Eta Nebula

[vlazg (George)]

Hi All,
I took this image last night, only managed 3x5min subs before the clouds came in.
No darks , flats or bias- processed in Nebulosity with a slight tweak in PS
Es 80, atik 383c,ccd temp -4.7, 50mm guidescope, ssag

Mainly i was just testing my alignment with the advice i received in another thread, (Alignment help ). Thanks to those who gave advice the phd graph was great, showing about 4-6 arc seconds adjustment. This is the first time i have achieved anywhere near a good polar alignment. My 1st image using an equatorial setup, the others (3) were with alt-az with 10-15sec exposures. Due to the small window i have where i live in a suburb in Darwin i am not able to use Alignmaster, drift etc so i am happy with this, i am trying to get my head around this so i don't waste any time when i get to a dark site.

My main question is could any body please explain why the image is blurry, egg shaped stars, on the left of the image whilst the right side appears ok. Is it the image train, do i need flatterer (although i would have thought i would have egg stars in the periphery of the image)

Secondly any thoughts on how to further process this, most of the images of eta are reddish, how do i bring this out



George

[traveller (Bo)]

Good stuff George,
Are you imaging with a reflector? Looks like coma, so you will need a coma corrector to get a flat image, otherwise you need to crop.
Bob

[vlazg (George)]

Bo, it is an explore scientific refractor, i thought coma correctors were for a reflector.Do you mean a flattener?

[traveller (Bo)]

Originally Posted by vlazg

Bo, it is an explore scientific refractor, i thought coma correctors were for a reflector.Do you mean a flattener?

Should have read that in your original post...
Yes, you can try a field flattener like this http://www.bintel.com.au/Astrophotog...oductview.aspx
I use the same flattener with my ED80.
Bo

[rustigsmed (Russell)]

hi george,
i'm not too familiar with refractors it may be tilt with the camera not perfectly square to the focuser and perhaps dew on the lens?

what camera have you used, i tried to get some colour out of your image but it was very monochrome... oh hang i've just seen the 383c. i don't know perhaps something in the stacking setting you used....

Russ

[vlazg (George)]

Hi Russ,
I used nebulosity, do you use this? if so do you have a workflow?
George

[rustigsmed (Russell)]

Originally Posted by vlazg

Hi Russ,
I used nebulosity, do you use this? if so do you have a workflow?
George

Sorry George, i use DSS and then photoshop - i'm sure it is fixable though.

Btw good to see the alignment sorted