Star Tracking
I have always been fascinated by the night sky. As far back as I can remember I have been interested in the stars, from TV programmes like Carl Sagan’s Cosmos and more recently Brian Cox’s Wonders of the Universe. As a young child I regularly wrote to NASA for photographs, press releases and other information.
From this website you will see my passion for photography, so I decided it was about time I combined my love of astronomy with my photography and try my hand at astrophotography. I had previously owned large telescopes but found the process of setting up, aligning and finding objects in the sky to be quite frustrating. Mounts were bulky and heavy, and given my location on the edge of an urban area, it wasn’t practical to transport them to dark sky locations. After a number of failed attempts at taking photographs through these telescope I decided the best thing I could do was to give up!
More recently, however, I found the Nightscape Images YouTube channel, where Australian photographer Richard Tatti was taking some truly amazing images combining landscapes with the Milky Way using standard DSLR cameras and photographic lenses. As I already had a range of mirrorless cameras and suitable lenses I thought I would give it another try.
With a little research I found that if I wanted to get clean images of the stars at low ISO values I would need long exposures, but this would result in the stars becoming elongated and trailing. In astrophotography there is a guideline, the Rule of 500, which basically states that to get round stars your maximum exposure should be 500 divided by the focal length of your lens. (The equivalent Rule of 300 should be used for crop sensor cameras). With a high resolution camera it is preferable to use about 2/3rds of the exposure calculated so, for a 45MP full frame camera like my Nikon Z7ii and my Nikkor Z 14-24 f2.8 S lens I would be looking at a maximum exposure ranging between 15s and 25s.
Looking at exposure data it appeared that I would need an ISO of 3200 - 6400 if I wanted to use my f2.8 lens and maintain a shutter speed faster than 25s. If I wanted longer exposures to get cleaner images I would need some way of mounting the camera on a powered tracking mount.
After a little more internet research I decided it was time to get a star tracker.
What does a Star Tracker do?
It probably doesn’t need saying but the stars in the night sky are actually not moving - it is the rotation of the earth that makes the stars appear to move relative to the observer. (I know that technically the starts are moving as the universe expands, etc. but that’s a different matter). The star tracker is basically a camera mount that has a small motor drive that compensates for the rotation of the earth by itself rotating on the same axis as the earth but in the opposite direction. To the camera, the stars appear to be stationary giving the ability to photograph night sky objects without star trailing, breaking the Rule of 500 and allowing much longer shutter speeds.
There are a range of different trackers available at a range of prices, primarily dependent upon the accuracy you need and the weight of the photographic equipment you need to support. Moving to mirrorless has helped here as the cameras and lenses tend to be lighter than their DSLR counterparts. At the more reasonably priced end of the market there are trackers from companies such as Move Shoot Move, iOptron and Sky Watcher. Even Benro has produced a computerised mount that is capable of tracking the skies, but at north of £1200 this is hardly budget friendly!
After weeks of to-ing and fro-ing I decided on the Sky Watcher Adventurer 2i.
The Star Adventurer 2i comes in a number of different packages, the Star Adventurer 2i itself, the Astro Package (with declination bracket and counterweight), the Photo Package (with ball head mounting plate) and the Pro Package (with everything). Contrary to what you might think the Pro package is more suited to astrophotography than the dedicated Photo package, especially if you want to try deep sky objects (DSO) like nebulae or galaxies.
Sky Watcher Star Adventurer 2i Pro Pack
What’s in the box?
Star Adventurer Mount Head with built in polar scope
Equatorial wedge
Ball head adaptor
Illuminator for polar scope (with CR2032 battery)
1kg counterweight
Counterweight shaft
Adjustable Declination Bracket with Declination Fine Adjustment
Build Quality
The main body of the Star Adventurer 2i is metal, it is solid and seems to be good quality. Parts like the mode dial, clutch, battery cover and polar scope cover are all plastic but feel reasonable. The integrated polar scope is also metal (and glass). Reviews on the internet suggest that the battery cover and polar scope cover have a tendency to keep falling off as the plastic retaining clips wear. Time will tell.
Sky Watcher has updated its colour scheme from the red and black of the original Star Adventurer. The 2i features a more stylish and modern white and black colour scheme with green accents.
The equatorial wedge and fine tune mounting bracket are made of metal with knobs and adjusters made of solid or rubberised plastic. The actual saddle (clamp) on my wedge wasn’t particularly tightly fitted onto the wedge. I didn’t notice this at the time of first assembly but it was loose enough to make polar alignment and tracking seem very poor. Sky Watcher includes an Allen wrench to allow you to tighten these bolts though. The wedge also includes a bubble level to assist with levelling the mount.
