M42 first 2 exposure image

[vernmid]

Hi all,

Rather pleased with my M42 from last night. This is my first attempt at blending 2 different length exposures.  (120 seconds and 15 seconds)

Also first attempt using Arcsinh stretching

25 * 120 seconds ISO800

20 * 15 seconds ISO800

130PDS guide on an EQ5

If anyone could kindly offer some advice as to how to reduce the orangey sky at the bottom it would be much appreciated.

Many thanks

Vern

 

[wimvb]

Lovely image. What software do you use for postprocessing? From your reference to arcsinh stretching, I'd say your either using Photoshop or PixInsight. It seems to me that the red is mainly due to more noise in the red channel. You can remove it with DBE in PixInsight, or Gradient Exterminator (plugin) in PS. Running arcsinh stretch a little less aggressive, and topping it off with a curves stretch, can also reduce it.

[Bruce Leeroy]

I had a try at cleaning it up but lost alot of detail/dusty lanes.

[vernmid]

3 hours ago, wimvb said:

Lovely image. What software do you use for postprocessing? From your reference to arcsinh stretching, I'd say your either using Photoshop or PixInsight. It seems to me that the red is mainly due to more noise in the red channel. You can remove it with DBE in PixInsight, or Gradient Exterminator (plugin) in PS. Running arcsinh stretch a little less aggressive, and topping it off with a curves stretch, can also reduce it.

I used photoshop and the arcsinh  instructions generously posted here by Mark Shelly (Apologies if the name is incorrect!). I made myself and arcsinh action and have had some success with it. I did use a trial noise reduction plugin XiDenoiser and I am wondering if it somehow converted high frequency noise to something orange an blotchy! I have tried AstroFlat Pro plugin to flatten but this removes some of the detail. I think maybe a reprocess with (as you said) a less aggressive arcsinh and skipping the denoise may be interesting.

Thank you for your help. I captured my first  image of M42 (attached for comparison) when I started out on this adventure about 1 year ago. I was pleased with my results then but am even more pleased now :-) The hobby that keeps giving

 

[gorann]

Yes great start,

but regarding your background I am not sure it can be saved with processing (I played a bit with it in PS but got stuck in the noise and ended up with an image similar to that of Bruce). I think 2 min exposures at ISO800 may be a bit short to capture any of the real dust in the background and instead you have brought out chromatic noise when stretching the image. Unfortunately I think the only way to fix it would be to add more data in the form of longer exposures (5 - 10 min) to get the dust out in the background and bring the noise down. Bruce's attempt is probably close to the limit for background detail with the data you have now - but that is a pretty image on its own to enjoy while you wait for a clear sky and more data. So, you got the data needed for the brighter parts of the image but not for bringing out the faint dust so a 3 exposure image is probably the way to go now

Cheers

[vernmid]

Thanks gorann. As a matter of fact I have tried a few sneaky reprocesses of this image myself and either see both the chromatic noise AND the dimmer dust lanes or neither. So I think you must be correct. Longer exposures here we come. Hopefully have some more data soon and I will re-post. At least I now have less fear of combining different length exposure images :-) 

Cheers

Vern

[Stub Mandrel]

Keep trying with the processing.

This is a very simple tone curve where the bottom left is level up to a SHARP corner, then up to top right. Do that with the original data and it should be much better than the screen grab. Also, most of the noise is red - drop the lightness of the red channel (in hue saturation lightness) and it will improve AND increase the colour in the neb. Good data BTW.

[vernmid]

Thanks Neil. That's a good improvement. I will persevere :-)