Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: RobertM on Dec 06, 2011, 22:50:45

Title: Rosette from home
Post by: RobertM on Dec 06, 2011, 22:50:45
I took this the night before last ad had a hellish gradient to remove because of the moon.  It's taken the best part of tonight to sort that out so I've only applied histogram transformation and mild colour saturation post processing.

Taken with the C11 Hyperstar 570mm f/l, exposures 44 x 300s combined in Maxim with flats and bias.

First process:

(http://farm8.staticflickr.com/7035/6468385141_0a84c909c0_b.jpg)

Full size very slightly cropped: http://farm8.staticflickr.com/7035/6468385141_34e58ab4c8_o.jpg (http://farm8.staticflickr.com/7035/6468385141_34e58ab4c8_o.jpg)

Be patient if you have a slow connection as it'll progressively fill in the detail.

Yes, I know I still need to deal with the noise.

TFL Robert
Title: Re: Rosette from home
Post by: mickw on Dec 06, 2011, 23:17:26
Nice one Robert, very nice contrast.

Why are there spikes and why aren't they at right angles ?
Title: Re: Rosette from home
Post by: Carole on Dec 06, 2011, 23:42:37
Very nice Robert, looking forward to seeing the next process.

Carole
Title: Re: Rosette from home
Post by: MarkS on Dec 07, 2011, 07:27:30
That is an excellent result considering your level of light pollution and the moon - I can only imagine the gradients you must have suffered!

I assume this was taken using your SX M25C?  The image certainly vindicates your choice of a colour astro camera over a DSLR - I think the greater H-alpha sensitivity is certainly helping.  You've got me thinking ...

The processing is nice and contrasty.  I'd like to know how you manage to preserve contrast given such a high dynamic range.

Do you know the cause of the haloes around the brighter stars?  They were also in your Perseus image.  They are not objectionable, I just wondered what they were.

Mark
Title: Re: Rosette from home
Post by: Fay on Dec 07, 2011, 08:53:12
That is nice Robert, the Moon has been a nuisance, this week as well!!
Title: Re: Rosette from home
Post by: Mac on Dec 07, 2011, 09:11:32
very nice.

Mac.
Title: Re: Rosette from home
Post by: RobertM on Dec 07, 2011, 09:20:54
QuoteWhy are there spikes and why aren't they at right angles ?

Mick, that's because the two cables are not at right angles to each other.

Mark, yes it's the SX M25C.  The main difference for me are that the gradients are circular rather than rectangular (apart from the angled one from Tescos that is !).  Preserving contrast ?  Well I would put that down to the number of subs and gradient removal which allow more stretching of the image.  I also exclusively process in PixInsight now which has better tools.  The Haloes are probably reflections from the CCD chamber cover glass or LP filter.

Robert
Title: Re: Rosette from home
Post by: mickw on Dec 07, 2011, 11:36:54
QuoteMick, that's because the two cables are not at right angles to each other.

Sorry, I thought it was just one cable