head behind the finder in most cases.

In an article by Matt Wedel on his blog, 10 Minute Astronomy, he details 6 hacks to the Orion SkyScanner including remounting the dovetail bracket to a different angle, thereby putting the eyepiece at a more comfortable angle. He doesn't like red dot finders (I like them fine, when used properly) and removed his, but the replacement laser wasn't an option in this case. With Quinn's permission, I was going to keep the SkyScanner for a few days and drill out the new holes to remount the dovetail, but I chickened out since I have no experience with drilling holes in metal and it wasn't my telescope to ruin.

Instead, I decided to order some tube rings from Orion. The 116mm tube rings I ordered, based on measurements of the tube's outer diameter, turned out to be slightly too large. I suspect 115mm is perfect. I didn't order a dovetail bar, to save money, since the telescope already has one.

I've been very lucky with pandemic telescope availability, and most of the equipment I've ordered has arrived ahead of schedule. However, when I ordered the tube rings something like the 22nd of December for an expected delivery date of mid-January, they didn't arrive until the 16th of February.

In the meantime, we discovered that with the SkyScanner with its base mounted on one of my tripods, the eyepiece position was a little worse but the finder position was partially solved. With that temporary solution, we waited. The telescope still didn't see much use. When the tube rings shipped, she left the telescope at my house again. When they finally arrived, I started my surgery.

The trouble is that the SkyScanner's permanently-mounted dovetail uses a nonstandard screw compared to what tube rings are expecting. Small screws and a small nut hold the dovetail into the metal OTA. In fact they seem to be #8-32 screws. I went to a hardware store and found the right screws, and found longer ones. Using the washers from the tube rings, with new nuts and a 1 inch long screw, I was able to sort of hack together a solution, using the original SkyScanner dovetail with the new rings.

Finally it was put together. I tried it the next night and was a little disappointed. The dovetail wasn't tightened well enough and it wobbled a lot as I tried to move the scope. This was easily fixed. But though the finderscope could be rotated to the top of the tube, the eyepiece had to be on the same side of the mount as the altitude fork-arm. And since the tube rings added perhaps a half-inch extra distance, the eyepiece was farther inwards, meaning it was very difficult to reach the eyepiece without being forced to brush up against the mount, causing wobble and vibrations at the eyepiece and just general discomfort.

I had to figure out a way to put the red dot finder on the other side of the focuser, so the focuser could be rotated away from the altitude arm without the red dot finder going on the bottom. I ordered some foam tape. Hey, if it works for telrads...

When the tape arrived, I tried to fix the finder to the telescope tube. It was kind of bouncy and it didn't feel sturdy, but I supposed it'd have to do. I put it back on the tube rings. And... it was... the wrong way around.

I facepalmed. There was good news and bad news. The bad news was I'm a moron and bad at spatial reasoning. The good news is there was no need for the soft wobbly foam tape. You can just mount the optical tube backwards. Which I had done by mistake when remounting the scope in the rings. I wasn't able to think of this before since without rings there's no way to just, turn the scope upside down without the finder being stuck in a bad position. But with rings you have the freedom to do whatever you want with the finder position.

So now we have the telescope in its final (at least for now) state. With the red dot finder able to be rotated to the top, the eyepiece rotated to the side. It still isn't ideal when sitting at a table, but it's a lot better. A shorter chair or a taller table would help immensely, you need to have a pretty small distance between the base of the SkyScanner and your neck. If the base of the scope is below your chest (as if you're sitting at a table) you're gonna have a bad time.

So I ended up letting Quinn keep the tripod, at least for now, until I can find a better solution. As it is it works reasonably well. It can be raised up to allow for aiming near the zenith, which is still difficult, but it's much more usable now and I expect it will get a lot more use.

Post Script

I'm not the only one to think of putting tube rings on a tabletop dob. Of course the Orion StarBlast 4.5 and 6 both have tube rings, and I've seen people put tube rings on the AWB OneSky 130/SkyWatcher Heritage 130P.

Most notably, CloudyNights user SkyMuse has done a fine job at hacking together the SkyScanner 100's twin, the Zhumell Z100. The Z100 has pretty much the correct finder and eyepiece position from the get-go and so it gets my recommendation over the SkyScanner, as long as you find them for the same price. SkyMuse's threads are really interesting, the way he turns toy telescopes into something much more is quite the spectacle. And yes, they too have used tube rings. SkyMuse's Z100 Thread.

He also has one on the dreaded 127EQ Bird-Jones (one of the worst beginner telescopes of all time), which he calls "The Bird."

I should have gone with the Z100 in the first place. Hell, maybe I should have gone with that very nice 100mm short-tube refractor I sold all along. I still regret selling that. If I had been able to make that review while I still had the telescope, I'd have been able to afford to keep it instead of having to sell it to get the SkyScanner for Quinn. Some people might think me insane to sell a nice 100mm short tube achromat for a toy like the SkyScanner. Maybe that's true. But it wasn't for me, it was a gift for a beginner with mobility problems in her hands, and I just didn't think the AZ3 mount would work well for a beginner due to the limited travel on the slow motions and how the clutches work.

Finally, the EQUATORIAL TABLEDOB STRIKES BACK, now that it has tube rings:

 Just a little experiment. ;)