Astrophotography with Digital Camer -Orion Nebula (M42)

[James G]

I posted on this about this time last year, but following another thread posted by Steve (botty1963) today, I thought an update with a bit more detail would be in order .....

I finally got a few hours of clear sky last night with Orion at about max altitude. Plus the temp had dropped to about zero with minimum breeze. So tried for the Orion Nebula (M42).

For those who are not into astronomy or astrophotography, the nebula is around the middle stars in the sword and is really only visible as a fuzzy area when viewed in binoculars.

My setup was a tripod mounted Canon 7DMk2 with cable release and with a Sigma 50-500mm telephoto extended to 500mm.

Capture settings:- a sequence of 20 images using a Bulb setting , 1 sec exposure with 5 secs mirror lockup between each capture, all at F5.6, and ISO 5000. (Focus rather obviously was infinity, but my tip is to use the peripheral areas of the focus screen to best assess the sharpness of stars in the viewfinder.)

I also shot a dark frame (ie using exactly the same settings as for the nebula & stars, but with the lens cap on. This is used when processing the images)

(I also shot sequences at ISO3200 and ISO1600, but ISO 5000 gave the ‘best’ out of camera captures)

To process the images I used Photoshop CS6 .

In ACR
1) I identified the ‘best’ capture in the sequence and the pre-processed it in ACR to get the most detail from the image. No sharpening was applied, but I did reduce obvious noise.
2) I then synchronised the process settings from the first image across all the captures, including the dark frame.
3) All images were then saved and opened in Photoshop as a layer stack.
In Photoshop
4) Once opened as a layer stack, the dark frame was copied and placed in the stack so that each image had a corresponding dark frame associated with it, forming a layer pair.
5) Each image/dark frame pair was then processed , changing the blend of the dark frame to ‘Subtract’ and then merging the pair back to a single layer. (You can use a ‘ Ddifference’ blending mode as an alternative.) The purpose of this step is to remove ‘latent’ background signal from the captured image which can be a significant element of this type of capture. Purists would argue that this is not strictly a dark frame subtraction, since it should be applied to the raw capture, but it works for me!
6) Once the dark frame adjustments have been applied, I then adjusted the opacity of the stacked layers from the bottom up, setting each layers’s opacity according to the following sequence (This is a final noise reduction process for the ,stacked images.) 100%,50%,33%,25%,20%,17%,14%,12%,11%,10%,9%,8%,8%, 7%,7%,6%,6%,6%,5%,5%
7) Finally I created a merge layer of the underlying stack. (Once this is done the underlying stack can be deleted to reduce the overall file size.)

General post processing
Having generated the merged stack layer from the last step, I processed for levels, vibrance, hue and saturation, and final image sharpening .

#1 ISO 5000 image


#2 ISO 3200 Image


Hope this helps out there

C&C welcome

[mastamak]

Thanks for posting that explanation, James. You have obviously done a lot of hard work on that image. I am keen to give it a try.
Grant

[rpcrowe]

Nothing like blundering in to an area in which I know nothing about. I don'e even know what this time of image should look like.

However, nothing ventured, nothing gained. I copied the ISO 5000 image and opened it in CS6 and then used my NIK Viveza Plug In to work with it. I increased the structure and decreased the shadow adjustments. This is what it finally looked like.

[James G]

If you call that blundering! Very nice!

[James G]

I've gone back and added to a thread I started back in 2016.
I was going to start a new thread but for reasons that are not yet undersdtood, I cannot initiate new threads , only add posts to existing.

Since January 2016 I've been working away at improving my astrophotography. Last autumn I finally bit the bullet and attached my EOS M5 mirrorless camera to my 4" refractor.
For the present, since I am more interested in medium field captures I have not considered eyepiece projection, but simply used the 1000mm telescope tube as a prime lens for the camera. (i.e. I substituted a traditional SLR telephoto for my telescope.)

The images below of the Orion Nebula and its companion, the Running Man Nebula are the culmination of this winter's efforts.

The camera was attached a Vixin 4" reftractor with a focal length of 1000mm, on a tracking equatorial mount.
The processed images are the result of 604 individual captures, (68 at 2 seconds, 356 at 3.2 seconds, 180 at 5 seconds). Additional dark and bias frames were also created at each of the exposure times. The ISO was camera max of 25600.

