Polar align cordinates

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dts350z
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Joined: Fri May 18, 2018 6:00 am

Polar align cordinates

Post by dts350z » Mon Jun 11, 2018 3:33 pm

in 3.1.5203 last night I tried the Polar Alignment.

I think there is a bug in entering the GPS position in the SharpCap settings. Over several tries pressing apply the changes were not reflected in the PA tool, even after restart. Changes didn't stick in the settings dialog either. At one point I noticed longitude had changed but not latitude. I finally got the latitude to change and stick by changing the drop down from North to South and then back to North again. The Apply button lit up as soon as I changed the from North to South.

Not a bug but an observation, like many people, I use an ST80 for guiding. As pointed out, 400mm FL vs. the recommended 200mm. A real struggle and I gave up and actually used a Polemaster camera with SharpCap, and it worked quickly and well. So left not sure how to advise my students with ST80s on PA with SharpCap, vs. buying a PoleMaster.

Also people with off axis guiders would be in the same or worse boat?

I do wonder if there is an inexpensive USB "board" camera and S mount lens (maybe ~$75US) that could be recommended to use with SharpCap PA vs. $300US for PoleMaster?

cuivenion
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Re: Polar align cordinates

Post by cuivenion » Mon Jun 11, 2018 4:16 pm

You could try using a 0.5 reducer with the ST80.

dts350z
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Re: Polar align cordinates

Post by dts350z » Mon Jun 11, 2018 6:35 pm

Yeah but I think messing with a dialed in and cinched down autoguide setup to do PA is a bad plan.

Going from the 50mm guide scope to the ST80 usually gives people a 2x improvement in guiding so I still think 400mm and 80mm dia is the way to go for a guide scope with large FL reflectors. FYI Orion stopped offering the ST80 but you can now get it from iOpteron.

From watching one of my students struggle with 200mm and SharpCap I'm thinking a dedicated smaller FL for PA is needed. I just hope it can be inexpensive.

dts350z
Posts: 34
Joined: Fri May 18, 2018 6:00 am

Re: Polar align cordinates

Post by dts350z » Mon Jun 11, 2018 7:08 pm

FYI my FOV is 30.9 x 41.2 arcmin so just at the recommended 0.5 degree.

1.93 Arcsec/pix.

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admin
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Re: Polar align cordinates

Post by admin » Mon Jun 11, 2018 7:34 pm

Hi,

so as far as I can see there is an issue if you have already used the polar align tool then goto the settings and change them then the new values will not take until a restart - I will fix that.

There is also a separate issue where you have to (at least) click on another control in the settings window before the apply button lights up if you have just changed one number. This isn't normally a problem as you would typically set both lat and long, and once you have set the longitude and moved to the latitude box the apply button will come on. Anyway, I will fix that too :)

You can definitely buy a reasonably cheap board camera (even with the AR0130 sensor used by many guiders), but the one I have only goes to 0.5s exposures, which may not be enough for polar alignment (2s is usually a good starting point).

As to using a cheap lens, they seem to get rather expensive as you get beyond about 50mm focal length for CS thread lenses. 50mm might work though with a standard guiding style camera, but you also have to work out a way to mount the lens/camera firmly. Plenty of companies are starting to sell 130mm mini guiders which seem to work well.

cheers,

Robin

dts350z
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Joined: Fri May 18, 2018 6:00 am

Re: Polar align cordinates

Post by dts350z » Mon Jun 11, 2018 11:32 pm

Do we know if the CELESTRON NEXIMAGE BURST CAMERA - MONOCHROME supports > 1 sec exposure?

That's the AR0132 sensor.

A little more pricey than I had in mind but if that's the minimum it takes...

Also I found a page that is supposedly all long exposure CMOS USB box cams, but I can't find any pricing anywhere.

https://en.ids-imaging.com/store/produc ... 30000.html

and

https://en.ids-imaging.com/techtipps-de ... osure.html

dts350z
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Joined: Fri May 18, 2018 6:00 am

Re: Polar align cordinates

Post by dts350z » Tue Jun 12, 2018 4:09 pm

Re the Celestron Nextimage burst, I see this comment about long exposures:

https://www.cloudynights.com/topic/5064 ... try6691993

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Re: Polar align cordinates

Post by admin » Tue Jun 12, 2018 6:27 pm

Not sure about that model, but when I had some Celestron cameras to test I seem to recall that the max exposures were quite limited, so be careful!

cheers,

Robin

dts350z
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Joined: Fri May 18, 2018 6:00 am

Re: Polar align cordinates

Post by dts350z » Wed Jun 13, 2018 5:36 am

OK thanks.

Could we live stack to enable a cheap (short exposure) camera to be used for PA?

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