When you first get the Star Adventurer you need to mount the small metal vixen dovetail bracket to the base of the unit (hex bolt and thumbscrew to prevent the unit twisting on the bracket). This is stored in the wedge saddle clamp (see below) during shipping.
The polar scope illuminator is made mainly of plastic and feels like an afterthought. It does its job though, although it is likely to be lost quite easily. There is no on/off switch for the illuminator - just an intensity dial. To turn off the illuminator you are supposed to unscrew the battery compartment door until the battery breaks contact. In my case the cover fell off without this loss of contact so it’s not a very reliable approach. Looking on internet forums though it appears that turning the illuminator dial fully down maintains the battery quite well.
All in all the Star Adventurer 2i is very good quality, solid and well built. It is a quality product however there are some areas that could have been improved further.
Functions
Below you can see the mode dial on the side of the Star Adventurer 2i main unit, rotating it allows you to choose the mode you wish to use from the following options:
I have yet to try the time lapse modes of the Star Adventurer 2i so will provide a future post once I have figured out how to use these settings.
With the dial set to APP, the Star Adventurer 2i switches on it’s WiFi hotspot allowing you to connect a smartphone and control the settings using the free Sky Watcher Star Adventurer Mini Console App.
On the opposite side of the Star Adventurer 2i there is an N, STOP and S slide switch. Select N for celestial object tracking if you are in the Northern Hemisphere, S in the Southern Hemisphere (you can see I have it set to N as I’m in the UK) and the middle position, STOP, to set the Star Adventurer to stop tracking.
Above the slide switch there are two direction buttons you can use to slew the Star Adventurer 2i to help align the camera lens. Slewing is only available for the RA axis since the DEC axis isn’t motorised. The slewing speed issue quite low though so I undo the clutch on the front and manually position my camera to point at the object I want to photograph and then re-lock the clutch. I then use these direction buttons for fine tuning the composition as it is easy to overshoot if you use the clutch mechanism with long lenses or telescopes.
Below the slide switch there is a SNAP port for connecting your camera to the Star Adventurer 2i so that the mount can trigger your camera’s shutter. This requires a dedicated cable, depending on your camera make and model, and is not provided in the kit. Setting the camera shutter time, delays, intervals etc can be done via the app. I don’t use this myself as I like to use a dedicated intervalometer attached to my camera.
There is also an Auto guider port/connection for attaching an auto guider, and a mini USB port for upgrading firmware and also powering the unit from an external battery pack. The Star Adventurer 2i uses 4xAA batteries for power which are claimed to last for several days of constant use.
Setting Up the Star Adventurer 2i for the first time
You would have noticed the Star Adventurer kit does not come with a tripod, this is because you can mount it to any tripod that uses a ¼” or 3/8” screw attachments (mosst photographic tripods), I use mine mounted to my Induro Grand Stealth 404XL.
I won’t go into too much detail of the setup procedure as there are numerous YouTube videos showing the basic setup but I generally do the following:
Firstly determine the latitude of the area you are located at. Most smartphones will provide latitude and longitude coordinates of your current position, or you can use paper maps or Google Maps to determine the latitude you are at.
Use the altitude adjustment knob on the wedge to dial in the approximate latitude and tighten down the adjustment lever.
Once the altitude is adjusted correctly mount the wedge onto the tripod.
EQ Wedge set up for latitude of 54 degrees N and mounted on the tripod
Using a compass or smartphone arrange the tripod so that the altitude adjustment knob on the wedge is pointing North (in the northern hemisphere).
Once aligned level the tripod. I use a Leofoto LB-75 levelling base between my tripod and the wedge (shown above) as this makes levelling much easier and quicker than having to adjust the tripod legs. The LB-75 and Star Adventurer 2i wedge both feature bubble levels so you can check as you adjust.
After levelling I recheck that i’m still pointed north and haven’t disturbed the tripod alignment.
Mount the Star Adventurer drive unit onto the wedge and tighten the clamp.
Fit the Declination bracket to the Star Adventurer 2i RA clamp and lock into place. I have an Arca Swiss clamp attached to the second screw mount on my Declination bracket so I can attach an iPhone to roughly polar align the mount.
