California Nebula Re-Shoot

[MarkS]

This is the data I shot on the last imaging night: Sat 3 Dec.

440x30sec at ISO 10000 using H-alpha modified Sony A7S on Tak Epsilon 180ED giving 3hours 40minutes total exposure.



It's a smoother result than the previous proof of concept: http://forum.orpington-astronomy.org.uk/index.php?topic=10871.0

I'm now in the swing of using my updated processing sequence:  PixInsight Drizzled stacking followed by Photoshop CC for removing residual gradients in the linear stack (performed in 32bit mode).  Asinh single stretch in IRIS to maintain colour accuracy from the very dimmest to the very brightest objects.  Photoshop CC ACR Filter for the final noise reduction.

I experimented with a stronger asinh stretch to bring out the dust more but it detracted from the emission nebulosity.

Full size version is here:
http://www.markshelley.co.uk/Astronomy/2017/california20161203.jpg

Mark

[JohnP]

Very smooth - like the process. John

[Carole]

Great improvement Mark, I like the colour better in this process.  You are bringing out dust in most of your images these days that is not usually seen on the average image of the same data.  Very impressive combination your scope and the A7S.  Not to mention your post-processing skills.

But puzzled about the drizzle stacking - never used it, but I thought drizzle was used to to stack only part of an image, have I got this wrong, or does it have a different meaning in Pixinsight? 

Carole

[MarkS]

Drizzle is drizzle.  It should ideally be done to the whole image.  I often see recommendations to do it on part of an image but that is because drizzle done by DSS often blows up its memory limits.  Bayer drizzle in PI works flawlessly and really tightens up sharp details in DSLR images, giving them the resolution usually only seen from mono cameras.

Mark