Orion - 1st Attempt - Advice Needed

[agthomson]

Hi all! I managed to finally get a photo of M42 Orion. Based on where I live, and the surrounding buildings this is an incredibly difficult targte for me to get. I literally need the stars to align in terms of day job, the moon, the direction of the wind (chimney smoke) not to mention cloudy skies or poor sky quality.

This is a combination of 43 x 120s exposures and 115 x 60s exposures for a total of around 3hrs 20mins, taken through an Optolong l-Enhance Duo (dropped my LP filter), stacked in DSS, and processed very lightly in PhotoShop (balanced levels, slight curve change, increase vibrance and saturation).

I suppose my question is I have another opportunity this evening to add more data. What would be more useful - longer exposures for feint detail, or shorter exposures to tame the core? The 120s exposures completely blow out the centre of M42, but are useful for picking up the feinter nebulosity. I was thinking of adding in some 300s exposures to really bring out the feinter details, but offsetting that with a bunch of 30s exposures to try and bring down the core.

[geeklee]

1 hour ago, agthomson said:

but offsetting that with a bunch of 30s exposures to try and bring down the core.

That's looking great and I understand the frustration of catching this through a variety of obstacles - the chimney one rang true as something I only noticed myself recently looking out to the S/SW here!  

Shorter exposures on the core is a good idea and won't take long to get the needed subs as there's so much signal there.  You won't need to spend hours on it.

I see you gave yourself some headroom in the image above as it has all this Ha and dust in the background

Good luck tonight.

Edited January 19, 2023 by geeklee

[Elp]

I would drop the lenhance. It's such a bright target that even 5-10 sec reveals most of the main central area. For the centre you want to take around the same time exposure (maybe up to 5s, it depends how fast your optics are) otherwise it's too bright. You'll find you'll probably get much more details without the filter. Its a fantastic first attempt.

Edited January 19, 2023 by Elp

[teoria_del_big_bang]

Nice 1st attempt, far better than mine that's for sure.
The only way I tamed the core was to use  short exposures and longer exposures then blend the core which was cut from the short exposures over the main image using the longer exposures done in Photoshop, although that is not my main processing software so had to just follow a tutorial I found on line. I am not sure what sort of exposure times I used, i think pretty short for the core, i will look see if i can find the info.

Steve

[teoria_del_big_bang]

Ah found it, not one of my best images actually now I look back, done in my early days and I think the seeing was not great as only managed 2 frames at 240 sec of R,G and B and 2 frames at 60 seconds of RGB for the core and I think 60 S was far too much for the core so 30 seconds probably better.
If you use THIS blending technique then probably don't need very long exposures for the rest as you will be able to stretch that more without affecting the core.

 

For what it is worth my meagre image:
https://stargazerslounge.com/topic/347340-first-attempt-at-combining-different-exposures-another-m42/#comment-3776318

Steve

[agthomson]

Thanks all for the suggestions.

Yes, I gave myself plenty of headroom in the stretch as I didn't want to bring out too much Ha. While the Optolong filter is great for most of the targets I like to photograph it ruins several others!

I much prefer your colours Steve, so that's something for me to work towards. Once I replace the broken LP filter (I really need one when pointing South) i'll give M42 another go. Next step for me is to move into mono + LRGB and narrowband, as that side of AP interests me much more.

I took 120 x 10s exposures (so 20mins) and 10 x 300s exposures (bringing the total to 4 hrs 30mins) so that I have a range of data to play with. From a quick stack I can definitely get the core to be less blown out with just the 10s exposures. Need to actually brush up on my processing skills beyond a quick stretch and levels balance and actually work with the RGB channels prior to combining into a colour image. That belnding technique looks interesting, so will give it a proper read later as well.

[sinbad40]

Cracking pic.

Same target i am after, I was trying to get some myself last night, by the time i got setup, the cloud cover had arrived again, fingers crossed for tonight.  After the longer exposure for mine.

Decided when i came back to astronomy 6 months ago, that i wanted to spend time on each object and not jump around each night like i used to (10+ years ago).

[agthomson]

3 hours ago, sinbad40 said:

Cracking pic.

Same target i am after, I was trying to get some myself last night, by the time i got setup, the cloud cover had arrived again, fingers crossed for tonight.  After the longer exposure for mine.

Decided when i came back to astronomy 6 months ago, that i wanted to spend time on each object and not jump around each night like i used to (10+ years ago).

Last night was touch and go for me. The right hand side of my capture has lost about 5% due to cloud cover but I can crop and work with it.

I took a break from AP for a while mostly due to time constraints, but also because i've "seen" the objects I want to with my current setup and would need decent investment to get a better view of the smaller DSOs. Believe it or not, but the Vaonis Vespera actually got me back into astrophotography. No, I didn't buy one, but I had one in my basket. I decided to run through my usual AP set-up process to actually see how long it took me to set up and get imaging compared to the 10 minute claim of the Vespera. I had it in my head it was around 1hr30mins to cart all of my kit outside, plug it all in, polar align and run some test exposures on my target. The Vespera interested me as it took nearly all of that time away, leaving me with my favourite part which is planning my acquisitions and working with the collected data.

I used to bounce around from target to target every clear night, but i've "seen" most of the targets I can from my garden, so i've decided to actually put effort into each one from now on. While my 1hr30mins was slughtly over-estimated for the 1st setup time, night 2 and 3 on Orion I was collecting data within 30mins. Most of that time was getting the equipment set up in my garden and testing the exposure time.

What I need to do now is just collect more data at my preferred exposure time, instead of having to work with 3 or 4 different exposures!

[rickwayne]

Exactly right. If you're not blowing out the highlights, enough integration time will let you resurrect really, really dim areas without changing the exposure time. If you think about it, even if you're only capturing 1 photon every 3 exposures from a given pixel's area, that still adds into the stack.

The benefit of longer exposures is less read noise, since you're getting the same integration with fewer reads. Downside is degraded outlier elimination (e.g. satellites).

Orion is one of the few targets in the night sky that is so bright that it does respond well to HDR techniques. You don't need nearly as much integration time for your highlights (i.e., the Trapezium) because highlights will be less affected by noise to begin with. I use the poor man's Photoshop HDR of simply putting the highlight image on top, giving it a layer mask set to black, and painting a gentle bit of white on the Trapezium with a 0% hardness brush set to pretty low opacity. If I'm impatient it looks like someone burned a hole in the image, if I'm not it's undetectable.