Star Adventurer 2i mounted onto the EQ wedge and declination bracket fitted (note the additional arca swiss clamp on the bracket)
Declination bracket fitted with a spare l-bracket to hold an iPhone parallel to the axis of the Star Adventurer 2i
I use the PS Align Pro app to do the initial polar alignment. PS Align Pro has a daytime polar alignment function that allows a reasonably accurate initial alignment to be made before you need to start shooting. You need to mount the smartphone so that it points in the same direction as the mount.
Using PS Align Pro Daytime Alignment mode to roughly polar align the Star Adventurer 2i
PS Align Pro
Mount the camera and counterweight system as shown above.
Balance the RA axis. With the camera and counterweight in position fully loosen the RA clutch mechanism and rotate the RA drive until the counterweight shaft is horizontal. Check that the system balances properly. If the Star Adventurer starts to rotate adjust the counterweight position until it remains in position wherever it is let go of. Once correctly balanced return the drive so that the counterweight bar is horizontal and lock the RA clutch in place.
Balance the camera on the Declination axis. Fully loosen the declination clutch and adjust the position of the camera until it doesn’t rotate when let go of. This may require the use of a long arca swiss plate or lens foot in order to attain the correct balance point. I use a Kirk Enterprise Systems plate to allow me to balance the camera even with lenses that don’t have separate lens feet.
Loosen the RA clutch and balance the camera and counterweight
Loosen the Dec clutch and balance the camera on the Dec fine adjust base
Now everything is set up it is worth checking the polar alignment again using the smartphone and PS Align Pro app.
If you are using a relatively short focal length lens to take wide field images, say Milky Way nightscapes, this may be all you need to do to set up the Star Adventurer 2i. Just loosen the two clutches, point the camera to the area you want to shoot, and tighten the clutches. Remember to switch the Star Adventurer 2i into celestial tracking mode.
For deep sky objects (DSO) like galaxies or nebula where you need longer exposure times it may be necessary to carry out a more accurate polar alignment using the built in polarscope and separate illuminator accessory. I won’t discuss this here as there are many excellent YouTube videos explaining how to do this with the Star Adventurer 2i.
The Star Adventurer 2i in use
The following images are my first attempts at using the Sky Watcher Star Adventurer 2i to capture night sky images. All images are taken with my Nikon Z7ii mirrorless camera.
Milky Way rising above a snow covered Skiddaw mountain range in the Lake District.
Nikon Z7ii with Nikkor Z 24-70 f2.8 S lens at 40mm
Sky exposure: 120 seconds at f2.8 and ISO 800 (Star Adventurer 2i celestial tracking),
Landscape exposure: 180 seconds at f8 and ISO 800 (Star Adventurer 2i tracking turned off).
Andromeda Galaxy - M31
Nikon Z7ii with Nikkor Z 100-400 f4.5-5.6 S lens at 300mm
Exposure: 240 seconds at f5.6 and ISO 800 (Star Adventurer 2i celestial tracking), 16 image stack processed in Siril
Note that this image is after significant processing in the Siril astronomical processing application. I’m a complete beginner to using this software but I followed a step by step tutorial on YouTube by Kamil Pekala.
I would recommend following the video closely to understand how to use the software. In this case I first watched the whole tutorial video and then replayed it, pausing eat each step and then trying to follow it using my own images.
To give you an idea of how powerful the software is the image to the right is one of the individual 240 second images used to generate this version.
The Great Nebula in Orion - M42
Nikon Z7ii with Nikkor Z 100-400 f4.5-5.6 S lens at 300mm
Exposure: 100 seconds at f5.6 and ISO 800 (Star Adventurer 2i celestial tracking), 12 image stack processed in Siril
Again, to show how powerful Siril is the image to the right is one of the single frames used to create this photograph.
Conclusions
I really loved using the Sky-Watcher Star Adventurer 2i. The system is very easy to set up and use. The mount is small, lightweight and extremely portable so you can add it to your camera bag without too much trouble - the whole package including brackets and counterweight comes in at approximately 2.5kg. The unit’s low price is amazing for those that want to image both wide field tracked milky way nightscapes or some of the more visible deep space objects. Build quality is generally excellent as you would expect from Sky Watcher, but some of the components like the battery compartment cover, polarscope cover, and polariscope illuminator do seem cheap and are prone to falling off. This in no way affects the operation of the system though.
It really does open up a lot of opportunities for night photography.
If you have been thinking of getting into DSLR/Mirrorless based astrophotography I would highly recommend you take a look at the Sky Watcher Star Adventurer 2i. The Pro Pack, while being the most expensive package, provides a number of accessories that really enhance the system and is the one to get.