Could anyone advise on this ???

[Stevie P]

Image of m31 (well sort of) taken on a fairly brightly moonlit night

45 30s Lights

25 30s Darks

No Flats (is this the problem?)

Stacked in DSS

Cropped (stacking artifacts)

Only one small level stretch in PS

Steve

My question is could somebody please advise on what the light rings are emanating from the center of image ? Please ignore dust blob top left.

Thanks in advance to anyone taking the time to help, Oh and answers would be helpful if in "Laymans Terms...".

Thanks Again

[Stevie P]

Sorry forgot to mention

Skywatcher 200p

Canon 1000D

[JamesF]

I think that's usually down to stretching an image with too little dynamic range. I'd probably go for longer exposures on M31. Was this with a DSLR?

James

[JamesF]

Aha!

I'd go for exposures of several minutes on M31 if you can. What mount do you have the 200P on?

James

[Stevie P]

Thanks James

Always on hand..

It was with a canon1000d

the rings can be seen in the original stacked tiff..

more-so after a tiny level stretch.

[VigdisVZ]

I've managed this earlier with 30sec subs on M31:

What ISO? Also how much have you stretched around in DSS?

[Stevie P]

Aha!

I'd go for exposures of several minutes on M31 if you can. What mount do you have the 200P on?

James

Skywatcher Heq5 Pro

[Stevie P]

I've managed this earlier with 30sec subs on M31:

What ISO? Also how much have you stretched around in DSS?

I took the image from DSS as is didn't mess with it at all..

[VigdisVZ]

Oh, sorry, that was the single sub, hang on...

This is what I did with 30s subs and darks. I still suck at processing, but you should be able to nudge a lot more out of it in DSS.

[VigdisVZ]

Here we go: http://flintstonestargazing.com/2009/06/26/my-quick-deepskystacker-tutorial/ There is a bunch of stuff you can and should do in the histogram in DSS.

Also at around 23 minutes in this video:

[JamesF]

Hmmm. Are you allowing DSS to apply its transformations to the image when you save it? I would generally tell it not to apply them and then deal with the stretching myself in PS or whatever other application you use for processing.

James

[Stevie P]

Oh, sorry, that was the single sub, hang on...

This is what I did with 30s subs and dark's. I still suck at processing, but you should be able to nudge a lot more out of it in DSS.

I can get more from the image but as I progress the rings get worse, Ive several ways of removing LP and gradients but with any more stretching the seem to reappear...

[JamesF]

It really does sound like insufficient dynamic range to me.

James

[Stevie P]

It really does sound like insufficient dynamic range to me.

James

I will have to have another go, next clear night and go for longer subs.

[JamesF]

Definitely worth a go. I'm sure the HEQ5 should be good for longer subs even with the 200P

James

[Stevie P]

Definitely worth a go. I'm sure the HEQ5 should be good for longer subs even with the 200P

James

I currently do not have the gear for guiding so spot on PA the order of the day, or I guess I will have to be prepared to scrap a lot of subs.... more hours in the garden..

[Stevie P]

Had another play, seemed to have got rid of white stuff, have to agree with James F not enough Data but looks a little better...Must try harder..