Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: MarkS on May 26, 2011, 00:48:29

Title: M13 - 24 May 2011
Post by: MarkS on May 26, 2011, 00:48:29
M13 from last night - a very quick pre-process - complete with satellite trails.

Modified Canon 350D on Tak Epsilon 180ED with IR/UV filter.
30 x 5min at ISO 800
10 x 150sec at ISO 100

(http://www.markshelley.co.uk/Astronomy/2011/m13_24052011small.jpg)

Full version is here:  http://www.markshelley.co.uk/Astronomy/2011/m13_24052011_full.jpg (http://www.markshelley.co.uk/Astronomy/2011/m13_24052011_full.jpg)
I fell asleep during acquisition and forgot to refocus with the falling ambient temperature - hence the squiffy stars on the right hand side of the full image.

Mark
Title: Re: M13 - 24 May 2011
Post by: Rocket Pooch on May 26, 2011, 07:29:32
Thats very nice.
Title: Re: M13 - 24 May 2011
Post by: JohnP on May 26, 2011, 08:45:34
That is looking good again Mark & great colours as well. Ton's of background fuzzies as well... Can't believe you have so many satellite trails....?

John
Title: Re: M13 - 24 May 2011
Post by: RobertM on May 26, 2011, 09:19:35
That's a really impressive result Mark.  I love the star colours.
Title: Re: M13 - 24 May 2011
Post by: The Thing on May 26, 2011, 09:23:53
Fantastic. Shows how important the scope is. No substitute for good optics.
Title: Re: M13 - 24 May 2011
Post by: MarkS on May 26, 2011, 09:55:39
Quote from: The Thing
Fantastic. Shows how important the scope is. No substitute for good optics.

Indeed, for full colour imaging you can't beat fast optics and dark skies.
Title: Re: M13 - 24 May 2011
Post by: mickw on May 26, 2011, 14:10:06
Great image but why are you getting 6 point spikes at the bottom of the large version ?

Title: Re: M13 - 24 May 2011
Post by: MarkS on May 26, 2011, 14:17:49
Quote from: mickw
Great image but why are you getting 6 point spikes at the bottom of the large version ?

When the DSLR mirror folds away during the exposure, it still sticks out far enough to interrupt the lightpath to that part of the CCD at a fast F-ratio of F2.8

A straight edge interrupting a lightpath causes a diffraction spike at right angles to the straight edge.
Title: Re: M13 - 24 May 2011
Post by: The Thing on May 26, 2011, 14:26:52
Fold it away - permanently :twisted:
Title: Re: M13 - 24 May 2011
Post by: mickw on May 26, 2011, 14:31:22
That's a bummer, only affects the bottom though luckily  :-?
Title: Re: M13 - 24 May 2011
Post by: Mac on May 26, 2011, 16:06:46
Stonking image.

Mac.
Title: Re: M13 - 24 May 2011
Post by: MarkS on May 26, 2011, 16:51:49

I have thought about removing the mirror entirely but I don't know of anyone who has tried it and I don't want to risk any unintended consequences.
Title: Re: M13 - 24 May 2011
Post by: PhilB on May 26, 2011, 17:30:39
I'd have to rate this image as the best M13 I can remember seeing!
Title: Re: M13 - 24 May 2011
Post by: Carole on May 26, 2011, 18:25:25
Amazing resolution, love those star colours.

Carole
Title: Re: M13 - 24 May 2011
Post by: Fay on May 26, 2011, 22:17:49
that really is great Mark!!!!!!
Title: Re: M13 - 24 May 2011
Post by: Whitters on Jun 27, 2011, 23:37:37
Jaw droopingly beautiful