Recently I moved house and acquired a darker site. So... I treated myself to a new scope- a Nexstar SE8 along with a GPS unit. This arrived after New Year in 2011 and initially I had the frustration and disappointment of having bought a dud. However, my replacement unit arrived this week and last night was my first opportunity to get out and use the scope.
It was a poor night for first light as the moon was just about full and most of the sky was awash with light. However, I got in a couple of 1 hour sessions and observed Jupiter, Uranus, the moon, and a selection of my old favourite double stars, M42 and a few of the more interesting asterisms. I thought it might be useful though to share experiences with the mechanics of the instrument.
The optics
The optics are first rate, as I would expect from Celestron. Images of Jupiter were clear and crisp, even with a 9mm Plossl Barlowed x2. Colours rich and views generally very pleasing (despite the wash of moonlight through everything). I am reserving judgement on DSOs as last night nothing was really viewable. Even M42 was rather washed out. Dew wiped me out after an hour- hence two observing sessions. I will need a dew zapper in the long run.
The mount
This is the drawback of the instrument. A one pronged "fork". There is significant vibration on focusing, but this dampens after 2-3 seconds so is tolerable. Otherwise I had no complaints. Once an object is in view it tracks efficiently and I was able to hold Jupiter in field for 15 minutes without even a minor adjustment.
The goto functions and alignment
This is the best bit. Once properly aligned the Nexstar worked like a dream. I could slew around the sky at random and it pointed just where I wanted it to. Over the course of an hour there was no appreciable loss of alignment, despite me banging my head on the scope and moving the tripod a little.
The key phrase here is once properly aligned. On my first venture outside it took 3 attempts to align despite the GPS. The GPS saves the bother of entering time date and location into the handset, but you still have to perform an alignment procedure. My first attempt was a lazy one- just aligning on Jupiter. This seemed to work, but although the scope could find Jupiter OK, nothing else was locatable and it missed the moon by about 20°! I tried again, using a 3 star align on Deneb, Rigel and Capella. This failed completely, at which point I twigged that the tripod needed to be perfectly level. Having sorted this out an alignment on Jupiter, Deneb and Rigel worked well. However, I was not completely level, so the goto was imperfect. On my second trip out, a perfect levelling of the tripod meant that a two star align on Aldebaran and Sirius was sufficient. This took all of 2 minutes. That's what I call easy set up.
So all in all, I am a) very pleased with the optics and more than satisfied with the Nexstar mount and control; and b) gutted that SCTs are so plagued by dew.
And someone do something about that dratted moonlight! :evil6:
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