M42

[The Thing]

I am a bit mystified by the flatness of the Ha on the right of the picture.

137x60s 2h17m Gain120 Offset 4 Temp-5C 10xDark, 10xFlat, 10xDarkFlat Processed in PixInsight using Weighted Batch Pre-Processing v2 (as easy as DSS!) and EZProcessing scripts with a tweak using Curves Transformation.

Image date, time and location:   2021-02-10, 20:22-00:17, Manche, France
Telescope aperture and focal ratio:   Sharpstar 61EDPH F4
Camera and filters used:   ZWO ASI294 MC Pro, Optolong L-eNhance Ha, Hb, OIII filter
Processing applied:   PixInsight (WBPP2, EZ, CT)

[Carole]

That's come our really well Duncan.

Very nicely processed except I think the brighter part of the nebula is a bit bright and obscuring detail, did you take any shorter subs to combine?

I am a bit mystified by the flatness of the Ha on the right of the picture.

As regards your comment above, I had a feeling that Ha was a bit lacking on that side of the nebula and did a search and found this one below.  Whilst there is Ha on that side, it's no-where near as bold and detailed as on the left side.

https://www.astrobin.com/340230/?nc=user

Carole

[The Thing]

Thanks Carole. Noted about the Ha.

I used a PI function called Masked Stretch, probably need to ratchet it up. The well depth of my asi294 and so it's dynamic range means at 60s I can see the trapezium stars on my main pc. I think conversion to jpeg has lessened the range somewhat, 32 to 8 bit🙁

[RobertM]

Nice one Duncan and very pleasing colours, pretty good stars in all four corners - I presume this is using the reducer ?

Are you autofocusing yet or is this with a Baht ?

JPEGs are always a PITA when it come to dynamic range.

Robert

[The Thing]

Thanks Robert. I'm using PhotometricColourCalibration in narrowband mode with the passbands entered.

It is using to the flattener which makes it a 5 element apo. The focus is automatic but I think I need to tighten the grub screws and glue them as it's gone sloppy! The autofocus often fails but it's pretty  good anyway. More tweaking.

[Roberto]

That's a cracking shot Duncan.  I love the nebulosity and framing.

Roberto

[The Thing]

Thanks Roberto, high praise much appreciated.