| Joined: | Mon Apr 2nd, 2012 |
| Location: | South Lakeland, UK |
| Posts: | 4066 |
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How many planar directions do you need for adjustment of the polar sighting scope?
Not quite sure what you mean, there are three adjustment screws in the 'scope, that in itself makes it a bit tricky to adjust, four would have been better, making the adjustment in two planes. The accuracy has to be very close. A star is tiny, I have to eliminate all tracking errors which enlarge or elongate the star, that is incredibly challenging.
The object of the accuracy of tracking is to allow long 'bulb' exposures of perhaps 30 minutes, currently 30 seconds is probably the limit for a reasonably sharp image. It's one of those exponential things where to double the accuracy you have to expend ten times the effort. Eventually you get to the Hubble stage.
If I could get stable five minute exposures I would probably be happy, I think that would bring the likes of the Orion nebula within my range of targets. I don't want to get into astronomy as such, would just like to be able to do a bit more than just star trails and Milky Way. I haven't even tried the fisheye on the mount yet. Up until now I have relied on star stacking software, I think combining the EQ mount with multiple short (30 second) exposures will be my optimum route.
Ah, I think I know what you mean now...
The wedge mount in the image above provides elevation on a horizontal axis and rotation on a vertical axis, it only requires those two planes of adjustment to align with Polaris. The adjustment has to be very fine. Impossible with a conventional video head or even worse a ball head. A large geared head would not be stable enough.
Whilst it is so windy you have a really tricky situation. Is there anyway that you can setup inside pointing out of a window?
I have considered that, I need my target at least a Kilometre away. I don't have a window which provides a suitable target. I am happy enough, I have shown that the adjustment had yielded improvement. I will just wait until the gales subside. Maybe next week? There are no clear skies in the current 14 day forecast but I have decided I need to accustom myself to the complexities of the EQ mount in daylight before attempting it in the dark again. It's one thing finding Polaris by eyesight, quite another with a telescope which inverts and reverses the image.
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Robert.