A few issues with this image, any ideas?

[bendiddley]

Went out last night and got first light on my new Skywatcher 72ED. Great to be out as its been a while.  Managed to get some data which I processed today. As you can see there are a few issues going on and wondering what might be the causes. Things I notice are the stars are bloated, the large stars have halo/discs around them, the detail is a bit fuzzy even though I made sure the focus and PA were spot on, it's also become quite noisy. Here's a full list of the set-up...

Scope: Skywatcher 72ED with .85x focal reducer
Mount: NEQ6
Camera: Starlight XPress SXVF-M25C colour CCD
Data: Lights 22 x 300sec, Bias x 25, darks x 25, flats x 25
Stacked with DSS, processed in photoshop

[ONIKKINEN]

For the noise you need to expose longer, a lot longer. Your camera (from what i could find) has read noise in the range of 7e- to 12e- and your 300s subs are definitely not long enough to account for that. The exact length of exposure that is enough to cover that depends on your sky conditions, but i would guess you need to go at least 10 minutes to get significantly less noisy results. The same applies for your calibration frames, the more you stack them the less you add noise in from them. 25 is not that much, you would do well to at least double that number.

[david_taurus83]

I would say that perhaps your stars are a tiny bit out of focus, just. Which may give the appearance of bloating. Then again, does the 72ED use FPL51 glass? Regarding the offset halos, did you use a filter? I get this type of halo on my Redcat if I use a filter.

[bendiddley]

42 minutes ago, david_taurus83 said:

I would say that perhaps your stars are a tiny bit out of focus, just. Which may give the appearance of bloating. Then again, does the 72ED use FPL51 glass? Regarding the offset halos, did you use a filter? I get this type of halo on my Redcat if I use a filter.

Thanks. No filter used. Not sure what the glass is, the retailer I purchased it from doesn't specify it, or do other places it seems. Maybe there is a focus issue however the central spike on the bahtinov was right in the middle.

[bendiddley]

58 minutes ago, ONIKKINEN said:

For the noise you need to expose longer, a lot longer. Your camera (from what i could find) has read noise in the range of 7e- to 12e- and your 300s subs are definitely not long enough to account for that. The exact length of exposure that is enough to cover that depends on your sky conditions, but i would guess you need to go at least 10 minutes to get significantly less noisy results. The same applies for your calibration frames, the more you stack them the less you add noise in from them. 25 is not that much, you would do well to at least double that number.

Thanks for that. I will definitely try stacking more calibration frames next time, maybe give the lights more time too.