Sadr Region in Cygnus

[Carole]

This is a messy looking area, but rich in gas and dust.  I was also pleased to get into the FOV the SpaceShuttle Nebula, one that has been on my list for some time.

Had some difficulty with focussing Blue and Green on the first night as was at the limit of the focus ring on the lens, it was almost perfect focus but not quite, so just had to make do with "almost there".  On the 2nd night however strangely all the filters focussed at the same point which sounds bizarre, but I have heard it can be temperature dependent.

So a further image with my Samyang 135mm F2 lens, but I stopped it down to F2.8
Atik460EX and Baader filters on HEQ5
Ha 900 x 8 & Ha 600 X 9 total Ha 3 1/2 hours
Oiii 9 x 300 binned (45m)
Sii 8 x 300 binned (40m)
RGB (for the stars) 12 x 200 each NOT binned.  Total 2 hours
Cloud stopped play on the 2nd night or would have got more Oiii and Sii.

Total imaging time (over 2 nights) 6h 55mins or 7 hours as near as damn it.

SEE POST 7 FOR REVISED IMAGE AFTER ROBERT'S CONSTRUCTIVE COMMENTS.

[ApophisAstros]

Amazing amount of shades and Hues ,
Roger

[Roberto]

Great shot Carole!  You have really mastered the wide field lens 

Roberto

[Carole]

Thanks Roberto.

Carole

[RobertM]

Nice capture Carole

BTW, you have some strange vertical lines at the top of the image which I haven't seen with a CCD before, any ideas on where they came from ?

Robert

[Carole]

Hi Robert,

I must confess I hadn't noticed them as they are only noticeable to someone as beady eyed as yourself, but I have stretched the image to show them better and it definitely looks like the effect BIAS sometimes has on my images, I recall having a conversation with you about this before.

As a general rule I tend to leave them out most of the time, but on this occasion I did include them and thought this was one of the occasions they worked OK.

As a point of curiosity I am going to stack and process again without the BIAS and see what sort of result I get then.  If it comes out without the lines I think i will have proved my point that BIAS does funny things to my images.

Carole

[Carole]

I am grateful to you for pointing this out Robert, and will now go back and reprocess the whole image, plus I have been meaning to try to construct an example of this behaviour for some time, so it has made me do it.

Herewith a crop of just the Ha -
top one WITH BIAS = has vertical lines
lower one WITHOUT BIAS = does not have vertical lines.

(I know the general processing is slightly different as would be expected starting from scratch with a new process)

(both lightened to show the lines).

Stacked in Astroart.



Carole 

[Carole]

Image now revised:

[MarkS]

Image now revised:

That's come out really well - nicely processed!

I don't think I know which area is the Space Shuttle.

Mark

[Carole]

Thanks Mark.

I don't think I know which area is the Space Shuttle.

To be honest, I am not sure if it is an official name, but I heard a few people call it that.

[ApophisAstros]

Can see that but i can see the face of Jesus
Roger

[RobertM]

That's much better Carole, I'm glad you got to the bottom of it.  I think the image is still suffering with minor gradients N/S (background is more blueish north compared with south) and star shapes but these are things we're all grappling with to a greater or lesser degree (you will see these more on widefield with our LP especially).

Hope that helps
Robert

[Carole]

Thanks Robert, yes I noticed the blue gradient in the final image which I got rid of the first time around, and missed the 2nd time, so I will attend to that.

Was just curious to know what you think about what the BIAS are doing to my images.

Carole

[RobertM]

Will take a look if you could you send me the master bias/dark and one light please.

Robert

[Carole]

I don't tend to save them, would have to reprocess and save them then.  Will let you know.

Carole