Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: RobertM on Jun 27, 2008, 11:05:36

Title: Cygnus widefield
Post by: RobertM on Jun 27, 2008, 11:05:36
This is my first DSLR Image with the 450d and stock 18-55mm zoom lens, there are a few more (hopefully better) images on the way.

(http://gallery.orpington-astronomy.org.uk/albums/userpics/10031/normal_DPP_0001_all_darksubtracted_27mins_p1.jpg)

Full details here: http://gallery.orpington-astronomy.org.uk/displayimage-503.html (http://gallery.orpington-astronomy.org.uk/displayimage-503.html)

It's a bit out of focus and noisy but I think the gradient is correct (Milky Way on the left).  The three brightish stars across the top (North) are the wings of the Swan with Gamma Cyg the middle star.

5 x 300s + 1 x 200s dark subtracted (seperate dark frames), no in camera NR used.

Mark/anybody - any comments on processing and lack of technique would be helpful.

Title: Re: Cygnus widefield
Post by: Ian on Jun 27, 2008, 11:13:15
just out of interest, why did you not use the in-camera NR? Is manual dark-framing better?
Title: Re: Cygnus widefield
Post by: RobertM on Jun 27, 2008, 11:33:44
Two reasons really ... the first and overriding was that it wasn't far off a full moon and I wanted to get some shots in before the sky got too bright.  The second was that all the camera does is to take a dark and do the subtraction for you, I took loads of darks at about the same temperature later in the week - I prefer more control.
Title: Re: Cygnus widefield
Post by: JohnP on Jun 27, 2008, 11:50:05
Not bad Robert for a first attempt.... a little too red for my liking but a good image. RU planning on imaging using something other than the stock lens?

John
Title: Re: Cygnus widefield
Post by: RobertM on Jun 27, 2008, 17:40:00
Yes John, I though it was too red to - hoping for so Ha subject to come through ... no chance !  After the other results from last week, yes, I'll be trying to sort out a few lenses - something like a 200mm then perhaps a 50mm.
Title: Re: Cygnus widefield
Post by: MarkS on Jun 27, 2008, 23:15:52

Im afraid I much prefer the Teapot image.  You're absolutely right with the processing though - forget about the in camera noise reduction and use many darks to make a master dark instead.

What was the ambient temperature when you took this (compared to the teapot)?  It's odd that they differ so much in quality.
Title: Re: Cygnus widefield
Post by: RobertM on Jun 28, 2008, 01:14:43
I found that I had the lens stopped down to F5.6 in this one with ISO200 rather than F4.5 and ISO 800 for the others.  Temperature actually increased from about 28C on the first day and must have been over 30C on the last night (midnight) but it was thankfully breezy most nights.

The stock lenses definitely aren't up to the job when you look closely though they do surprisingly well otherwise.