Coal Sack to Carina

[Mickoid]

I took this over two nights this week between breaks in clouds from a Bortle 7 backyard. Tuesday night, 11 X 2mins @ 800iso with UVIR cut filter and Wednesday night, 20 X 2.5mins @ 3200iso 7nm Ha filter. Both with the modded Canon 550d and a 50mm lens mounted on a Sightron Nano Tracker. High cloud interfered with the Ha session on Wednesday night.

Processed in Deep Sky Stacker and blended in Photoshop.

[AlextheMartian]

Great framing of coal sack plus the running chicken and eta carina too. Nice job:thumbsup:

[multiweb]

Nice widefield. You've certainly picked up a lot of faint Ha neb between carina and the chook. Well done. :thumbsup::thumbsup::thumbsup:

[Merlin66]

Michael,
What f stop did you use on the 50mm lens?

[AdamJL]

that's great :) Lots of nice nebulosity there!

[Merlin66]

On the .jpg image, when plate solved and compared with CdC catalogues the limiting mag seems around 11 mag.
The reason for the interest in the aperture of the lens is to compare these wide angle shots with similar taken with objective gratings, which are only 25mm diameter.

[Mickoid]

Thanks Alex, by using the 50mm on a crop sensor this was all I could get in the frame at the angle I had the camera.


Thanks Marc, the UVIR cut filtered shots on their own looked a bit bland so it was nice to introduce a bit of Ha to spice it up!


Ken, I shot both filtered shots at f8.


Thanks Adam, it's always a struggle from light polluted skies to capture the nebulosity but the Ha filter really helped to show it up.

[Merlin66]

Michael,
Thanks for that.
That’s an effective aperture of around 6mm. I would like to think the 25mm grating could give useable spectrum of 6-7 mag target stars.

[Mickoid]

Correct me if I haven't understood what you're saying, is that my shot has picked up fainter stars at nearer to a 6mm grating than at the wider aperture of 25mm?

[Merlin66]

Michael,
Basically yes, a 25mm aperture has the potential to record fainter stars than a 6mm aperture.
With the spectral spread with say a 100 l/mm being 4 or 5 times, meaning a reduction in limiting magnitude by that amount.
What it infers, is that a grating could (I say could) record useable Spectra from target stars down to 6-7 mag stars.
I ‘ve setup a scope/ camera set-up which will hopefully show this.

[Anth10]

Very nice combination of data Mick, resulting in a pleasing wide field of the southern night sky. Really like the colour in this well done.
Anth