by by Ben Lawry
DSLR astrophotographers must strike a delicate balance between ISO sensitivity, aperture, focal length, and exposure time every time they take a shot. The greatest single factor influencing all of these variables is the rotation of the earth. The iOptron SkyTracker attempts to relax these variables by cancelling out Earth’s rotation. Is it worth the price?
The SkyTracker (v2) is a tripod-mounted accessory that allows a DSLR to track stars as the earth rotates about its axis. The rectangular body of the SkyTracker can be tilted from 0 to 70 degrees, allowing pretty much anyone not living near the equator to polar align it. The front side features a circular mounting plate with a 3/8″ bolt that allows most larger ball heads to be attached. The large hole in the corner is precision-machined for the insertion of a polar scope (included).
On the back side are several switches (on/off switch, Northern/Southern mode switch, and 1X or 0.5X sidereal tracking rate mode switch), as well as a battery cover plate. You can either run the SkyTracker using 4xAA batteries or a 9-12v DC adapter (sold separately). All in all, it’s a fairly simple design. One nice feature unique to the “v2” version of the SkyTracker is a locking azimuth adjustment wheel. The original SkyTracker does not come with this adjustment wheel, but is otherwise the same.
Made mostly of metal, the SkyTracker feels solid, coming in at 2.6 lbs without batteries. The components are reasonably high-quality. The polar scope is all metal on the outside. The glass provides a clear view of your polar alignment stars and includes etched alignment guides that glow red when the SkyTracker is turned on.
There’s very little play in the polar scope when attached and locked, and the camera mounting point is solid too, when properly tightened. The azimuth adjustment ring (in versions that include it) locks down solidly as well. The elevation adjustment is a little loose all on its own, but comes with a silver clamp that can be used to eliminate play here too. All in all, it’s a pretty solid piece of equipment if you remember to lock everything down.
Where the SkyTracker loses a couple stars is in the battery compartment and power switch. The battery box is made mostly of rigid plastic and the wires connecting it to the electronics inside are very short, which makes swapping batteries difficult. Another minor annoyance here is that the battery box can almost be re-inserted rotated 90 degrees from the way it was intended to be inserted. If you forget which way it’s supposed to go, there’s a good chance you’ll try to do it wrong at least once in the field. The only indication you have that you did it wrong is that the back cover will fit back on, but VERY tightly. I ended up breaking off one of its two teeth this way. Lesson learned.
The power switch is solid, but it can be turned on inadvertently even when the SkyTracker is packed away in its plush carrying case. On two occasions, I’ve arrived at a site only to find that the batteries had been completely drained before I got there because of this issue. You can avoid this by removing the batteries after each use, but because of the aforementioned battery box issues, it is kind of a pain
Despite my gripes about the power switch and battery box, the SkyTracker is still reasonably well-built. I really like the mostly-metal construction, and the whole thing feels reasonably solid.
Build quality verdict: 3 out of 5 stars.
The whole premise of the SkyTracker is pretty simple: keep the stars in the sky from trailing in your pictures. To do this well, you really only need to be able to polar align it and then track at at the sidereal rate.
Minimally, you could run this all on batteries and get away with a good illuminated polar scope and a solid elevation adjustment knob. The SkyTracker comes with a few extra bells and whistles beyond this minimal set of features that really come in handy:
AC/DC adapter compatibility
0.5x tracking rate mode (great for shooting nightscapes)
Azimuth adjustment wheel (v2-only)
Aside from the azimuth adjustment wheel, my favorite added feature is the 0.5x sidereal tracking rate option. For nightscapes with a lot of foreground detail, this option lets you expose the sky twice as long while still having an acceptable amount of star trailing. Shooting this way does impart trailing into your foreground, but if you’re careful, doubling your exposure time can really make your nightscapes pop.
The single biggest reason why I can’t give the SkyTracker’s feature list a five-star rating is because it lacks a level bubble. Unless you’re pushing the limits of the SkyTracker with a 200mm long lens, most of the time you can get away with just eyeballing it, but it still feels a little kludgey to work hard at getting good polar alignment without knowing whether the whole setup is really level or not. This won’t matter if your tripod comes with a level bubble, but neither of my moderately-expensive Manfrotto tripods came with one, and I’d just as soon sacrifice the built-in compass for a level bubble if I could.
Another feature common to telescope mounts not present in the SkyTracker is an autoguider port. Autoguiding is essential to long focal-length tracked imaging. The lack of such a port doesn’t affect the final score here because it’s frankly not something you’d ever need when imaging at the short focal lengths the SkyTracker was designed to be used with.
Features score: 4 out of 5 stars.
The SkyTracker is about as heavy and just a little larger than most of the lenses I bring to the kinds of shoots I use it on (100-135mm maximum focal length), so it doesn’t represent much of an increase in effort to bring it along.
Setup is fairly simple. You just put the SkyTracker on top of your tripod and then your ball-head or pan-head on top of the SkyTracker. After you’ve attached your camera body and lens, the polar alignment process is pretty simple. I use the free PolarFinder app from the Google Play Store, which has an iOptron-style reticle display that makes alignment very simple. A similar iOS app called Polar Scope Align is also available for free on the App Store.
Things that could be improved are the polar scope design and overall size of the main body of the SkyTracker. For some southern-facing targets (if you’re in the northern hemisphere), you will only have so long before the camera lens runs into the SkyTracker body. The polar scope can also get in the way of the camera, so it’s best to remove it before you start your imaging sessions. A final issue is that, if your pan-head or ball-head friction is set too high, it’s pretty easy to knock the SkyTracker out of polar alignment. For these reasons, I can’t give the SkyTracker a five-star rating.
Ease of Use score: 4 out of 5 stars.
Brand new (at the time of this writing), the SkyTracker goes for about $300. Oddly enough, the updated SkyTracker Pro,
which is better-designed, more compact, lighter, and comes with far more features, goes for $290. If you’re going to buy brand new, the Pro version is hands-down the better option.
However, used SkyTrackers can be found for $150, sometimes less. If you’re on a tight budget, knocking half the price off is definitely worth it, in my opinion.
Value score: 3 out of 5 stars, if buying used.
The iOptron SkyTracker was one of the first compact, affordable tripod-mounted trackers available to DSLR astrophotographers and continues to turn out good tracked images of the night sky. It probably isn’t the right choice for someone who has already invested in a tracking setup (look to the “SkyTracker Pro” or “SkyGuider” models if this applies to you), but if purchased used for the right price, the SkyTracker can still provide an excellent introduction to tracked astrophotography. If you’re still not convinced one way or another, take a look through the example images I’ve made with the SkyTracker below and decide for yourself!
Final score: 3.5 out of 5 stars.