Beehive Cluster - first attempt

[Adreneline]

This is my first serious attempt at a cluster and I have found it really difficult to keep halos and star colours under control, and even now I'm not sure I managed it! To be truthful I've had lots of goes at M45 but been too ashamed of the resulting images to post them here; I clearly still have much to learn when it comes to clusters!

This is 10 x 60s of R, G and B taken with an ASI1600MM-Pro with Canon 200mm unguided on an iOptrom CEM25-EC. Pre-processed in APP and PI and finished in PS.

This is image is uncropped - other than registering edge effects. There are some dodgy stars in the corners which I am trying to sort; I can't decide whether it is spacing or something else. I've manged to resolve some of the doublets in the image (sort of) but not all and I'm not sure whether that is down to 'seeing' or lack of resolution of the camera/lens combination.

Plenty of room for improvement I fear.

Thanks for looking and all advice and comments welcome.

Adrian

[happy-kat]

Your star shapes look pretty OK to me.

Did you stop your lens down or use it wide open?

[johngm]

10 minutes ago, happy-kat said:

Your star shapes look pretty OK to me.

Did you stop your lens down or use it wide open?

I agree. When using lenses its always a good idea to drop them down a couple of stops.

John

[happy-kat]

Depends on the lens, I stop my 85mm f1.8 down to f4 but some are ok wide open.

[johngm]

1 minute ago, happy-kat said:

Depends on the lens, I stop my 85mm f1.8 down to f4 but some are ok wide open.

Yes, I here the Samyang 135mm f2 also performs well wide open. Hopefully ill be purchasing one this year.

[Adreneline]

17 minutes ago, happy-kat said:

Did you stop your lens down or use it wide open?

 

6 minutes ago, johngm said:

I agree. When using lenses its always a good idea to drop them down a couple of stops.

Thanks for the advice on stopping down the lens, a trick I can employ with my Samyang 135mm and 85mm but not the Canon - the Canon is a fixed 2.8 lens - there is no aperature adjustment - unless I am missing something  Mind you that does give the advantage of no spikes around the stars.

There are strange artefacts associated with the stars in the corners of the image. Each corner is slightly different so I'm struggling to understand what is the problem. Could it just be the lens optics? Alignment? Droop? Spacing? Really not sure. I've spent hours tweaking and adjusting all to little or no effect. I'm sure it is not the lack of guiding because when I do guide the artefacts are still there.  There is quite a difference in focus position for R/Ha/SII compared with R/G/OIII - perhaps more than I would have expected.

Thanks again for the advice and kind comments.

Adrian

[happy-kat]

You could stop down the lens using a stepdown ring. They screw into the filter thread but if your stars are generally good shape just cropping stacking edge artifacts away could be enough to tidy up most likely.

Could be the lens.

[Adreneline]

1 hour ago, happy-kat said:

Could be the lens.

I hope not 😟 - seems pretty unlikely I hope 🤔

1 hour ago, happy-kat said:

You could stop down the lens using a stepdown ring.

I did try (borrow) a step down ring but it was only a single stop step down and I couldn't detect any noticable improvement.

I am beginning to think it is a stacking issue. I can detect no difference between APP and PI but I have noticed that using drizzle in APP definitely helps (as I guess it would in PI). As you point out it is a pretty big FoV so losing a bit is no big deal.

Thanks again.

Adrian