Quest to image the Orion Nebula - part two

[Robp]

So about a year ago I started my 'quest' to image the Orion Nebula thread I have decided to pick this up again this year. 

The original thread is here - http://stargazerslounge.com/topic/228487-my-quest-to-image-the-orion-nebula/

My aim is to show how my image of M42 can improve with practice, experience and investment in upgrading gear. 

As this is a work in progress thread I've posted this in the main imaging section; If a mod feels there is a more appropriate place please move it.

Since the last thread I have made one major addition to my gear, I will now be imaging with a WO Star 71 instead of my 130pds.

The main benefit of using this will be that I no longer have to do a mosaic to fit everything in. 

My last attempt was done with 900 second subs, but this time I will be starting fresh and upping this to 1200s. I'm aiming for 30 HA and OIII subs and then see how I go.

It was clear last night (the first time in a while) and I managed to get some data to start me off. 

Due to the layout of the houses and a street light, I can only get a couple of hours each clear night to image this target. 

I have done a quick process to see how its going, currently stands at 6x1200s and 30x30s for the core:

The Gear list is:

HEQ5

WO Star 71

Atik 314L+ Mono

QHY5L-IIc as the guide camera

Hopefully a few of you will join me for this thread as I build upon this image and offer your guidance along the way.

[ecuador]

It would have been more exciting if you had not started with a rather decent Orion image like I see in your first post of the other thread

Yes, the difference in detail is still immense of course! Carry on sir!

[MarsG76]

That is a beautiful image of M42... definitely a major improvement over last year.. well done.. looking forward to see your bi-color version.

[red dwalf]

nothing wrong with that, and you have controlled the core nicely.

[ollypenrice]

That's going very well but the core is still a bit over exposed and the transition between long and short could be smoother. How does the core set look before stretching? If it's possible to see the Trapezium stars and the Fish Mouth is reasonably dark then it will be fine. You just need to stretch it carefully to resolve the Trap region.

For me the best method of combining long and short subs, by far, is this one. http://www.astropix.com/HTML/J_DIGIT/LAYMASK.HTM

There have been some changes to Ps since then but once you have the two datasets and the layer mask in place you can go to Window-Arrange-New Window For...

This is going to be a cracker I think.

Olly

[Robp]

Thanks for the nice comments all.

Olly:

For the 30s core set I can see the Trapezium stars (I had to look up what the fish mouth was ). I'll have to wait until I'm home and have a more detailed look but I think I have just overdone a stretch at some point. I might test different lengths of shorter subs to see which length will be the best fit.

That was the guide I used but I couldn't work out the preview so I just made a guestimate on the settings. Spending a bit more time on the processing should improve things.

Where you mention the transition between the short and long exposures being smoother is there anything in particular I should be keeping my eye open for?

[Robp]

So I managed to grab some OIII data during a brief clear spell with no moon.

It isn't the best quality but will have to do until I get something better.

I have done a quick comparison of the 30 second core shots, 30x30s of both HA and OIII

No stretching applied to HA, a small linear stretch applied to the OIII.

I'm going to have to stretch them as they are smaller than the overexposed areas on my longer exposures.

The next time I get a clear sky I'll take a few different  short exposure times to compare results.

When is the best time to integrate the core images to the main image, before stretching the main image or when I am finished?

[Robp]

Hard to believe that its a month ago since I managed to get some clear skies around here.

Last night I got a lucky break so gathered some more OIII. I have done another  quick process to see how its going.

So far it consists of HA 6x1200 and OIII 14x1200

The OIII might have a bit of streetlight incursion in the top right, will have to gather some more HA and see.

[Robp]

I got some clear skies last Friday so have managed to add another 10x1200s to the HA total.

I have had another quick process to see how its going.

Neither image has had any noise reduction, star control or sharpening applied.

I'm pretty happy with the noise level so far, I didn't push the OIII very hard in this one as anything out towards the edges is either lost in the glow from a street light or lost in noise

I'm going to continue adding HA when the next opportunity arises to see If I can pull out some of the fainter stuff on the edges out from the noise. I'll only grab some additional OIII if I get a rare moonless night.

[ollypenrice]

Very exciting!

Regarding stretching, you don't always have to shoot shorter subs because, whatever you can see in the unstretched data can, with the right proeocessing, be made visible in the final image. It's perfectly possible, therefore, to use the linear Trapezium data as if it were ultra-short sub data and blend it with a stretched version of itself using the Layer masking technique. I do this very often, which is why I frequently argue that there is no need for short subs other than on very unusual targets such as this one.

