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Hi all. Thanks to Colin for his talk on polar alignment tonight. I think we touched on the subject of alignment where Polaris is not visible - but I’m not sure I quite grasped the conclusion. I’m in just that position (tall house, short south-facing garden), and given that limitation, I've concentrated on planetary & lunar imaging using a tracking alt-az mount - which is great, but I'm quite inspired by what I've seen in the GAS talks so far and would like to get going with some deep-sky work. So, I'm hoping for any for suggestions on practical (inexpensive!) ways of achieving polar-aligned tracking for photography. I’ve read up on drift method, but unless I’ve misjudged, it does sound quite onerous for something that needs to be set-up from scratch regularly (happy to be told I’m wrong!) Thanks in advance - all suggestions gratefully received! Keith |
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Hi Keith, It was an interesting session this evening wasn't it! Regarding your request, I wonder if it might be useful for the group to know what equipment you possess. That might allow answers to be aimed in a helpful direction, rather than sending you off to buy a load of different kit (!). Depending on what kit you have and what you would like to try to do, the answer might possibly be very simple and inexpensive - or it may not. As Colin has suggested, accurate polar alignment might not always be necessary. Especially for short exposures. It all depends. The main things to know would be what mount, what camera, and what telescope you have. If you're using a DSLR or similar, then camera lenses could be used too, so info on those would be helpful. Plus anything else that you think could be relevant. All the best, Tim |
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Hi Keith, As Tim says, a lot depends on what your kit is and what kinds of object you are trying to image. I now use a PoleMaster, which does depend on a view of Polaris, because it is quicker. However, before I got that I did use the Polar Alignment method in the guiding software PHD2. It did work quite well. The key point is that once you have the polar alignment 'correct' then you can make some marks on the ground (assuming concrete, patio, paving slabs or similar) and set the telescope up in the same position each time. Then you shouldn;t be too far off, and it might not take you too long, with practice to sharpen up the alignment. Jonathan (Clark) |
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Hi again, and thanks for your quick replies! I’ll try to add a bit more context… My current set-up works well for planetary imaging and visual observing - iOptron Alt-Az pPro tracking mount, C8 SCT, ZWO ASI178MC camera - but my assumption is that the alt-az mount will not support guiding needed for longer subs, and that rotation will be a problem anyway. I do also have the original (slightly elderly) Celestron German mount which has a simple battery clock drive - consigned to a box in the garage at the moment. I guess I’d like to be in a position to start using a modest (say, 60-80mm) imaging refractor to capture nebulae and star clusters, probably using whatever is a suitable camera (ZWO or otherwise). None of this has been acquired yet, but I was also expecting to have to buy a new mount. What’s been stopping me is the polar alignment question - which clearly I dodged for my planetary photography and visual observing by going the alt-az route. I don’t have experience with any guiding software. I hope that explains where I’m at right now! Thanks Keith |
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Hello Keith, Aha! It sounds like I was rather on the wrong track with what I was thinking. What I had in mind was that if your interest was in doing fairly modest things for starters, then crude alignment using a compass and a spirit level, or something along those lines, might have sufficed - please don't laugh too loudly at me everybody!! But it sounds like you're aiming a bit higher than that. I guess you're thinking that the original Celestron mount may not be up to the quality of tracking you are hoping for. And that it may not accept an autoguiding input, which may - or may not - be an issue. Anyway that's all rather beside the point of the polar alignment question. I have only ever polar aligned by looking through the mount's polar scope (apart from a few odd occasions with the compass and spirit level approach), and don't have any experience of doing anything more clever than that. So I'll step out of the way and defer to others who hopefully might be able to advise. All the best with your quest. Tim |
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Thanks, Tim. Yes, you're right about the old Celestron GEM - definitely a one speed clock drive only. As you suggest, I could try a compass and spirit-level alignment for some big-sky shots with a normal camera lens, and may well do so - but ultimately I think I'm aiming a bit higher. Thanks again, Keith |
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Keith, There is now a Plugin for NINA called: Three Point Auto Polar Alignment almost anywhere in the sky A new instruction will be available for the advanced sequencer as well as a new tool pane inside the imaging tab that will assist in polar alignment. When the instruction is called, a new window will be visible, that will guide you through the process. Inside the imaging tab there will be a button inside the tool pane to show the polar alignment assistant with parameters and a button to start the process. This claims to be able to do Polar Alignment from anywhere in the Sky. It is available from the NINA plugin menu or: https://theskysearchers.com/viewtopic.php?t=19968 Not tried it myself. Max |
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Thanks, Max. I suppose my main fear is that I invest in kit for guided long exposures that I can’t use - for lack of decent PA. But this does look promising and I’ll dig further. Keith |
