Let's Catch Up: The Orion ShortTube 80-A

 I got a new telescope. Oh golly!

The Orion ShortTube 80-A. I ordered it just after Christmas, and was expecting it by the end of January. I ended up getting it on the 5th of January. Excellent.

But why? I just got a 10" Dobsonian, after all! Why step down in size? Well, as I've mentioned before, I like to observe with small telescopes and wide, rich fields of view. The Celestron FirstScope was the only telescope I had to fill that niche, but it has one small problem: it is really not very good. And that's okay, I got it for one dollar and it sells new for $50 ($60 or $70 if you want the good eyepieces and a finder). But I wanted a grab-n-go portable telescope which wasn't so... aberrant. The ST80 was the answer.

I wanted the ST80 for the following two reasons:

• Portable telescope for when I don't want to bring out one of the big dobs.
• Rich, wide field of view which is unattainable with any other telescope I own.
  

I knew I'd wanted an ST80 for a while now. But which one to choose? Ever since Orion first sold the Synta 80mm f/5 achromat as the Short Tube 80, there have been clones from other sellers. (typically made in the same factories and more or less identical aside from livery and accessories). There's a lot of variations on the ST80. There's the SkyWatcher StarTravel 80 on an altaz mount, the Meade AdventureScope 80, the Celestron TravelScope 80, and Orion sells an OTA only, a terrestrial spotter, an an astro-scope, as well as the Compact-Tube 80 on an EQ mount sneakily named the 80ST.

The AdventureScope 80 and Celestron TravelScope 80 all sell for about $100, which is the cheapest way to get it, even cheaper than Orion's OTA-only version. However, the accessories and mount are so bad that it may as well be an OTA only. Both have the same optics and same awful tripod, but the Meade's accessories are marginally better (a 90-degree erect-image diagonal instead of a 45-degree one, and a red dot finder instead of the worst optical finder ever), and the Celestron has a plastic focuser instead of metal. But they both have no tube rings and only a small vixen dovetail. And I wanted to use them on an EQ mount (which may have been a stupid idea, to be honest), so that meant buying tube rings and a longer dovetail anyway. 

The Orion 80ST Equatorial Refractor Telescope was a really cheap unit overall and had most of what I wanted, and I almost went for it, except that it is NOT an ST80. It's a CT80, with a cheap plastic focuser and lower overall quality. It (and the CT80) are a holdover from when the ST80 was temporarily discontinued by Orion in 2016. Orion now sells a real ST80 on an EQ-1 mount, but that came out mid-January.

I ended up going for the Orion ST80-A, and that's probably what I would recommend to most people. You will still need a separate mount for it. The ST80-A is the most expensive iteration of the ST80, but adding up the price of all of the accessories it comes with--a vixen plate, the tube rings, a star diagonal, two eyepieces, and an 8x40 finderscope--it is by far a better deal than sourcing these things separately.

I also bought the Explore Scientific Exos Nano EQ3 mount. This wasn't the right choice for reasons I'll get into later, but it is definitely preferable to using it on a photo tripod.

Ed Ting claimed the ST80-A is able to be used on a photo tripod, and it just... barely works. It was pretty awful to use, even though my photo tripod is pretty good and sturdy. Balance is just impossible, so movements in altitude are always extremely jerky and it was just no fun at all. My ST80 arrived on the 5th, a night of poor weather, and combining the poor weather and poor mount I didn't get a good first impression with the ST80. Luckily I knew it wasn't the scope's fault, and I wasn't too disappointed.

To my surprise, the Nano EQ3 mount arrived the very next day (I didn't even have an ETA on that purchase, I figured it could be months!), and so I was able to try it out with a nice smooth proper mount.

 

The EQ3 mount has a few big drawbacks which means that it doesn't really suit the ST80. The ergonomics aren't great, due to it being an equatorial mount. It seemed like I could never get the eyepiece at a comfortable position whilst sitting, and the finderscope would never be usable while standing. Equatorial mounts are also somewhat confusing to use, and while they are easier to use at the zenith, that doesn't mean the eyepiece height will cooperate at the zenith. But probably the biggest problem for this application in particular is that it's not a great grab-n-go mount. It's buttery-smooth when moving and tracking, as it should be, but it's significantly heavier than it needs to be, and it doesn't go out with one hand like the photo tripod does.

The ergonomic problems turned out to be exacerbated by being out in the back yard on very soft grass. My chair sunk into the dirt, and so I wouldn't be able to scoot around--when I tried it again on concrete, the ability to easily scoot around made a huge difference for ergonomics, since I can easily vary the neck-eyepiece distance.

One of the ergonomic problems with the scope was the straight-thru 8x40 finderscope. The finderscope is a weird choice for this telescope--it's huge! At 40mm, it has 1/4th the light grasp of the ST80, and at 8x it has most of the magnification of the minimum power of the ST80. The view through the 8x40 vs the ST80 + 32mm Plossl wasn't that different. More pressingly, the eyepiece of the finder is a little too far backwards. This means getting your head under the eyepiece when it's pointed high can be a struggle, and so for many orientations you're too uncomfortable to take advantage of the finderscope as a navigational aid, merely as a pointer. I tried swapping it out for the 8x50 Right Angle finder from my 10" Dobsonian, but I really do like to have a straight-thru pointer as well for finding stuff.

I solved the finder problem by ditching the 8x40 finderscope and buying a cheap used Red Dot Finder with a compatible synta finder dovetail plate. I find the RDF to be much more usable than the straight-thru finderscope, and it really, honestly, well and truly is accurate to say that at a minimum power of 12.5x, the telescope is its own finder. 

Despite the ergonomics problems, I was able to do some good observing on that first EQ-mounted night. Messier 31 was beautiful, M33 was easy, and remarkably enough I could even see M110! M110 eluded me for years until I found it for the first time in autumn with my 6" Dobsonian in dark suburban skies. I can usually see it in mid-bright suburban skies with my 10" Dob. 

It does a very good job with the Double Cluster. Despite its purpose for exploring rich fields, I do often bring it up to mid-power (about 27x, maybe 40x). It does many open clusters very well at a range of powers. At low powers, the winter open clusters M35-M38 are glittery blobs, but resolve very well at higher powers.

I was even able to find the Blue Snowball planetary nebula, which was cool to see. It was a colorless gray dot with the faintest hint of hollowness, like the Ring Nebula at low power in the 50mm Galileoscope. Star hopping with equatorial slow motion controls is a pretty cool thing--you can sort of sail like they did before marine clocks, finding something at the right declination and slewing to the correct right ascension, as ships sailed to the right latitude before sailing east or west with no ability to precisely determine longitude.

Some say that the ST80 can perform very well at high powers if you can control chromatic aberration with filters. That may be, but 

I did a star test before making any modifications to the telescope. It suffered from miscollimation/coma, some kind of misshapen pinched optics, and I believe there's an unfortunately large degree of spherical aberration as well. It's unclear how much of this is due to the star diagonal, but I don't have a straight-thru adapter to try to do a star test without the diagonal. I fixed the pinched optics by loosening the lens cell enough for it to rattle very slightly if shaken. But I haven't tested it since.

One day I will write a full review of the ST80, but overall I am fairly pleased with it, and I just wish I had chosen a better mount--an altaz mount would be ideal--so it can truly be a grab-n-go scope.

I will also one day write a full review of the Explore Scientific Exos Nano EQ3 mount, but I'd like to try it with some more telescopes first.