I have gone over to the Dark Side

For most of my observing “career,” I have starhopped to objects, later replacing a straight-through finderscope with an azimuth circle on the dob ground board, a digital angle gauge for altitude, an app for the alt-az coordinates of objects, and a right angle/correct image (RACI) finder to find things when my neck just couldn’t take the contortions of a straight-through finder anymore.

Well, that has been working fine, but I decided I needed a downsized scope for when I can’t handle the 10-inch dob. Enter the Sky-Watcher Virtuoso GTi 150 Tabletop Go-To Dobsonian.

Wait...what? Go-to?

Yep, I have gone to the Dark Side.

I did way too much research (although I had a lot of fun doing it), and finally settled on a 6-inch tabletop scope. This is my first new scope in 20 years. I’m an adherent to the philosophy that you really can’t beat aperture to see things better, so after much hemming and hawing I ruled out refractors, at least for now. A 6-inch refractor is huge, heavy, and very expensive. I also ruled out catadioptric scopes due to the total price per inch of aperture and the longer focal lengths with correspondingly narrower fields of view. I also don't want to see things mirror-reversed after looking at them for 30 years in correct orientation (albeit rotated 180 degrees).

I could have gotten a 6 or even 8-inch standard solid tube Dobsonian, but I kept thinking how nice it would be to have tracking, where the telescope’s motor tracks the object you are looking at so you don’t have to keep resetting the telescope as the Earth rotates. This is particularly nice during outreach events where you have a lot of people taking turns looking in the eyepiece. And I wanted to keep the weight and bulk down.

My choice for a downsized scope

I settled on the Sky-Watcher Virtuoso GTi 150P. I figured if I have to give up some aperture, I can at least add go-to and tracking to compensate a bit. This telescope is a member of the "tabletop Dobsonian” family, really a half-fork mount hybrid. Other telescopes of this type include the very popular OneSky from Astronomers Without Borders (see the megathread on Cloudy Nights), the Zhumell Z130, the Orion Starblast, and the Sky-Watcher Heritage, with models available in 114mm (4.5-inch), 130mm (5-inch) and 150mm (6-inch). When in doubt, my advice is to take the larger aperture when possible. The Virtuoso GTi is the only one with a go-to mount at this time.

This particular scope has a roughly 14-inch diameter base, a 16-inch tube when collapsed (27 inches when extended), and weighs a total of 19 lbs., which is 49 lbs. lighter than my 10-inch and a whole lot more compact. Now that's downsizing!

I’ve had the scope out in the Redneck Observatory a few times and to my regular semi-dark site a couple of times. It’s taking a bit of effort to get used to the go-to, which doesn’t always seem to play well with my Android phone, but when it does, it’s pretty cool. I do love the tracking. The phone disconnects every 15 minutes from the scope’s WiFi unless the Synscan app is in the foreground, and I’ve tried every tip from users to no avail. Eh, not a biggie, but still annoying.

After trying to control the scope through Sky Safari Pro with its “tilt to slew” feature and constantly overshooting the target, I decided to just use the Synscan app to center objects after the initial go-to movement done through Sky Safari Pro. I dial the slew speed down to 3 in Synscan and it works pretty well. I have had it sometimes just start slewing off the object on its own, but I'm not sure that isn't user error. I still say it’s a whole lot easier and a lot less frustrating just to push a non-go-to dob around manually to find stuff.

The scope retails for $470 currently when not on sale, which is a pretty good price for a 6-inch mirror, go-to, and tracking. It will even resume tracking if you disengage the motor to manually move it around and then reengage, what they call "Freedom Find," using dual encoders. More important, the optics are good. Most important, it's fun!

As with any inexpensive telescope, there are suggested mods. Of course you’ll need a table to put it on, one that is stable. I built an 18-inch round table out of a scrap of 1/2-inch plywood and three legs from 2x2s screwed into t-nuts so I can break it down flat. A popular solution is the Super Simple 2x4 Tripod for Tabletop Telescopes if you want to stand and observe. If you don't want to build your own, some people recommend this stool or this table from Ikea.

The helical focuser also has some play in it, which has several potential solutions. The one I implemented was putting a 2-inch hose clamp around the top of the focuser housing and tightening just enough to take out the play. I also smeared some lip balm on the threads. I really like it now. I find I can use my Svbony 7-21mm zoom eyepiece no problem without any twisting and shouting. My Baader Hyperion zoom sits all the way down in the focuser to the point where the thumbscrews holding it in rub against the bottom edge of the eyepiece housing, but it works, and it's a better eyepiece than the Svbony (also a lot more expensive). [Edit: I added an O-ring to the barrel of the Hyperion and it no longer scrapes.] I also constructed a light shroud out of black craft foam, because with the upper assembly extended on two truss tubes there is no protection from light and dew, both common in my neck of the woods.

Added a light shroud and 11" high tripod table.

The main problem for me, aside from these quirks, is the red dot finder, which is a very cheap plastic thing mounted very close to the tube circumference. My neck just can’t take straight through finders anymore, but fortunately you only need it for initial alignment, although I have found I sometimes need to align it a couple of times during the night when it decides to go off somewhere on its own instead of where I tell it to go.

To solve the finder issue, I zip-tied a dovetail base for my right angle correct image Svbony SV182 finder that normally lives on my Tasco 4.5-inch to the end of the green dovetail bar. Not optimal placement, but about the only place it can go on this design, and it works without messing up the balance. I just need to get up out of my seat to look through it. In regular star hopping use this would be unacceptable, but for alignment it works okay. I might make a more permanent mounting piece out of wood. There is a 1/4-20 tapped hole there so I wouldn't even need to drill any holes in the tube.

RACI finder mounted on the end of the dovetail
(green) with a zip tie.

I opted for a reflector over a "cat." Kitty was not 
amused, but seems over it.

I’ll post updates as I get more used to this thing of the Dark Side. In the meantime, I have made a mod to my 10-inch manual dob so I can keep using that, too, despite my deteriorating physical condition.

7/19/24 update: If you have an Aldi store nearby, the Easy Home Collapsible Hamper makes a great cover for this scope. Turn it upside down and it's the perfect height. Also keeps its shape.

8/31/24 update: See my post Why does finding things easily have to be so hard? for my issues with the go-to and tracking on this scope.