Sky Watcher Star Adventurer Preliminary Test results    

I already own two other commercial trackers, a Vixen Polarie and a Losmandy Starlapse as well as one I designed and machined for solar eclipse chasing about 23 years ago, several years before the current crop of mini trackers were released. Three weeks ago, a second hand Sky Watcher Star adventurer came up for sale second hand at only 40% of new retail price.  It arrived on a Friday afternoon at the beginning of September just at new Moon. When I received it, most of the original box seals were still in tact. I don't think the previous owner ever used it.  My Losmandy Starlapse is much heavier and sturdier than the  Star Adventurer and capable of handling heavier payloads. The Star Adventurer is more compact and better for light compact travel.
In the test exposures below, I polar aligned accurately then left the drive running but did not have an autoguider applying drive corrections.  I wanted to test the raw performance of the unit without tracking corrections.   Here are some preliminary results. I will perform and publish a fuller comparative review of the Polarie, Sky Watcher Star Adventurer, and Losmandy Starlapse over the summer.  If anyone out there has an iOptron Sky Guider Pro they'd be prepared to lend me, I'll add that into the comparison.

Setting up
I attached the altitude adjuster to a solid builder tripod. I have given this advice to many people in the past so I thought I should practise what I preach. It worked a treat and the setup was quite rigid.

Polar Alignment
The polar scope is optically not bad but as I had previously read and heard, the illumination is truly abyssmal. I might need to design and fabricate something better?

Nonetheless, I managed to put the polar axis close to spot on by using the 7th and 8th magnitude stars that are just a few minutes from the south pole. The "Trapezium Stars" are way out of the field of view of the diagram below. There was minimal declination drift on any of my test exposures, even those taken with a 135mm lens. 

 

Starting with a 14mm lens, I shot this Milky Way wide field with 2 minute exposures. High magnification examination of this image shows no drift, as it shouldn't.




Next I stepped up to a 135mm f2 lens.  In order to do longer 4 min exposures without overexposing, I set the ISO to 1600 and the Av to f5.6. At normal viewing magnifications, even larger than this, the drift is minimal. I was very pleased with this result.



In Lightroom, I magnified the above image to 1100%. Each pixel is now clearly visible in the extract below. The brighter stars are blooming (light is spreading due to overexposure) but looking at the fainter stars, the drift is only in the direction of star motion and not due to bad polar alignment. I checked using planetarium software. The error can mostly be attributed to periodic error. Over these 4 minute exposures, the drift is about 6 sensor pixels. Six pixels on my sensor with a 135mm lens works out to about ±20 arc seconds ( or about 1/90o ).



Over this summer, I will perform a more detail set of tests, different configurations, varying payloads and see what this little thing can do.

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