Stars on Northern Thailand (using Vixen Polarie Star Tracker)
Last November (2012), I went to Nan, Northern Thailand to attend a family function. Nan is a small town with minimal light pollution, and is a fantastic place for stargazing. I spent two nights on the rooftop balcony catching the star lights.
I bought along with me two cameras, Canon EOS350D and 60D, Vixen Polarie Star Tracker plus a tripod and two ball heads. Since I need to travel around, I had to minimise my stuffs. This setup provided me with all I need to capture the stars, and at the same time, did not weigh me down, especially when I can replaced my bulky equatorial mount with a camera-body-sized Polarie star tracker.
During my two nights in Nan, and later one night in the nearby Doiphukha National Park, I dedicated one camera for shooting timelapse, and the other for still images. I used Polarie for two purposes: as tracking system, and for panning effect in timelapse.
The setup of Polarie was simple and fast. It took me less than 10 minutes to hook up everything onto the tripod. As I was in Northern Thailand (~19 deg N), Polaris was easily visible. I pointed the small hole (on the top right corner) to the star Polaris for polar alignment. When I looked through the hole, the field of view is relatively large compared to the star. Sometimes I was not quite sure if Polaris is exactly at the centre or not. For those who are not familiar using a telescope’s finderscope to search for stars may have difficulty trying to determine whether the star they are seeing through the hole is Polaris or not. But to me it was OK since I’m a seasoned telescope user.
First, I shot a wide-field view (FL17 mm) of Jupiter together with Taurus, Auriga and Perseus with exposure times of 1 min and 4 min. The tracking was good with slight but not obvious trailing of stars.
FL17 mm, 1 min (click to enlarge)
FL17 mm, 4 min (click to enlarge)
Next, I framed Orion with a higher zoom (FL50 mm). For a 3-minute exposure shot, the tracking was good with the stars showing some nice round dots. Signs of trailing started to show up in a 4-minute shot and became evident when exposure time is longer than 4 minutes. The reason may be due to the polar alignment inaccuracy as mentioned above, which will become noticeable as the focal length or exposure time getting longer. To solve this problem, Vixen has two optional accessories: the Quick Polaris Locator Compass and Polarie Polar Axis Scope. The Compass can also be beneficial when Polaris cannot be seen, for example if a tall building or trees is blocking the view of the north.
Orion, FL50 mm, 3 min (click to enlarge)
Orion, FL50 mm, 4 min (click to enlarge)
Orion, FL50 mm, 5 min (click to enlarge)
Polarie was also used as a panning device for my timelapse movie, and I just love the results. There are two scenes in the video below that showing the panning results by using Polarie. The first one is from 0:39 to 0:47, I was halfway through the scene when the clouds rolled in and forced me to terminate the sequence. The second one is from 1:52 to 2:31, taken in the National Park where the surrounding was full of trees. The stars were only visible on a small patch of sky above and between the some trees. Then I got this idea of moving my camera along the gap between the trees to capture the stars, and the result was, well, you can see for yourself in the video.
Stars of Northern Thailand
The Setup: one camera was mounted on Polarie and the other camera was mounted directly on the tripod. This setup was for shooting timelapse.
Lastly, I would like to talk about the battery consumption. Polarie uses either two AA batteries or an external power supply (such as a power bank through a mini USB port) as its power source. In my case, I used rechargeable AA batteries, and averagely it can last for 2 hours. I would like to note that I’m using old rechargeable batteries where their performance had already deteriorated. For new fresh batteries, it should be able last longer.
Overall, I’m very happy to have Polarie when I was out shooting. Its compactness makes my travel lighter and its ease of use makes my shooting session more efficient. I’m looking forward for my next night to use it again.
My Dark Sky 