Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: Carole on May 23, 2011, 17:35:10

Title: M57 Ring Nebula 21st and 22nd May 2011
Post by: Carole on May 23, 2011, 17:35:10
My 3rd image from last night.  Due to cloud taken over 2 nights.

Total of 15 x 5min subs 800 ISO + darks flats and bias
Skywatcher ED120 Pro, guided with PHD and QHY5
Modified Canon DSLR EOS 450D + CLs Clip filter
NEQ6, and processed with DSS and PS CS3

(http://gallery.orpington-astronomy.org.uk/albums/userpics/10047/M57_Ring_Nebula_21st___22nd_may_2011_15_x_5mins.jpg)

Carole
Title: Re: M57 Ring Nebula 21st and 22nd May 2011
Post by: MarkS on May 23, 2011, 22:00:17

Is this a crop of the full-scale image?  Or have you re-sampled it to make it bigger?  It just seems a bit blurry.  The colour balance is good though.

Mark
Title: Re: M57 Ring Nebula 21st and 22nd May 2011
Post by: Carole on May 24, 2011, 08:50:00
It's a gigantic crop Mark, so much so I had to increase the resolution as you could see the pixels so on a DSLR that is a huge zoom. 

This is the full frame.  I guess at that level, any slight discrepancy in focus is going to be increased. 

(http://www.caroleastronomy.webspace.virginmedia.com/_wp_generated/wp00d88f78_0f.jpg)
Title: Re: M57 Ring Nebula 21st and 22nd May 2011
Post by: mickw on May 24, 2011, 09:46:50
Wouldn't your ETX do a better job with that ?
You could crop out any vignetting
Title: Re: M57 Ring Nebula 21st and 22nd May 2011
Post by: Carole on May 24, 2011, 11:03:28
QuoteInsert Quote
Wouldn't your ETX do a better job with that ?

You know I was just thinking the same thing myself Mick.  Means I'll have to do loads of subs to make up for the increased Focal ratio.  I'll have a go at that next time.

Guys, it is more subs or longer subs I need to do at F15?

Carole
Title: Re: M57 Ring Nebula 21st and 22nd May 2011
Post by: Mac on May 24, 2011, 11:21:42
Both.

Mac.
Title: Re: M57 Ring Nebula 21st and 22nd May 2011
Post by: Carole on May 24, 2011, 11:46:18
Thanks Mac, will give it a go and see how it works out.

Carole
Title: Re: M57 Ring Nebula 21st and 22nd May 2011
Post by: MarkS on May 25, 2011, 10:15:11
Quote from: Carole
It's a gigantic crop Mark, so much so I had to increase the resolution as you could see the pixels so on a DSLR that is a huge zoom. 

Carole,

If you've resampled the data to make your cropped image larger then that explains it.  There's nothing at all wrong with resampling an image but it does give it a more "blurry" appearance.  It doesn't mean your acquired data is out of focus.

Mark
Title: Re: M57 Ring Nebula 21st and 22nd May 2011
Post by: Carole on May 25, 2011, 11:18:02
Thanks Mark.
Is this better, I've done a larger crop and not increased the resolution this time.

(http://www.caroleastronomy.webspace.virginmedia.com/_wp_generated/wp1441c347.jpg)
Title: Re: M57 Ring Nebula 21st and 22nd May 2011
Post by: Carole on May 29, 2011, 18:34:21
Been introduced to Smart sharpen, to sharpen up images slightly out of focus.

(http://www.caroleastronomy.webspace.virginmedia.com/_wp_generated/wp04d13cec.jpg)
Title: Re: M57 Ring Nebula 21st and 22nd May 2011
Post by: mickw on May 29, 2011, 20:36:26
It's put haloes round the bright bits and stars  :-?
Title: Re: M57 Ring Nebula 21st and 22nd May 2011
Post by: Carole on May 29, 2011, 22:01:52
QuoteIt's put haloes round the bright bits and stars   
So it has.  Didn't notice that until you pointed it out, and even then had to look at the monitor from a different angle.

Oh well, back to the drawing board.

Carole
Title: Re: M57 Ring Nebula 21st and 22nd May 2011
Post by: Carole on May 30, 2011, 08:22:57
OK, one last attempt
(http://www.caroleastronomy.webspace.virginmedia.com/_wp_generated/wpf5f85a07.jpg)
Title: Re: M57 Ring Nebula 21st and 22nd May 2011
Post by: Fay on May 30, 2011, 16:54:39
Light bit looks too light, now :lol: :lol:
Title: Re: M57 Ring Nebula 21st and 22nd May 2011
Post by: Carole on May 30, 2011, 20:22:39
I think I did the adjustments to the Jpeg in error, will have one last try as soon as I get a chance.

Carole