NGC7293 - Helix Nebula - QHY247C

[Buzzard75]

NGC7293, The Helix Nebula
QHY247C w/ IDAS NBX filter
Astro-Tech 8" AT8RC w/ Teleskop 1.0x flattener
ASI178MC and Astromania 60mm for guiding
iOptron CEM40EC mount
Processed in Pixinsight and Photoshop
48x180s lights, 20x darks

Couldn't get flats or flat darks to calibrate correctly in Pixinsight for some reason. It would over correct and I would end up with a terrible gradient going outward from the center. I just gave up and tried to edit my dust donuts as best I could in Photoshop. Still having some drift issues with the mount and haven't quite got guiding nailed down yet. Just have to keep working at it. Thinking about getting a mono camera and a higher quality scope for guiding. Not sure it will make much difference though.
 

 

[AstroNtinos]

Magnificent image. Nice work.

[Adam J]

1 hour ago, Buzzard75 said:

NGC7293, The Helix Nebula
QHY247C w/ IDAS NBX filter
Astro-Tech 8" AT8RC w/ Teleskop 1.0x flattener
ASI178MC and Astromania 60mm for guiding
iOptron CEM40EC mount
Processed in Pixinsight and Photoshop
48x180s lights, 20x darks

Couldn't get flats or flat darks to calibrate correctly in Pixinsight for some reason. It would over correct and I would end up with a terrible gradient going outward from the center. I just gave up and tried to edit my dust donuts as best I could in Photoshop. Still having some drift issues with the mount and haven't quite got guiding nailed down yet. Just have to keep working at it. Thinking about getting a mono camera and a higher quality scope for guiding. Not sure it will make much difference though.
 

I dont think I can remember having seen anyone post images witht he QHY247C on SGL. I never really understood why it was not more popular as in theory its a great sensor as you show here.

Adam

Edited November 21, 2020 by Adam J

[Buzzard75]

3 hours ago, Adam J said:

I dont think I can remember having seen anyone post images witht he QHY247C on SGL. I never really understood why it was not more popular as in theory its a great sensor as you show here.

Adam

Thanks, and you're right. I was a little hesitant myself to get it at first because there really weren't a lot of people posting images from it either here, CN or on Astrobin. QHY camera posts are few and far between as it is. On paper though it is a really good sensor and QHY has put it in a really good camera. There's virtually no amp glow at all and it is an APS-C sized sensor with slightly smaller pixels than the IMX071, which is what's in the QHY168C and the ASI071.

[MartinB]

That's a lovely Helix.

I don't know what calibration routine you were using in PI.  You need your dark exposures to match your lights.  Make sure any "optimise darks" is unchecked.  Make sure your flat darks are being treated as darks, check the fits header and that batch processing hasthem in the right place.

[Buzzard75]

6 hours ago, MartinB said:

That's a lovely Helix.

I don't know what calibration routine you were using in PI.  You need your dark exposures to match your lights.  Make sure any "optimise darks" is unchecked.  Make sure your flat darks are being treated as darks, check the fits header and that batch processing hasthem in the right place.

Thanks! I'm running the same routine I've always run. They are the exact same exposure length, temperature and gain. I have never checked "optimize darks" before, but now I can't get them to calibrate any other way. If I leave it unchecked my calibrated image comes out pitch black even after a stretch. As for the flats, it seems to over correct during calibration. My dust donuts go from being dark to being the brightest part of the image and I end up with that gradient I mentioned where it's very bright in the center and extremely dark at the edges. It's almost like they're both having the complete opposite effect of what they should. I get the same issues in both DSS and Pixinsight so you're probably right that there is something wrong with the header information if it's doing it in two different programs. I'll have to look at the headers to see if there's anything obvious.

[MartinB]

The flat darks can be labelled as bias or darks in the fits header but not flats.  The optimise darks is for scaling darks which have a shorter exposure than the lights.  If the darks have the same exposure no attempt should be made to optimise them.  I've no idea why you end up with a dark image if you clear this box!  I am using the weighted batch processing script which has a check box telling PI to use dark flats.

[Buzzard75]

31 minutes ago, MartinB said:

The flat darks can be labelled as bias or darks in the fits header but not flats.  The optimise darks is for scaling darks which have a shorter exposure than the lights.  If the darks have the same exposure no attempt should be made to optimise them.  I've no idea why you end up with a dark image if you clear this box!  I am using the weighted batch processing script which has a check box telling PI to use dark flats.

Thanks, Martin! It really makes no sense to me. I'm not doing anything different than I was doing before on my last couple of images. I put up a new thread with some more detail outlining the issues in the Imaging Tips and Techniques section to see if anyone else has any ideas. I'm currently taking new darks so we'll see what effect that may have.