Help with M42 and aligning with Deep Sky Stacker

[Will_]

Hi everyone,

Looking to get some help with aligning my raw images using Deep Sky Stacker. I am trying to work out if my tracking is too poor to align correctly or if its a settings issue on my end

I have followed several of the guides and videos linked here as well as some others I found on YouTube however I always end up with the same poor results

I use a Celestron C5 with a Canon 1200D for the photos - 30 second exposure (No darks/flats etc - could this be the issue?)

https://drive.google.com/drive/folders/11uRjXg9R1Uykev7UFwK50b0mNbFU7Nw5?usp=sharing

Above is the link for the raw files if anyone cares to take a look!

Also happy to provide any further information for setup etc if needed

Many thanks,

Will

[happy-kat]

Hi

what mount did you use?

The usual causes of DSS issues is poor focus or very elongated stars.

Putting a jpg image of one of your lights into your thread would be a quick way of getting feedback.

 

[malc-c]

Will, welcome to SGL.

Seems a lot of the subs have elongated stars, suggesting tracking / guiding issue.  As above, can you provide more info on the mount and your workflow, etc then we can offer more advice.  To me it looks like better polar alignment might give you more chances, but unless the mount is in the HEQ5 class or above, even 30 seconds unguided will give star trails, especially if your polar alignment is off.

Just to add, DSS is good, but no amount of correction will resolve poor initial images

Edited February 27, 2022 by malc-c

[Will_]

Thank you both for the feedback so far, it's already been very useful as it is starting to confirm my initial thoughts of poor tracking and focus not being perfect

I am using the standard motorised mount that comes with the Celestron C5 - very much not in the HEQ5 class! Also not using polar alignment and using the standard SkyAlign that comes with Celestron software - would polar alignment be more accurate despite the mount?

I have also attached a .jpg of one of the better light frames

With regards to tracking and the standard mount I am using, would reducing exposure times be useful or looking at a better quality mount a better option?

Thanks,

Will

[happy-kat]

That image has very useable stars so I would go to DSS and after registering untick the lights in your stack with a poor score, use the above as a guide for what a useable score looks like in your stack. also stack lights using kappa clipping and use intersection for the stack. Shorted exposure might help like 20 seconds also Orion is in the South now not best places if tracking is weak, East and West helps in the northern hemisphere.

[malc-c]

I've downloaded all 77 subs, and setting a threshold to stack only those that score 80% or above, 31 passed - the rest were rejected.  The resulting image wasn't great given it's just lights with no flats darks or bias images, and the stars still had a bloated appearance, but hopefully it will give you some encouragement - Here's a Jpeg cropped in Photoshop

 

Looking for the C5 it is often listed as a tube only, so no idea what "standard" mount you have, but looking at the regular rotation of the subs I get the feeling that it's not an equatorial mount ?

If you can inform us (or post up a picture) of the mount we can then advise further.  

 

[malc-c]

Now I'm no expert when it comes to imaging, but here's some of my observations based on the 77 subs..

Clearly there is field rotation suggesting the mount is an Alt/Az type rather than an EQ type.  This in its self is not an issue, but field rotation adds in one additional factor that the processing has to deal with, and that can lead to bloated or odd shaped stars.  It also means that polar alignment is not as precise as an EQ mount as you are reliant on the algorithms in the software once you've told the mount which stars you have aligned on.

Darks and flats would help with contrast and removing any rouge noise from the camera.

Not sure if guiding is an option as I think PHD2 only works with EQ mounts, but if that is possible, then using a guide scope and camera would / should keep the stars nice and round 

[happy-kat]

This is a relevant thread if you are using an altaz mount, plenty tips shared in this.

https://stargazerslounge.com/topic/228101-the-no-eq-dso-challenge/page/160/