M42 beginners question - Trapezium

[Peter_D]

Hi,

Sorry, another M42 question 🙂

I captured M42 for the first time a couple of nights ago and used Deep Sky Stacker and Gimp on the images.

My question: is there a way to retain seeing the Trapezium and seeing more of the surrounding gas / dust? At the moment, if I stretch the diagonal line in Gimp (sorry, can't remember the exact setting) , I get more visible gas but the centre of the nebula then comes overblown and white.

Any suggestions? ISO setting too low?

Many thanks for any feedback!

PS Yes, the stars are not great in my image, I know. Polar alignment seemed fine but my GP uses the Skywatcher upgrade motors that run on batteries - probably should have replaced them before imaging.

 

Image: 29 x 20sec lights; 10 x 20sec darks

ISO: 800

C6 OTA; un-modded Canon Eos 60D. Vixen GP-E Mount with SW EQ5 Motor upgrade (unguided)

[teoria_del_big_bang]

I know it can be done in PhotoShop using layers but never used Gimp. So definitely can be done just needs someone is is proficient with Gimp.

Steve

[smashing]

Great effort!

I believe a lot of people take two sets of exposures (one long and one short) and then blend them together in PS so that the core in the long exposure images is effectively replaced with the core of the short exposure image...if that makes sense.

[Chefgage]

Using layers and masks in GIMP you basically select the middle area so that when you do your levels and curves it affects the image but not the selected centre region.

[Jamgood]

The first practice run I did of M42 had an overblown core but I was mainly just checking framing and exposure. The second time I took a series of images and got this.

12 x 300s - 12 x 30s - 12 x 10s Lights

12 x Darks for each set of Lights

30 x Bias

30 x Flats

 

 

Not perfect and needs some more data when I can but I'm happy with it so far.

 

I didn't use any layers or anything. Just stacked in DSS in groups and edited the final image in Photoshop. 

[Nik271]

As people have already said there are basically 2 ways:

1.Take multiple pairs of exposures, one of the outer nebula and one for the trapezium and stack them separately. Then you can merge the two images in GIMP and play with masks and blending ratios.

or, if you just have one image

2. You can actually freely draw a region in GIMP around the core, select it and edit it separately from the rest.

2) is the more lazy way but for better results I would suggest you use 1). 1) is also the way to process narrowband images using filters which is likely to get the best results. 

 

[Peter_D]

Thanks for the pointers and suggestions!

Much appreciated

Peter

[Peter_D]

1 hour ago, Jamgood said:

The first practice run I did of M42 had an overblown core but I was mainly just checking framing and exposure. The second time I took a series of images and got this.

12 x 300s - 12 x 30s - 12 x 10s Lights

12 x Darks for each set of Lights

30 x Bias

30 x Flats

 

 

Not perfect and needs some more data when I can but I'm happy with it so far.

 

I didn't use any layers or anything. Just stacked in DSS in groups and edited the final image in Photoshop. 

That's a terrific image! What's your setup? 

[Jamgood]

19 minutes ago, Peter_D said:

That's a terrific image! What's your setup? 

Cheers. 👍

I'm using a Skywatcher 130PDS on a HEQ5. Camera is a Canon 60Da with Astronomik CLS filter and Baader MPCC.

Guiding with Orion 50mm Scope and Orion Starshoot camera.

Nothing amazing but I'm very much a newbie, learning as I go. 

[Nerf_Caching]

Here is how I ensure the core is not blown out in GIMP. I've illustrated it here with 6 screenshots:

1. Here I have a photo with the core overexposed. 

2. This is a layer I've made prior to the top one with a less 'stretched' version showing the core nicely(the bottom layer is just my unstretched photo. I will not worry about that.).

3. Move the less stretched layer in 2. up to the top.

4. Click Layer>Mask>Add Layer Mask. Select 'Black(full transparency)'. After selecting, it should reveal the overexposed layer underneath. Make sure that layer is toggled.

5. There should be a black thumbnail beside the thumbnail of your top layer. Make sure you are working on that black thumbnail.

6. Click paintbrush with the settings shown on the left. Make sure foreground and background colors are white and black respectively(Shown above paintbrush settings). Now color in the core to reveal detail. Double click on the top layer and click 'New from visible' after you're done.

Hope this helps. Cheers!

 

Edited January 3, 2021 by Nerf_Caching

[Peter_D]

Thank you very much Nerf_Caching!