As everyone who has owned a German equatorial mount (GEM) will know, getting polar aligned can be a challenge. Although a fairly close polar alignment is sufficient for observing, an accurate polar alignment is critical for astrophotography. Many GEM’s have a small polar telescope built into the mount, and this is used to align the mount. However, using this often involves having to get down on one’s knees, or even having to lie on the ground.
In order to avoid having to do this, and after reading several online articles and reviews, I purchased a second-hand QHY Polemaster from UK Astronomy Buy and Sell. This is a camera system which basically photographs the night sky around the Pole star Polaris. This short review will share my experiences with it so far.
On arrival, the first thing I noticed was that the supplied adaptor would not fit onto any of my current mounts. I therefore fashioned an adaptor with two vixen-type clamps and a spare dovetail bar. The advantage of this is that the camera can be moved up and down to ensure that the sky is visible no matter which type of telescope or mount is in use.
After downloading the software, I was keen to try it out, and did so on the first clear night which came along. I used my Losmandy mount and my 6” Achromatic refractor for the test. I started the software, entered the appropriate date and time, removed the camera dust cap and selected “connect camera”. The camera is very sensitive, and can pick out a lot of stars not visible to the naked eye, so I adjusted the gain and exposure settings to remove a lot of these stars, only leaving the brighter ones visible. The software then guides you through a process to help identify Polaris and surrounding stars. This process is a little too complicated to describe here in detail, but basically, ends with a circle containing a reticle on the computer screen. Polaris needs to be moved inside this circle using the altazimuth and altitude bolts on the mount. Note that, by this stage, the accuracy of the polar alignment is much greater than could be achieved by the human eye alone. After moving Polaris into this circle, alignment is complete. I then searched for some common objects in the sky using go-to, and I was delighted to see that every object ended up exactly in the middle of the field of view.
The time taken for the whole process was approximately ten minutes, but I reckon I can reduce this to five minutes with more practise. I would highly recommend using the Polemaster, as it saves time, reduces the need to scramble around on the ground using the optical pole finder on the mount, and is much more accurate than a traditional polar alignment.