So, I took the plunge and bought a Skywatcher Star Adventurer Mini Wi-Fi bundle from Harrisons Telescopes.
For those of you who don't know what that is, it's a device that your camera attaches to so you can take long exposures of the night sky and at the same time keep the stars pin sharp. This is achieved because the "SAM" moves the camera at the same speed as the earth, thus following the stars across the sky instead of streaking them across your shot.
The SAM unit is controlled via an app available free for both Android and IOS. This app has various features including Astrophotography, Astro Time-lapse, Regular-Exposure Time-lapse, and Long-Exposure Time-lapse. There is also a manual control feature. The polar clock utility is used for polar aligning the SAM, which is surprisingly easy to do, even if you have never used a star tracker before.
In the bundle I got:
- The Star Adventurer Mini Wi-Fi (SAM)
- The equatorial wedge
- Ball head adaptor
- Polarscope & polarscope illuminator
- Dovetail L-bracket
The unit runs on 2 x AA batteries which seem to last forever. But, just in case you do drain the batteries, you can plug in an external power supply via the mini USB connection.
If you haven't already got a camera specific shutter release cable, such as the C3 for Canon or the N3 for Nikon, then you can purchase them from where ever you buy the tracker or, and probably cheaper, your local photographic dealer or eBay. This cable then plugs into the "Snap" port on the SAM and enables you to remotely control the shutter via the SAM Console Wi-Fi app.
To turn the SAM on press and hold the power button on the top of the unit. The red light will come on to show it is powered up and the green light will flash to show that Wi-Fi is on and ready to connect. Once you have connected via Wi-Fi the green light will stop flashing and remain on. When the green light is off this indicates that Wi-Fi is not turned on.
Also on the top of the unit are the basic polar aligning sights. You look through the raised round holes and place Polaris in the center. There are red lights to illuminate the sights to aid viewing.
Once the unit is connected to your phone or tablet via Wi-Fi you can control SAM using the various programs available in the console. These are;
- Astro Time-lapse
- Regular-Exposure Time-lapse
- Long-Exposure Time-lapse
Astrophotography is where you can take long exposures of the sky and SAM will track the stars using the sidereal setting and all the stars will remain pin sharp. Remember though, any foreground objects will blur due to the movement of the camera.
Astro Time-lapse is the same as normal Astrophotography except between each exposure SAM returns to the original starting point. When put together as a video it will give the effect of the stars moving across the skies while the viewing point remains fixed.
The difference between regular and long exposure timelapse is that you can't control the exposure time in regular mode with SAM (the camera shutter settings control this as it would normally). In long exposure mode you have to switch your camera to "bulb" mode and then set the exposure settings via the app.
The main menu also has the Manual Control option. This is where you use SAM to control the swing of the camera but operate everything else yourself via the camera.
The Polar Clock Utility is for advanced polar alignment using the polar scope and illuminator. Although it's advanced it is by no means difficult. Once you have got basic alignment via the sights on the top of SAM you then use the clock to determine where Polaris should be. After the app uses GPS to determine your exact location it will show you a dot on the clock, this represents the position of Polaris. Now, looking through the polarscope you just move the real Polaris into the same position as it was shown in the app, using the adjusting knobs on the equatorial wedge, and you're good to go.
I took the tracker out to the Angel of the North site to give it a quick test, not the best of places as there is way too much light pollution, but I wanted to give it a try out and didn't have time to go further afield.
As you can see from the images, it did an excellent job of tracking the stars and keeping them pin sharp. I did do an initial shot of the Angel in both these images to use as a sharp base in a composite, remembering that as you do a long exposure on the tracker any foreground subject will blur due to the movement of the SAM unit. So, in Photoshop, I just masked out the blurry foreground subjects to reveal the sharp versions.