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Old 13-05-2021, 08:15 AM
enaiman (Eugen)
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Location: Hobart
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Carina Nebula with mirrorless camera

Waiting for clear skies, I am posting some old images I took with my Sony A7R mirrorless camera and the AltAZ mount.

This is a heavy crop (like a 25% of the whole frame) and you can still see the star trails even for those 60s exposures. While the stacking software takes care of the field rotation by aligning the images, it can do nothing about the rotation occurring during the exposure = star trails.
Seeing those images made me realize that the AltAZ mount was a poor uninformed choice and I need to get an equatorial one.

You can notice also all those stars - way too many - maybe my camera is to blame for this? I thought an astro camera might help with this and that's how I decided to get one (ZWO ASI294MC).

Any advice on improving future shots of the same nebula please?

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Old 13-05-2021, 08:29 AM
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Nikolas (Nik)
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Use an eq mount for starters that will make a massive improvement.
When you make the move to a dedicated camera make sure you utilise a light pollution filter like the L-Pro or a UV/IRcut filter to help keep star bloat under control. Obviously your processing skills then come to the fore and that will take time and lots of practise.
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Old 13-05-2021, 08:30 AM
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multiweb (Marc)
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Your focus is good so that's 99% there. It's quite a long exposure for an alt/az and because it's closer to the SCP you're bound to run into field rotation as well. It's hard to tell without seeing the whole field but it's probably a combination of things. Changing the camera won't resolve anything.

First thing would be to get a cheap star tracker or polarie so you can track the sky for 30s or 60s reasonably well.

From there on you'll be able to identify if you need to stop your lens further to mitigate coma or other.

That's where I'd start. But you're pretty close IMO. Keep at it.
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Old 13-05-2021, 11:08 AM
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rustigsmed (Russell)
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shorten the exposure length to 20/25 seconds you should have near to no trail (although will have field rotation so when you stack you will need to recrop the image.
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