Anyway you've found your way into the Trapezium very nicely in the later images.

One thing about blending in very bright parts of an image is that they often lack colour saturation. The brighter a stretch the less intense less intense becomes its colour, so boosting the saturation of the bright layer can help make it blend smoothly.

Olly

[Robp]

On 25/01/2016 at 10:17, ollypenrice said:

Very exciting!

Regarding stretching, you don't always have to shoot shorter subs because, whatever you can see in the unstretched data can, with the right proeocessing, be made visible in the final image. It's perfectly possible, therefore, to use the linear Trapezium data as if it were ultra-short sub data and blend it with a stretched version of itself using the Layer masking technique. I do this very often, which is why I frequently argue that there is no need for short subs other than on very unusual targets such as this one.

Anyway you've found your way into the Trapezium very nicely in the later images.

One thing about blending in very bright parts of an image is that they often lack colour saturation. The brighter a stretch the less intense less intense becomes its colour, so boosting the saturation of the bright layer can help make it blend smoothly.

Olly

Thanks Olly.

I think I'm improving with each process, still have a long way to go though . The biggest improvement I have made this year was learning to slow down and take my time with each step and the ever growing collection of 'Olly processing tips'

I haven't had any clear skies since the last update so no new data to add yet.

I have however made a new purchase of a second hand Atik 414ex.  
I think the chip size and pixel size is pretty much identical to the 314L+ so should be relatively easy to combine the data.
Would it be best to stack the two different camera subs separately and combine in Photoshop or should I just throw it all in to DSS?

Another thing I was contemplating was taking some LRGB data.
I have the filters to do this but with the Light pollution I have its not something that I have actively done.
I'm assuming there is a background ADU value that I wouldn't want to go above and with the light pollution the subs would be relatively short compared to the narrow band. Would it be worthwhile exploring this option and combining with the narrow band?

 

[Robp]

So I have had a couple of clear nights the last week and I was on holiday from work as well (lucky me).

The moon wasn't best placed but I managed to grab a load of data with my new camera.

I stacked all the exposures from both cameras in DSS and the result was fine so I gave it another quick process.

For HA I have 36x1200s exposures so a total exposure time of twelve hours. I'm really happy with how this is progressing.

I might add some more HA if I get a chance but I'm really hoping I get a clear night with no moon, so I can get a bit more OIII before this target moves on for another year.

Thanks for looking.

 

[Stub Mandrel]

On 25/01/2016 at 10:17, ollypenrice said:

Very exciting!

Regarding stretching, you don't always have to shoot shorter subs because, whatever you can see in the unstretched data can, with the right proeocessing, be made visible in the final image. It's perfectly possible, therefore, to use the linear Trapezium data as if it were ultra-short sub data and blend it with a stretched version of itself using the Layer masking technique. I do this very often, which is why I frequently argue that there is no need for short subs other than on very unusual targets such as this one.

Anyway you've found your way into the Trapezium very nicely in the later images.

One thing about blending in very bright parts of an image is that they often lack colour saturation. The brighter a stretch the less intense less intense becomes its colour, so boosting the saturation of the bright layer can help make it blend smoothly.

Olly

That made me go back and look at my short subs of M42. Even 2 seconds at ISO1600 burnt out the trapezium into one glowing lump. Not a patch on Rob's images :-(

I will try Iso 400 and sub 1-second exposures next time.

[ollypenrice]

2 hours ago, Stub Mandrel said:

That made me go back and look at my short subs of M42. Even 2 seconds at ISO1600 burnt out the trapezium into one glowing lump. Not a patch on Rob's images :-(

I will try Iso 400 and sub 1-second exposures next time.

Lack of well depth on the DSLR I guess? My thumping great Kodak chips may lack resolution but not well depth.

Olly

[Robp]

5 hours ago, Stub Mandrel said:

That made me go back and look at my short subs of M42. Even 2 seconds at ISO1600 burnt out the trapezium into one glowing lump. Not a patch on Rob's images :-(

I will try Iso 400 and sub 1-second exposures next time.

I haven't shot M42 with a DSLR but I'd say drop the ISO all the way down and start from a low exposure and work your way up (or down) to know the limits.

The good thing about short exposures is they don't take long to gather