Alnitak...and friends

[Camelopardalis]

Folks,

This is a bit of a work in progress following a nomadic imaging feast last week :lol:

This is the area around Alnitak taken with a Canon 1100D (unmodded) and WO Zenithstar 71 mounted on an EQ6, unguided.

30x 2m ISO1600 subs taken from Bretti (+5 darks)
36x 5m ISO1600 subs taken from Wiruna (+7 darks)

Following recent threads on the subject, I've not used any bias frames.

There's a few things here for me to work on - notably the bloated and blue-y stars, and I think the nebulosity has some more to give :D

As always, suggestions/comments/etc on how to bring this out nicely greatly appreciated!

[cometcatcher]

It's a nice shot Dunk. :thumbsup:

Do you use photoshop for processing? If you want to shrink the stars a bit, go to - Select - colour range. Choose highlights. Go back to select - modify - expand by 4 pixels. Select - modify - feather 2 pixels. Then go to filter - other - minimum 1 or 2 radius. That shrinks them a bit.

[Camelopardalis]

Thanks Kevin!

Good stuff...I've given it a try and it does indeed shrink them a bit, leaving then mostly blue halos :sadeyes: maybe I should try this before stretching the curves?

[LightningNZ]

That's really smooth Dunk - those 5 minute subs from Wiruna really paid off.

Try to leave the curve adjustments near to last. Once you make the data less linear it becomes hard to apply other adjustments in an even fashion.

[cometcatcher]

Mmm, the dreaded CA. While the highlighted colours are still selected, go to image - adjustments - hue/saturation. Select the blue channel. Use the saturation and lightness sliders to reduce the blue fringe on the bright stars.

[raymo]

Very nice Dunk; I haven't had a go at that area since I graduated from
30sec subs.
raymo

[Camelopardalis]

Thanks Cam - indeed, the 5 minute subs here seem to work wonders :)

Noted - thanks. No doubt I will be posting a repro before long!



Yeah the blue halo only seems to be around the brighter stars :sadeyes: I'll give it a try, thanks Kevin.



Thanks raymo! It was as much by luck as anything else that I managed the 5 min subs, not sure I'll be able to do it again :shrug:

[Dealy]

Nice image Dunk.

I like it the way it is. :thumbsup:

Kev

[AstroJason]

That's turned out real nice mate. I like it a lot! Like Cam said, its really smooth.

I think you can bump up the saturation a bit without increasing the blue of the stars by masking the stars out.

[SimmoW]

Yeah really nice shot! Always room for improvement for all of us. Never ending!

[Camelopardalis]

Thanks chaps! It's the whiff of the challenge... :lol:

[Andy01]

Good job! May I also recommend these great and very inexpensive actions for PS? I use them all the time...
http://www.prodigitalsoftware.com/Astronomy_Tools_For_Full_Version.ht ml
Cheers
Andy

[nebulosity.]

Wow! Great job Dunk :thumbsup: That's really nice.

If you were feeling keen, you could even add a bit more punch. I reckon the data should handle it fine.

Cheers
Jo

[Camelopardalis]

Thanks Jo! A little more punch agrees with it :thumbsup:

[Amaranthus]

Dunk, on Bias, this is the basic story:

You should ALWAYS use Bias to remove the read signal from your Flats (which are then the denominator in the calibration equation).

If you use Darks, then you don't need the Bias subtraction sub-model (since the Dark contains both the dark current and the bias signal, both of which are then subtracted in unison from your Lights). Unless you are using a bad pixel map instead of a Dark, in which case the Bias is needed here too.

[Retrograde]

Lovely shot Dunk!

[Camelopardalis]

Thanks for all the help chaps!

A little more dust and a few more stars...