Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: MarkS on Oct 09, 2008, 21:32:44

Title: M33 from Lydd
Post by: MarkS on Oct 09, 2008, 21:32:44

This is nowhere near as good as it could have been but here it is anyway.

Guiding was all over the place because the seeing was so bad.  But once stacked the problems are averaged out.
I forgot to put an IR filter in place and I think this may be the reason I screwed the focus up. In spite of all this, it does give some idea of what a DSLR can achieve.

Anyway:  19 x 5min Modified Canon EOS350D on Celestron C11 with F6.4 reducer.  Ambient temperature 9C.  This is the full frame with slight trimming and scaled down by a factor of 3 to help disguise the defocusing.

(http://gallery.orpington-astronomy.org.uk/albums/userpics/10046/m33_081008.jpg)
Title: Re: M33 from Lydd
Post by: RobertM on Oct 09, 2008, 21:39:31
Guiding all over the place maybe but it looks like a cracking shot to me !
Title: Re: M33 from Lydd
Post by: Rocket Pooch on Oct 09, 2008, 22:13:38
very good how's Lydd I personally like it there
Title: Re: M33 from Lydd
Post by: MarkS on Oct 09, 2008, 22:26:52

I saw the weather forecast and simply drove down for a imaging session after work.  I reckon the Lydd, Romney, Dungeness area is the darkest part of Kent (bar the odd power station!)
Title: Re: M33 from Lydd
Post by: Rocket Pooch on Oct 09, 2008, 22:47:24
yes and there is a camp site with a local Indian that delivers.
Title: Re: M33 from Lydd
Post by: JohnP on Oct 10, 2008, 06:07:01
Mark - a very acceptable result - looks very good to me. You really are getting some A1 results with that DSLR of yours.

John
Title: Re: M33 from Lydd
Post by: MarkS on Oct 10, 2008, 06:53:50

I'm still tinkering with that image.  Deconvolution is helping enormously.  I now need to remove those annoying background gradients caused by the focal reducer (always a painful exercise).

Here's an example on a different image:
(http://gallery.orpington-astronomy.org.uk/albums/userpics/10046/mini1.jpg)

The annoying (and difficult to remove) feature is that the gradient in the central disc is always in the opposite direction to the gradient in the frame as a whole.  Sometimes the gradients are left to right, sometimes up&down, sometimes diagonal - but they are always opposite.

I'm slowly creating a set of "master" backgrounds that I can subtract.
Title: Re: M33 from Lydd
Post by: JohnP on Oct 10, 2008, 07:17:56
Mark - have you tried GradientXTerminator by Russell Crowman. It's a plug in for Pshop it works great (although I must say my gradients are never as severe as yours). Only downside is it's not free.....

John
Title: Re: M33 from Lydd
Post by: RobertM on Oct 10, 2008, 07:51:55
I tried GradientXTerminator to on a demo license and it does work really well, definitely the best out there.  I have heard that some people even use it instead of flats.
Title: Re: M33 from Lydd
Post by: Rocket Pooch on Oct 10, 2008, 14:29:59
just looks like the light cone is smaller than the chip, your not going to do too much about that.  but I could be wrong?
Title: Re: M33 from Lydd
Post by: Fay on Oct 10, 2008, 14:36:28
That is fantastic Mark, if that is what you can get with guiding all over the place!
Title: Re: M33 from Lydd
Post by: MarkS on Oct 10, 2008, 23:09:49

Chris,  yes the light cone is smaller than the chip but there is still useful data outside the main light cone - I just need to remove the gradients to access it.

Robert, John,  thanks for the tip on GradientXTerminator by Russell Crowman.  I'll give it a whirl but I'm not that hopeful.  By the way, I loved his Gladiator film.

Title: Re: M33 from Lydd
Post by: Fay on Oct 11, 2008, 08:35:20
You're as bad at films as John! :P
Title: Re: M33 from Lydd
Post by: JohnP on Oct 11, 2008, 09:51:43
 :lol: :lol: :lol: Mark......

Fay - No one can be as bad as me....... I think you know that...!!!!!

John