IC5146 - The Cocoon Nebula

[mickw]

So 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 

[MarkS]

So 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

[MarkS]

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

[PhilB]

So 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?

[MarkS]

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

[PhilB]

Oh, I see 

Thanks, Mark. I understand now.

[The Thing]

Shame there is so little green light in the firmament.

[Rocket Pooch]

Hmm, is there not?