Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: RobertM on Jan 25, 2008, 21:25:16

Title: New mars image posted from last night.
Post by: RobertM on Jan 25, 2008, 21:25:16
Conditions were fairly breezy and not quite sure if I got proper focus.  Taken with C9.25@f20 but mars was only 50 pixels across - need to stack another barlow like Mark.  Have also posted a few frames of one of the AVI's to show what it was like at the telescope, these weren't bad frames either !

Robert
Title: Re: New mars image posted from last night.
Post by: Mike on Jan 25, 2008, 22:41:36
Where??
Title: Re: New mars image posted from last night.
Post by: MarkS on Jan 26, 2008, 09:44:35
This must be it - in the gallery:
http://gallery.orpington-astronomy.org.uk/albums/userpics/10031/K3CCD_0007_fewframes.avi (http://gallery.orpington-astronomy.org.uk/albums/userpics/10031/K3CCD_0007_fewframes.avi)

Robert, why is it only 320 x 240?  You ought to use the full resolution for shooting i.e. 640x480

You asked to see a few frames of mine.  It's here:
http://homepage.ntlworld.com/the_shelleys/photos/marstemp2.avi (http://homepage.ntlworld.com/the_shelleys/photos/marstemp2.avi)
It won't be there long 'cos it takes up too much room (1.3Mbyte)
Title: Re: New mars image posted from last night.
Post by: RobertM on Jan 26, 2008, 10:27:55
Taken in my garden in Orpington, I live about 1/2 mile west of the walnuts.

I've reposted a cropped part of the 640x480 image.  Before anyone remarks on the colour balance - I know it's way off.

Robert

Title: Re: New mars image posted from last night.
Post by: Ian on Jan 26, 2008, 12:14:57
not a bad go Robert. Colour balance is something to fix after stacking.

However, it does look over exposed to me. Mars, obviously, is very red, and it can be hard to spot when the red channel is blown. What software did you use to capture the avi? Some software (K3v3 -my favourite- can, there will be others) give a live histogram view of each channel separately. That way you can monitor if you've over exposed the red channel or not.
Title: Re: New mars image posted from last night.
Post by: RobertM on Jan 26, 2008, 14:06:57
Thanks Ian/Mark,

Comparing the few frames that Mark posted against mine I think Atmospheric turbulance was a major factor.  The scope is always outside under a light cover so should have been at ambient temperature but I did notice some dew on the corrector plate late in the sequence. 

It was captured with K3CCD.  Stretching the contrast I can now see that the red channel is very saturated, thanks for pointing that out Ian and your right it's not obvious.  That night was my first using K3 in anger and I still have a awful lot to learn.  Might have another go tonight if the weather is clear.

Robert