AA26C, AAGPCAM 130M and Polar Alignment Struggle

Using SharpCap's Polar Alignment feature
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Brian1973
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AA26C, AAGPCAM 130M and Polar Alignment Struggle

Post by Brian1973 »

I recently upgraded my mount to a SkyWatcher EQ-6 R Pro. I also switched from using a Canon T6I to the AA26C as my main imaging camera. For the past few imaging sessions, when using Sharp Cap for polar alignment, I noticed Sharp Cap will automatically max out the gain level for the AA26C when engaging in the polar alignment process. My exposure time is set to 15 seconds. I have tried to reduce the gain level but PA will not pick up enough stars until I reach a gain level of 700 or more.

In addition to maxing out the gain level, after much trial and error, I have to set the sensitivity level to 97 to be able to detect enough stars for polar alignment to function.

Even when I am using this numbers I have also ran into the issue, after adjusting the altitude, for some reason the "UP" number remains the same while the AZ will be adjusted. It presents as frozen. Adding to all of this, it takes several minutes when using the AA26C to pick-up enough stars to begin polar alignment.

The other night I tried for the first time using my guide scope (AA 60m) along with my guide camera- GPCAM2 130M Mono CMOS Camera (225mm Focal lenght). Using the guide scope for PA went very well or so I thought. I don't think it was accurate because after achieving PA, I tried slewing to M31 and it wasn't there. I have been involved in astrophotography for a couple of years now and experienced with polar aligning an equatorial mount (my prior mount was a Vixen GP2).

My question is- Are the gain levels on the AA26C correct for PA? Any suggestions on how I can improve. I am attributing my struggle to operator error, lack of proficiency with a dedicated astro-camera.

Thank-you

Brian
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Re: AA26C, AAGPCAM 130M and Polar Alignment Struggle

Post by admin »

Hi Brian,

I wonder if the field of view on the AA26C is a bit large? What telescope do you have it connected to? The symptoms of the value being stuck are usually associated with SharpCap only being able to plate solve a frame intermittently, which can be caused by too small or too large FOV or not enough stars.

There are some guidelines here to help troubleshoot : https://docs.sharpcap.co.uk/4.0/#Troubl ... 0Alignment

Your guide scope/GPCAM should give good results - certainly accurate to sub 1 arc minute. Do check that the cable is tied back and that the guide scope does not flex as the mount is rotated, as both of these can lead to errors. Also a missed GOTO can also be caused by a slightly incorrect home position or cone error.

cheers,

Robin
Brian1973
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Re: AA26C, AAGPCAM 130M and Polar Alignment Struggle

Post by Brian1973 »

Hi Robin,

Thank you for getting back with me and your feedback. The telescope that I use is a Stellervue 80ED Focal length is 560.

Best,

Brian
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Re: AA26C, AAGPCAM 130M and Polar Alignment Struggle

Post by admin »

Hi,

the field of view should be fine then - it's about 2.4 x 1.6 degrees, which is a bit higher than average but not too high.

If you see the problem again, keep an eye on the 'Most Recent Frame' status - if you are seeing 'could not solve' more than once every now and then, save a frame using 'snapshot' and post a copy (share via dropbox, etc) so I can investigate.

The only other suggestion is to try using 2x2 or even 4x4 binning - I don't usually test with such a high resolution camera, so if it is anything related to the resolution, binning might help.

cheers,

Robin
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