Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: MarkS on Mar 29, 2008, 13:01:06

Title: M51 from France
Post by: MarkS on Mar 29, 2008, 13:01:06

I'm spending 10 days in SW France for Easter.  Weatherwise, the worst Easter I have known in France.

But last night (the 8th night!) the skies cleared enough to get 2 hours worth of 5 min subs over a period of 4 hours between the clouds.  The usual thing:  unmodified Canon EOS 300D on the C11 with a F6.3 reducer.  Guided by a 300mm Nikkor lens with an unmodified webcam stuffed in the back.

Maybe I can get some more data tonight.  This is still a work in progress - all I've done is a straight stack and some dynamic range adjustment.  Shown below is a crop of the fullsize image.  It's amazing what a difference dark skies make!

(http://gallery.orpington-astronomy.org.uk/albums/userpics/10046/normal_whirl280308.jpg)
Title: Re: M51 from France
Post by: Fay on Mar 29, 2008, 15:03:51
Wondered where you were, Mark. You have done well, yes, what a difference dark skies make! Look forward to the end product.
Title: Re: M51 from France
Post by: MarkS on Apr 02, 2008, 06:42:55
Now re-processed using IRIS.  I'm pleased with the result:

(http://homepage.ntlworld.com/the_shelleys/photos/M51_iris_280308.jpg)
Title: Re: M51 from France
Post by: JohnP on Apr 02, 2008, 07:32:48
Mark - that's brilliant - I'm not suprised you are pleased... It's amazing the images you are getting using a standard EOS300D..

Great shot - John
Title: Re: M51 from France
Post by: Fay on Apr 02, 2008, 08:09:16
I agree Mark, wonderful!
Title: Re: M51 from France
Post by: RobertM on Apr 02, 2008, 08:40:16
Another excellent image Mark, you never cease to amaze me what you can get from that camera.  If you ever fancy an upgrade then there's always one of these ...

http://www.centralds.net/en/index.htm (http://www.centralds.net/en/index.htm)
Title: Re: M51 from France
Post by: Mike on Apr 02, 2008, 09:00:31
Wow. That really makes a difference. That is an excellent image.
Title: Re: M51 from France
Post by: Fay on Apr 02, 2008, 09:04:44
What a camera, Robert, wonder how much it is
Title: Re: M51 from France
Post by: RobertM on Apr 02, 2008, 09:13:40
Approx $2400 inc. derivery :)
Title: Re: M51 from France
Post by: MarkS on Apr 02, 2008, 09:58:54
Thanks for all your positive comments. 

Robert raised an important and interesting point - cooling.  The ambient temperature was 8C when I took that image.  But CCD thermal noise doubles for each 6C temperature increase.  My calculations indicate this will have a noticeable impact on image quality in the summer months when the ambient goes up to 20C ( 4x as much noise ) or even 26C ( 8x as much noise ).
Title: Re: M51 from France
Post by: Tony G on Apr 02, 2008, 12:08:25
Lovely image Mark,

until you see images like this, taken with the Canon, you would be out buying astro-cams costing and arm and a leg, not knowing the full potential of the DSLR.
These images only encourage me to try, weather permitting :roll:

Tony G