Sky-Watcher’s 8” Traditional is one of my favorite 8” Dobsonians that I recommend to those on a budget. Why, you may ask?
It’s simple, offers the lowest price of all of the commercially available 8ʺ Dobsonians, and gives you great bang for your buck. Let’s get into what makes this scope so great, as well as a few criticisms.
The Optical Tube In 8" Traditional
The 8ʺ Traditional is an f/5.9 Newtonian, manufactured by Suzhou Synta Optical Technologies (Synta), the same company that owns Celestron. Synta also builds Orion’s XT and XX Dobsonians. The mirrors are made of borosilicate glass, also known as Pyrex, which expands far less with expansion and contraction than plate glass.
This means your telescope doesn’t need to acclimate to cooler temperatures, as long as the telescope has a glass-plate.
At a focal ratio of f/5.9, there isn’t any coma like faster scopes have, such as the Sky-Watcher’s 10ʺ and larger models. The optical quality is usually quite good.
The 8ʺ Traditional’s tube is identical in length to the Sky-Watcher’s tube, as well as other manufacturers’ 6ʺ f/8 Dobsonians. As a result, the 8ʺ Traditional is not really any more cumbersome to transport or difficult to store than the 6ʺ Traditional.
The focuser on the 8ʺ Traditional is a rack-and-pinion, which uses a toothed gear on a rack to slide the drawtube inwards and outward. The rack-and-pinion design works pretty well, but I don’t love the plastic knobs on it, which have a tendency to dig into your fingers.
Additionally, the extension tube/adapter system is a little convoluted. You either have to use the 1.25ʺ or 2ʺ extension tubes that Sky-Watcher gives you.
Otherwise you can leave the 2” extension tube with a 1.25ʺ or 2ʺ adapter.
The 8ʺ Traditional comes with 25 mm (48x) and 10 mm (120x) Plossl eyepieces, made of plastic. They work well, but you’ll want some additional 6 and 9 mm gold-line eyepieces (at the minimum) for high magnification.
You’ll also probably want a 2ʺ wide-eyepiece to get the maximum possible field of view at low power. With this you would have a large view of nebulae, star clusters, and other deep-sky objects.
The 8ʺ Traditional comes with a 9×50 mm straight-through finderscope. In addition to being uncomfortable to sight with, the finder’s images are inverted. However, it works just fine.
A Telrad is far easier to use, and a 50 mm right-angle finder will also work well and do wonders for your neck.
The Dobsonian Mount
Like all other Chinese-made Dobsonians, the 8ʺ Traditional’s mount is made of melamine-covered particle board. This is basically sawdust compressed with glue, like a cheaper version of the stuff your IKEA furniture is made out of.
It’s heavy compared to plywood, and if the melamine is damaged even slightly from moisture (from, for example, using the 8ʺ Traditional in grass), the melamine will warp.
Unlike Orion’s XT Dobsonians, which use springs for altitude tensioning, and have the altitude bearings sit in cutouts in the mount, the Sky-Watcher Traditional Dobsonians have the altitude bearings sit on brackets inside the rocker sides. This makes replacing it with a plywood rocker more complicated if you aren’t an experienced woodworker.
Altitude tensioning is provided by the two handles that stick out from the rocker (basically bicycle grips). They work well, but the handles can get caught on things such as loose clothing, especially in the dark.
The scope’s motions are pretty smooth, but the azimuth motion can be improved by replacing the cheap nylon pads with real teflon pads (available from various vendors on eBay and some hardware stores) and nailing a sheet of formica onto the azimuth board.
Due to the design of the altitude bearings, I would not recommend tampering with them.
The mount comes with a handle and an eyepiece tray, which is a nice convenience. However, I don’t recommend using it. It would likely be a good way to get your eyepieces damaged, dewed up, or dirty.
In The Field
I really like solid tubes for 8ʺ Dobs or larger. A 10ʺ scope becomes a bit uncomfortable to wrap your arms around, and a 12ʺ or larger is a nightmare to handle, unless you are built like Paul Bunyan.
The moon looks good in any scope, but an 8ʺ is a good general size for lunar viewing. With an an 8ʺ telescope, you’ll have decent resolution, but the moon won’t be blindingly bright at lower magnifications. Clavius, a crater on the moon, can show three or four dozen craterlets, provided there is good seeing and collimation.
Jupiter’s moons will look like sharp and ruddy-orange, yellow disks with an 8ʺ scope. Jupiter itself shows many cloud belts, and of course the Great Red Spot.
Saturn shows several cloud bands – currently it has three major ones – as well as the Cassini Division in its rings, and several moons. Saturn’s largest moon, Titan, will appear to be gold, as opposed to the more monochrome look it has as a smaller instrument.
Uranus’ moons can hypothetically be glimpsed with an 8ʺ scope, but I’ve never done it. Neptune is a sharp, azure disk through the scope, and Triton can be seen as well.
Outside the solar system, the 8ʺ aperture is enough to show you the entire Messier catalog, though a few galaxies like M74 and M83 may be difficult to see if your location suffers from light pollution.
The famous Whirlpool Galaxy can show a hint of spiral arms from a dark site, and its companion, the M51B/NGC 5195 galaxy is easy to see as well. M81 and M82 in Ursa Major are both quite interesting to view as well.
The Virgo Cluster becomes a bit crowded with other galaxies during the spring. During autumn, several smaller galaxy clusters may show at least one or two bright members with effort.
There is a good resolution for globular star clusters with the 8ʺ. The M2, M3, M5, M13, M15, and M92 star clusters in particular tend to show a fair amount of stars sprinkled across your view.
The M4 may yield a fantastic view if you don’t live too far north, and if you don’t have much light pollution to your south. Even the dimmer Messier globulars like M10, M12, and M79 can be seen with practice.
Many planetary nebulae, besides the Ring and Dumbbell, are interesting to investigate with an 8ʺ, particularly with a light pollution or oxygen-III filter. Examples are the NGC 1535 in Eridanus, the Eskimo Nebula in Gemini during winter, and the Blinking Planetary nebula and NGC 7027 in Cygnus during summer.
While there are one or two 8ʺ Dobsonians with extra accoutrements that I might recommend over the Sky-Watcher 8ʺ Traditional, none deliver the same value.
If you’re on a budget, and would rather save spending money on accessories for later, the Sky-Watcher 8ʺ Traditional is your friend.