Eta Carina - unmodded in camera noise reduction

[rcheshire (Rowland)]

For the minimalists...

Well, I had a go with an unmodded camera and long exposure noise reduction. FujiFilm X-T1.

Yep! No bias darks and flats.

165 30 second dithered frames at iso3200 - telescope ~f4.2 under a Bortle Class 6 or 7 sky.

Approximately 3 hours to get 82 minutes total time.

Aligned an stacked in Siril. Post processing in StarTools. Used the Vignetting option in Wipe in place of flats.

Difficult to balance Red and Blue - controlling the Green channel was the key, along with STs colour module magic. Still a little purple. Some strange artefacts at star edges. Laptop job, so colour not reliable - just an indication.

The conventional method of bias darks and flats would have taken around 2 - 2.5 hours plus processing time. This took the better part of 1.5 - 2 hours to convert the RAF files and process fully.

This might all look better with a modified camera. Hi res nebula

Focus on Sirius with the focus assist and red highlight which forms a ring around the star. Make the ring as small as possible.

[ChrisV (Chris)]

Nice shot Rowland!

You've got a pile of red there. As good as others I've seen with modded cameras. The vignetting option looks like it did the job.

[xelasnave]

Very nice work and thanks for the useful hints.
Alex

[raymo]

The red is strong in Eta, so it also makes an acceptable single exposure
image.
raymo

[rcheshire (Rowland)]

The attached PDF shows different processing techniques for unmodified camera RAW images - won't work for jpeg.

The dcraw commands are there for anyone who wants to give it a go.

Basically, convert raw to colour images first and then align and stack. If you have ufraw or something similar and not too many files the process can be done manually with a GUI.