North America Nebula NGC 7000 and Pelican

[Carole]

I could not resist the urge to go out last night despite a waning gibbous Moon, so pointed my scope in the opposite direction. 

Guiding was crap (but can we discuss this in a separate thread please).
Only 3 subs as the clouds rolled in. 
3 x 5mins ISO 800, flats, darks Canon 450D Modified, guided (Hmm)
Processed in DSS and photoshop.

[RobertM]

Other than needing flats applied it's very, umm, purple ...

[Carole]

Robert, it's got flats applied, the new style ones I did.  Yes I couldn't seem to get rid of the purple.  Do you think the colour overall is too red anyway?

[Daniel]

Carole, you've resolved the nebulosity well there, and with more subs you won't have to stretch it so much to pull out the detail, also as Robert mentioned, some flats would do this the world of good

Daniel
:O)

[Carole]

Other than needing flats applied

some flats would do this the world of good

There were 12 flats applied to this image!!  Should I have only used the same number of flats as subs (i.e.3)

I'm pretty disappointed with this as it could have been so much better
a) Because of the guiding.  b) Because after all the effort of setting up I only managed to get 3 subs.

But still pleased to have got my first NA nebula.  

it's very, umm, purple

Is this slightly better colour wise (or not).



Carole

[MarkS]

Carole,

You've chosen an ideal size of target here!  All the main features of the Nebula are visible - so very well done on that front.

It doesn't look as if flats have been applied.  Or maybe you didn't give DSS the bias frames and so it couldn't apply the right amount of correction.

There's also something really bad with the colour balance - far too red.  It may be that DSS has screwed up your data with some kind of colour balancing/scaling.  I had the same (horrible red) problem with DSS on one of the few occasions I've used it.  Duncan (AKA "The Thing") also created a DSS image with weird brown colours recently.

unfortunately, I'm not familiar enough with DSS to know what the issue might be.

Mark

[Carole]

Or maybe you didn't give DSS the bias frames and so it couldn't apply the right amount of correction.

Aha, just remembered I forgot to add a bias frame.  Might do a re-stack.

DSS was definitely processing the Flats. 

Maybe the red is me processing it too red. 

Carole

[RobertM]

DSS was definitely processing the Flats.

Should read...

DSS is definitely buggering up the Flats.

It is most definitely!!! Probably because of the Bias which should always be used with flats.  Not sure about DSS but MaximDL definitely needs them.

Too much RED, get the star colours looking right then it'll look more natural.

Robert

[Carole]

OK, I've done a re-stack and re-process this time remembering to apply the Bias frames and it has come out completely different with much less processing required.  It is interesting how much difference Bias frames have made to this.

[mickw]

Great improvement Carole

[MarkS]

That's much better - the flats are working now.  The colour is also looking better.  For 3 short subs from a light polluted area this is not bad at all!

The top left is still too black - you need to adjust the black level to bring out the detail here.

Once you've done this, you'll then notice quite a lot of backround gradient across the whole image that needs to be removed.  Such gradients are always expected when imaging in light polluted areas (even when using a CLS filter).  Unfortunately they are always a pain to remove.

[Carole]

Thanks Mark, some good lessons learnt there.  I'll have a go at the black level, but I already tried removing the gradient without success.

Carole

[Mac]

Good capture,

Colour balance,...............................your getting there.

Just need to add a few more light frames.
And get your processing up to scratch, still you do like a challenge . Light blue touch paper and retire.

Above all, you are getting images, so thats all that matters.

Mac.

[Carole]

Thanks Mac. 

I don't expect to get it all right first time, so long as the next time I do an object it is an improvement on the previous time I am happy, and hope to "get there" eventually.

Yes I do like a challenge. 

Carole

[Carole]

One last go at the processing before I put this one to bed.
Have reduced the gradient on the right hand side a little.