| Joined: | Mon Apr 2nd, 2012 |
| Location: | South Lakeland, UK |
| Posts: | 4066 |
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Last night I went out again set up at Stickle Pike and took three series of images, firstly the Moon, just to test a theory, then I selected a bright object to the North West, not too high in the sky, then another bright object to the South East.
I set the Polar scope as best I could then rotated the mount arm around 360º which caused the polar star to appear to describe a circle around celestial North, by eye it seems pretty well centred on the celestial North marking. After I took the Moon exposures I again checked alignment, there was slight Polar drift so I corrected that and went for the first set of a star, may have been a Planet, I don't know...
I took about 70 exposures, 30 second intervals, checked alignment again, the Polar drift was so slight I left it alone. Then I made a second star set, same settings. Going through the sets the results are variable, some exposures are crisp and clean, others are mush. At the end of the session I again checked the Polar alignment and drift was very slight, Polaris had drifted from the centre of the tiny locating circle to the edge, which is measurable but insignificant for my purposes, in fact Starry Sky Stacker suggests a little drift is beneficial because it helps to cancel any noise. I have processed star 1 images and they are below. I have used Lightroom and Starry Sky Stacker free trial.
https://drive.google.com/file/d/18CE7amExArYwIvF5h0K0SBaEwjKrXSGb/view
Initially I tried to use Starry Landscape Stacker, by the same developer but it recognised that I was using an astro mount and warned by using the wrong version it could freeze the software because the algorithms are not intended to deal with that type of image. Amazing!
The composite image produced by SSS was made with ten selected 'best' images from 72, the images used spanned a period of 18 minutes of exposures, the first few exposures were not very good, I assume the mount needed to settle down.
Firstly the worst individual image from the set. These are at 100% crop.
The best individual image from the set.
The best individual image uncropped.
This is the final, cropped image made by Starry Sky Stacker from my ten selected best images.
As you may imagine I am delighted. I still need to more clearly understand how to get Polar alignment without groping in the dark! I will now go forward and finish the machining of the mount and refine some little niggles but essentially I have cracked it.
Will process Star 2 images later and post the results.
____________________
Robert.