m42 M42

[Maxrayne]

Messier 42

I know Orion has been done to death but atm it's one that's within my meagre reach. Was thinking of reshooting this at 200mm to get the slightly longer exposure times and maybe drop the ISO to stop the core blowing out so much? Obviously more captures, getting out of the city and waiting until it's higher would help 

Nikon D5300
360 image stack, 10 offsets, (oops on the darks)
300mm @ 1.6 seconds exposures
ISO 5000 @ f / 5.6
Stacked in DSS, data stretched out In LightRoom and Photoshop. Lots of noise in this as it was very low down on the horizon and I forgot to add the darks, but still my best attempt yet. The core and several brighter stars are blown but I've sacrificed those for the sake of cloud detail

[Galen Gilmore]

Looks pretty good despite the lack of darks. If I were you I reset the curve stretch, and create a more gentle slope. You are introducing way too much noise and background color trying to pull out detail. Thats just nitpicking though, it's a very nice image even with a lack of dark frames.

[Galen Gilmore]

I hope you don't mind me posting a reprocess of your image.

This is what happens when you decrease exposure, increase contrast, do a color correction to get rid of the green background, and slightly soften the image to remove some of the noise.

So you can see your image has a lot of potential.

[Maxrayne]

Oooooo I like, ty kindly ?

I'll go back and have a revisit once I get my 6 year old off of me ??

[cjdawson]

Well done on your M42 image.   That looks great.

The don't worry about blowing out the core, it has to be done to get the faint detail.    The trick is to take a series of shots exposed for the core only.  This way, you can mask the blown out core with the non-blown out version to be able to get the trapezium into the image.

 

[Maxrayne]

Thank you ? Is that when layering in PS comes into play? I'll be honest, I've never attempted that one yet, although I guess I'll have to at some point. Assuming I'm going to get clear (ish) skies sometime soon I'm planning on a reshoot.

I'm still having a play with the image atm and I've managed to get more out of that area to the lower left and a hint of red above the main part. But I think that's the absolute limit with the data I have.

If anyone wants to have a go at it the file link is below (assuming I've set the permissions right)

 

https://1drv.ms/i/s!AiwnMLNod1FKhbVBU4NmENFYlsPVAQ

[alacant]

Hi. Well done. You could take some flat frames too. This would help even the stack, particularly around the corners. Bias frames are also easy to add and may help with the noise. HTH.

[Maxrayne]

I've got a couple of sets of darks from a different night, same ISO just different exposures, would they be any use?

[alacant]

6 minutes ago, Maxrayne said:

same ISO just different exposures, would they be any use

Hi. No. The dark frames must be at the same temperature, same exposure and ISO as the light frames. The flat frames can be any temperature but must have identical optical trains as the flat frames. Bias frames are simply taken in the dark with the shortest exposure your camera can manage. HTH.

[Maxrayne]

Ah, that's what I thought, but just thought I'd ask anyway if there was a way round it. From what I've read about flats, they're a bit of a pain in the posterior to get right?

[alacant]

1 hour ago, Maxrayne said:

just thought I'd ask anyway if there was a way round it

Hi. With my Canon 700d, YMMV: The only free lunch I know in this game is that you can lose the dark frames if you can dither between the light frames. A median or Kappa stack will then make a particularly noise free image. Light, flat, bias with dither; yes. Lose the dark frames. Should work just as well with your Nikon I think. HTH.

[cjdawson]

15 hours ago, Maxrayne said:

Thank you ? Is that when layering in PS comes into play? I'll be honest, I've never attempted that one yet, although I guess I'll have to at some point. Assuming I'm going to get clear (ish) skies sometime soon I'm planning on a reshoot.

I'm still having a play with the image atm and I've managed to get more out of that area to the lower left and a hint of red above the main part. But I think that's the absolute limit with the data I have.

If anyone wants to have a go at it the file link is below (assuming I've set the permissions right)

 

https://1drv.ms/i/s!AiwnMLNod1FKhbVBU4NmENFYlsPVAQ

That’s one time when they are useful.   There’s a whole bunch of othe techniques that you can do too, so it’s worth spending time learning about it

[Filroden]

19 hours ago, Maxrayne said:

I know Orion has been done to death but atm it's one that's within my meagre reach. Was thinking of reshooting this at 200mm to get the slightly longer exposure times and maybe drop the ISO to stop the core blowing out so much? Obviously more captures, getting out of the city and waiting until it's higher would help 

I think many of us cut (lost) our teeth on M42. It looks like an easy target to try first as it is so bright. But that brightness makes it one of the hardest to capture. It has such a massive dynamic range from core to outer edges that it's one of the few (only?) target where capturing images at different exposures and blending with a HDR process makes a huge difference. An alternative is to make a copy of the original and develop both images to retain maximum contrast in different areas - one for the brightest regions and one for the faintest details then blend the two together with layers so you bring through the best of both.

I'd recommend a few things for you:

• Your colour balance looks good but you have a nasty light gradient coming from below the target. I'd guess this is light pollution? Don't be tempted to try and balance the colour with the gradient left in the image. Reducing green in the image will make it too blue. You do need to think about some way to remove the gradient. PS has an add on (Gradient Xterminator) that can do this.
• If you're at your fastest f-stop on the lens, think about stopping it down one or two. This might help you will the star shapes. It does mean needing longer exposures but the image will be easier to stack with more defined stars.
• You can lower your ISO. I don't know how the Nikon's perform, but for a Canon, ISO800 to ISO1600 tends to optimise noise. Just be careful on exposure time not to get star trails.
• Some of your stars have square blocks around them that look like they have been desaturated. Have you applied a square tool to remove any chromatic aberration? You may want to use a feathered round tool and use a blend option so you cannot see the artefacts left by the tool.

[Maxrayne]

Thank you kindly. I've got a few days off now so I should have time to go back and have another look ?