robrj
Member
Posts: 248
home town/country: Escondido, CA
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Post by robrj on Aug 11, 2016 18:43:50 GMT
Sharpcap 2.9 now has a Polar Alignment Tool built in. It uses plate solving (no internet connection needed) around the Polaris area. You need to be pointed to within 5° of Polaris.
It examines the sky and asks you to move the scope around RA. Then it generates a line with a circle at the end. Move the star at the end of the line to the circle. He recommends using a guidescope for a wider field of view.
You can access it via the "Tools" menu.
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Post by ChrisV on Aug 12, 2016 3:47:08 GMT
I've had a go with the polar alignment and did get it to recognise enough stars with my 80mm refractor, but only with big focal reduction so FOV > 1degree. Any FOV smaller than that it failed.
So I've just used the all-star-polar align on my celestron mount. It only takes a minute to do the ASPA after the initial star alignment.
Maybe i should revisit it. Do you do the polar align first ?
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Post by howie1 on Aug 12, 2016 4:53:28 GMT
Three things Chris ... 1. So as you are in southern hemi, then I take it you found SC has both the SCP PA stars / plates built-in? Right? 2. You mention you resorted to the ASPA routine after the initial star alignment ... so you did another star alignment too after the ASPA routine. Right? Cos thats the process ... star align followed by ASPA followed by another star align. Just checking 3. Given 2 above, I would imagine the SC routine is no diff ... star align followed by SC PA followed by star align. Right? Has to be, cos by doing the PA you are shifting the mount in Az and Alt and thus moving the internally and previously calculated star alignment positions in its 'brain'. cheers
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Post by ChrisV on Aug 12, 2016 8:45:27 GMT
1. Yes sharpcap has plates (or whatever they are called) for stars around SCP. The problem is it will only do it if you have FOV > 1deg. I've found it works a bit under that, but not much. So that's the problem with sharpcap polar align.
2. With ASPA some people to do another star align after the polar align and some don't. I've found its perfectly happy not to have it. I assume its little brain takes into account the polar adjustment. It might be a problem if you have higher magnification, but at my level its enough to gets stars near bang-on with the goto and the polar align near-enough.
So I just do - star align (2s stars + 3x calibration stars), then ASPA and thats it. - I make my last calibration star the one I'll do the polar align on. Its quick. - And on my first alignment star I set the focus and do an initial polar adjustment (as you suggested to me).
I prefer the ASPA to the polar align in sharpcap. But I haven't really used the sharpcap alignment so might not be the best judge. Might try it tonight while the moon is out and its too hazy to do anything else. Plus - too buggered to do anything else after a bad day at work.
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Post by howie1 on Aug 12, 2016 11:28:22 GMT
Thanks for the info Chris. Cheers
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Post by Dragon Man on Aug 12, 2016 12:18:47 GMT
Thanks Rob. Sounds like a handy addition to Sharpcap. It will make it easier to polar align for many people.
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robrj
Member
Posts: 248
home town/country: Escondido, CA
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Post by robrj on Aug 12, 2016 14:01:09 GMT
but only with big focal reduction so FOV > 1degree. Any FOV smaller than that it failed. I believe he recommended using something like an Orion 50mm guidescope for the polar align. That's what I used since I'm set up with that for use as an e-finder.
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Post by ChrisV on Aug 12, 2016 14:42:19 GMT
I'll have to get a guide scope going with a camera. I've just got a red dot finder on my scope.
Gave it a go tonight. Couldn't figure out the alt/az movements after i did the rotation !!!!!
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Post by Dragon Man on Aug 13, 2016 9:59:10 GMT
Hopefully the instructions will tell people to perfectly align their guidescope with their main scope first, then do the alignment. Otherwise the mount won't be polar aligned, only the guidescope will be, and if they change scopes the alignment will be out.
And even then you would hope that your main scope is exactly in line with the mount axis. Not all scopes are perfectly aligned to the axis because of slightly misaligned attachment of scope to dovetail bar etc. A Tube ring attachment on the dovetail rail being just half a millimetre out can put a scope out by many minutes of arc.
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robrj
Member
Posts: 248
home town/country: Escondido, CA
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Post by robrj on Aug 15, 2016 14:02:32 GMT
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Post by Dragon Man on Aug 15, 2016 15:17:47 GMT
Strange he would say that Rob. If you don't correctly align the scope with the mount axis once you change scopes the alignment would be different. Slightly, but different. If you don't change the finderscope used then all will be OK. Maybe someone may report that in their Beta tests.
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Post by Rick in NWArk on Aug 15, 2016 21:03:50 GMT
Figures. I bought the Pole Master and had to wait 2 months to get the adapter.
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Post by howie1 on Aug 15, 2016 23:24:22 GMT
I should write a sticky on PA having tried every method on the web and invented a few of my own over the years (the old bad neck and back problems so I dont use polar scope nor eyepieces - only cameras). Hence my interest in the SC version of PA. Love finding out new and varied methods.
Having said that, I'll stick with my handcontrol built in PA routines along with my 'trick' of doing the centering of the first alignment star with the Alt/Az bolts (not the HC buttons). Simple and easy, and no problems getting 10-15 arc secs and many times been down to 5 arc secs PA error. Most in my local astro club only use the HC built in PA routines and some of them go 5 min subs for AP. Autoguiders will tolerate and overcome PA errors of 30 arcsecs no worries. So IMO don't sweat total perfection for PA if you are guiding. And even if not guiding, it doesnt have to be total perfection. Especially if EAA'ing.
Rick, I see you bought PoleMaster ... did you ever try that PA method I sent you a link on for when you cannot see the polar area? I've taken the vid down as it was a very shaky iPhone vid - the first video I ever posted on YouTube actually? It was pretty neat and also aligned the OTA with the polar axis of the mount (like Ken says, unless you have that alignment there can be real problems).
cheers
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Post by Rick in NWArk on Aug 16, 2016 14:29:46 GMT
Howie, Yeah, I remember that video/method. I didn't get a chance to try it with my AVX before the mount tumbled from the Tripod and Broke. I actually got the PoleMaster to try to get my old SynScan mount to work but haven't had a chance yet (bad weather and working with my Evolution 9.25 on the couple of nights I have had). Honestly, I'm challenged at outreach events during the summer months when it gets dark so late. The attendees are there waiting and so there is a lot of pressure to get polar aligned quickly so I can get an image up on the screen and going. This leads to mistakes or skipping steps when people are talking to you and waiting for you to do this weirdly complicated task. By the way, someone mentioned global warming in another thread - I don't remember a summer having this many cloudy nights. It's been very frustrating. Lots of moisture in my skies on a regular basis. --Rick
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