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Re: Camera names

Posted: Mon Sep 14, 2020 1:39 am
by Spidy
So this is the output from Astrometry.Net:

TAN-SIP Structure:
crval=(214.223, -78.3423)
crpix=(4083.59, 1564.51)
CD = ( -4.1979e-05 -0.00015821 )
( 0.0001584 -4.2077e-05 )
image size = (4944 x 3284)
SIP order: A=2, B=2, AP=2, BP=2
A = 0 0 4.3588e-07
0 -2.6604e-08
B = 0 0 -8.6068e-07
0 -4.6367e-07
AP = -0.00054225 -1.2674e-06 -4.3536e-07
-5.7127e-07 2.7623e-08
BP = 0.0016899 1.9908e-06 8.5959e-07
1.2606e-07 4.6069e-07
sqrt(det(CD))=0.589639 [arcsec]
Found tag-along columns from field: FLUX BACKGROUND
Field 1: solved with index index-206.fits.
Field 1: tried 1196 quads, matched 11212 codes.
Spent 1.748 s user, 0.068 s system, 1.816 s total, 1.84129 s wall time.
Writing 51 rows (of 2575 field and 53 index objects) to correspondence file.
cx<=dx constraints: 0
meanx constraints: 5205
RA,Dec constraints: 0
AB scale constraints: 0
Spent 1.84991 seconds on this field.

that's the tail end of the log file and what was displayed on the screen. Uhm, how do you read it? Am I even close to the SCP?

EDIT: Clicking on the Results link I got the attached image displayed. Looks like I was way off.

Re: Camera names

Posted: Mon Sep 14, 2020 7:54 pm
by admin

I think those numbers are mostly some of the technical details of the solving process – I'm not sure if they have the results inside them :(

However, the screenshot that you shared shows that your field-of-view was somewhere in the vicinity of Apus – that over 10° from the south celestial pole and too far away for SharpCap's polar alignment to work properly. You really need to be within 5° of the pole in your starting position for it to work nicely.

The trick with a strong is to wait until you see the success message and then click on the 'goto results page' link - that will take you to a page where you can see the full results
Capture.PNG (28.91 KiB) Viewed 736 times
Hope this helps, Robin

Re: Camera names

Posted: Tue Sep 15, 2020 2:07 am
by Spidy
Yeah, I had better success last night and actually got Sharpcap to resolve a plate solve. Couldn't get past the rotation step, so looks like I'll be buying a license.

Thanks again for your advice and your patience. :D

Re: Camera names

Posted: Tue Sep 15, 2020 6:39 pm
by admin

that sounds promising, but I'd like to check what you mean by 'couldn't get past the rotation step'. If that means that you successfully got a second measurement after rotating and SharpCap told you how far off your polar alignment is, then all is good and purchasing the pro licence will let you get to the final alignment step and polar line without any trouble. If you meant that you had a struggle getting the plates solving to work after you rotated, then I would suggest trying that bit again (maybe with longer exposure or more gain) until it works without any struggle.



Re: Camera names

Posted: Wed Sep 16, 2020 2:10 am
by Spidy
Thanks Robin.

I think I got as far as I could. I've attached a screenshot.
BTW, should I remove the ZWO ASCOM drivers am Sharpcap 3.2 uses the ZHO ASI drivers?


Re: Camera names

Posted: Wed Sep 16, 2020 5:58 pm
by admin
Hi Phil,

that all looks positive – from there you should be able to run the adjustment stage without any problems.

There's no need to uninstall the ZWO Ascom drivers really. You might find that you want to use them with another application. In general I wouldn't advise using them in SharpCap as letting SharpCap talk directly to the camera gives better control.

Cheers, Robin

Re: Camera names

Posted: Tue Sep 22, 2020 12:46 am
by Spidy
Yep, absolutely stoked with the result.

Just one more question if I may. On YouTube there are people saying your mount needs to be switched off while doing this procedure? I actually had CPWI running while doing this. I assume that was wrong?

Re: Camera names

Posted: Tue Sep 22, 2020 6:28 pm
by admin

to be honest it doesn't matter – the procedure only takes a few minutes during which time your mount won't move a great distance even if it's tracking. Since you're going to be looking at one celestial pole of the other (depending on your hemisphere) the actual movement of the stars due to the tracking is going to be minuscule.

Glad to hear that everything is working and hope you get some clear skies for some imaging :-)

Cheers, Robin

Re: Camera names

Posted: Wed Sep 23, 2020 2:26 am
by Spidy
Yeah, thanks Robin.

The next challenge is to star align the mount. Celestron has a procedure that uses their CPWI software but I'm not a fan of removing camera rig for eyepiece to align the star, rinse repeat three or four times, then put the camera rig back on.

Anyway, yet another challenge. I was warned that astrophotography was a marathon, rather than a sprint. And in my case, complete newbie with an f10 reflector @ 2350 focal length.....what was I thinking, lol.

Re: Camera names

Posted: Wed Sep 23, 2020 5:52 pm
by admin

if you have good polar alignment and minimal cone error then one point alignment is often sufficient for workable gotos - this is particularly true if you use the plates solving functionality as part of your workflow. That is tell the telescope to go to the target, except that it will miss and the target may even be out of view, use the GPS button in the SharpCap telescope controls to plate solve a frame, re-synchronise the telescope and go back to the target location which should put the target in view.

Of course, as you say, the long focal length makes all of this extra challenging – the small field of view makes targeting more critical and makes the plates solving harder to get working as you have fewer stars to work from in each frame.

Cheers, Robin