The Cocoon Nebula taken on two nights (2 & 3 August 2010) from Riberac, France. Taken early in the night before the moon became too troublesome.
H-alpha modified Canon EOS 350D on Banana Scope (Tak Epsilon 180ED at F2.8 )
33 x 5 min at ISO 800 + 3 x 5 min at ISO 100
(http://gallery.orpington-astronomy.org.uk/albums/userpics/10046/normal_cocoon03082010.jpg)
Larger version here (2/3 scaled):
http://gallery.orpington-astronomy.org.uk/albums/userpics/10046/cocoon03082010.jpg
Mark
Nice one
Are the stars a little bloated on the large version or are my eyes buggered ?
cannot believe how many stars are in that area. Very nice Mark. Great dark lanes
Wow!!! that's nearly perfik !!!
Excellent job Mark, though I suspect good data helps a bit ;-)
Robert
Hi Mark,
Very nice :-) do you know why the stars are a little fuzzy? Also I did see a picture somewhere with the head of the nebula in the bottom left and the dark tail goes on for ages.
Chris
Thanks for the comments.
Mick, Chris - I don't know the exact reason for the "fuzzy" or "bloated" stars but it's probably something to do with my processing - I found it difficult to bring out the dark lane without bloating the stars.
Chris - you're right - Barnard168 (the dark lane) does extend even further. In hindsight I should have framed it with the Cocoon further down and left in the image.
Mark
Hi,
It is a great image Mark, I'm wondering what to do next so people go wow, your kinda hogging it all.
Chris
You could always run naked through the fields, chasing black sheep, I bet that would make a few people go 'WOW!!!!'
Thinking about it, I think thats been done at Tuesnoad. :-?
Tony G
Quote from: Not Space Dog anymore on Aug 15, 2010, 22:09:52
It is a great image Mark, I'm wondering what to do next so people go wow, your kinda hogging it all.
Sorry mate - I didn't mean to hog the whole Universe! :D
The Achilles heel of my setup is that I'm essentially restricted to RGB. If you pick a subject that looks spectacular in narrowband with false colour (e.g. using the Hubble palate) then I won't be able to touch you!
Mark
Good, that means I just need to break Robert's kit then.
:-)
I thought I'd done this, this was with an HX916 Mark, with an ED80, your FOV is amazing.
(http://farm4.static.flickr.com/3237/2482390969_d6c7cd8e59.jpg) (http://www.flickr.com/photos/13007140@N05/2482390969/)
Cocoon-20070912 by chrissuddell, on Flickr (http://www.flickr.com/photos/13007140@N05/2482390969/)
Chris,
The FOV is due to the big CCD.
If you try the Cocoon again with your latest astro-camera on your ED80 with focal reducer, you'll get a field of view almost as large.
Mark
Quotethat I'm essentially restricted to RGB
Just curious..........
If you were to set the DSLR to B/W mode then use a narrow band filter could you then process that data as true narrow band to supplement the RGB or is the CCD not sensitive enough ?
Quote from: mickw
If you were to set the DSLR to B/W mode then use a narrow band filter could you then process that data as true narrow band to supplement the RGB or is the CCD not sensitive enough ?
A DSLR does not have a true B/W mode - the CCD pixels each have a permanent R, G or B filter on them. So if, for instance, I use an H-alpha filter then only the "red" pixels will react since the H-alpha wavelength is red. So only one quarter of the pixels will be of any use. It is still worthwhile to do this (indeed I have taken some H-alpha images) but it is far better to use a dedicated B/W astro-CCD where all the pixels will receive a useful signal.
Mark
Excellent image Mark,
I take where you are in France helps in the clarity of the image?
I wonder what my 350d will produce when we go in September.
I can only dream of images like the ones above, and many more within the society, but maybe one day I can get somewhere faintly near these.
In the meantime I'll make use of what I have.
Tony G
QuoteSo only one quarter of the pixels will be of any use
Does that simply mean exposures would need to be 4x longer ?
I'll ask no more questions in case I'm accused of a hijack ;)
Quote from: mickw
QuoteSo only one quarter of the pixels will be of any use
Does that simply mean exposures would need to be 4x longer ?
Broadly speaking, that's right, yes.
Mark
Tony,
Being in France certainly helps. My place there is slightly darker than Kelling Heath which in turn is quite a lot darker than the Rother Valley campsite. Even so, light pollution is the main limiting factor.
You will be down in the Alps - which should be very dark. Down there, the DSLR dark current (thermal noise) will be the main limiting factor. Do you use guiding yet? If you can do 5 minute (or longer) guided images then there is no reason why you shouldn't catch a stunning image or two with your DSLR. Just choose a target suitable for your scope focal length. If your 350D is unmodified I would recommend a galaxy e.g. Andromeda or Triangulum or a reflection nebula e.g. Pleiades. If yours is modified, then try a something with H-alpha nebulosity. Other folks may have additional suggestions. Then collect as much data as possible - a few hours worth (this is the key thing that makes a huge difference) - you can collect it over a couple of evenings.
Then you just have the pain of processing it all! But you can do that at leisure, back at home.
Mark
Quote from: MarkS on Aug 16, 2010, 16:27:47
Quote from: mickw
QuoteSo only one quarter of the pixels will be of any use
Does that simply mean exposures would need to be 4x longer ?
Broadly speaking, that's right, yes.
I guess I ought to know better than to query you on a point of math, Mark, but if you have pixels sensitive to red, green or blue, then surely red light is sensed by one third and not one quarter of the chip?
Quote from: PhilB
I guess I ought to know better than to query you on a point of math, Mark, but if you have pixels sensitive to red, green or blue, then surely red light is sensed by one third and not one quarter of the chip?
The pixels are arranged in 2x2 blocks as follows:
RG
GB
So, one quarter are red, one quarter are blue and half are green.
Mark
Oh, I see :oops:
Thanks, Mark. I understand now.
Shame there is so little green light in the firmament.
Hmm, is there not?