The source images were stacked and pre-processed using DeepSkyStacker (freeware) and for comparison , an evaluation copy of a new software, AstroPixelProcessor.

I'm very familiar with DSS,but have been very impressed with APP and will probably invest in a perpetual licence since it has a lot of 'statistical' functionality, not available to DSS. (Particularly Background calibration and Light Pollution removal tools).

The final PP and 'artistic' interpretation in presenting each image is Adobe CC.

Looking back at my early efforts in 2016, I'm definitely making progress. But, being absolutely honest, although interested in astronomy since childhood, my astrophotography aspirations are photography related rather than any attempt at scientific exactitude.





There are more images, different renderings of the same stack, at the following link:-
https://drive.google.com/drive/folders/1heTzm6CvZW2HyslsL9f8JhxD6cOLMpvV?usp=sharing

Using a more conventional DSLR & telephoto setup, here also, are a couple of Moon shots from the last few weeks.....





All C&C welcome

[Shadowman]

Nice set.

[Manfred M]

I was going to start a new thread but for reasons that are not yet undersdtood, I cannot initiate new threads , only add posts to existing.

Very strange - how are you trying (unsuccessfully) to create a new thread? Is this an intermittent issue or does it occur every time you try to create a new one? How long has this been going on?

[James G]

I had mailed Dave about it. Not sure what is happening. It's not intermittent, happens whenever I try to start a new thread. Been happening for a couple of weeks!

I get a error message when trying to post a new thread that :-

Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 15162163 bytes) in /home/cic/public_html/forums/includes/class_bbcode.php on line 861

I assumed might might be local to my machine(s) and removed Firefox and reloaded, but the problem persists.

Been too busy on other things this last week or so, so have not followed it further yet.

I was posting the astro shots for family members earlier today (emailing them) and took a notion to post on CiCs too, so added to an old thread I'd already posted.

Was going to follow up on the error message later.....

It is definitely strange since I switched to a different browser and it persists, ....which suggests it is at the CiCs end of things?

[Manfred M]

I had mailed Dave about it. Not sure what is happening. I get a error message when trying to post a new thread that :-


Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 15162163 bytes) in /home/cic/public_html/forums/includes/class_bbcode.php on line 861

I assumed might might be local to my machine(s) and removed Firefox and reloaded, but the problem persists.

Been too busy on other things this last week or so, so have not followed it further yet.

I was posting the astro shots for family members earlier today (emailing them) and took a notion to post on CiCs too, so added to an old thread I'd already posted.

Was going to follow up on the error message later.....

It is definitely strange since I switched to a different browser and it persists, ....which suggests it is at the CiCs end of things?

That looks like a server side issue at the CiC host error message. As I have not had any posting issues, I suspect it must have been resolved.

[James G]

That looks like a server side issue at the CiC host error message. As I have not had any posting issues, I suspect it must have been resolved.

No, it is happenning to me right now!

[rudi]

Very nice images James,

Comparing images in your OP and post nr 5, you certainly made a strong progress.

I was a bit surprised about your very high iso setting. I usually use an iso off 1600-3200 on my 50D, but that is off course an old camera.....

Allow me to add two things (M42 post nr5):
1°: I can not see the Running Man, because I think he is not in the current picture. Just a remark nothing else...
2°: Something I struggled with myself also, is the core off M42, which consist off 4 very bright stars, and very easy to blow out. Iff I remember me correctly, something in the range off 1sec iso 1600 will bring you in the range to 'catch' the core nicely... , to blend in in post.

[James G]

Rudi thanks... you are of course quite correct, I was getting a bit ahead of myself. The Running man nebula is out of frame on these shots. I have a portrait sequence which show both nebulae which I am still processing.

As regards capturing the stars in the core I agree, I need to re-shoot at a lower ISO . ( I do have a couple of sessions at lower ISO (6400) from a few months back but the conditions were not so good, with slight high altitude haze, so I'm hoping to reshott and then hopefully blend the images produced.

My real challenge is that I live in a severely light polluted area (Birmingham UK) and am within 3 miles of Birmingham International Airport, so I'm actually surprised quite a lot by the image quality I'm getting.

Raising the ISO, combined with increasing the number of captures, and varying the exposure times has been something of an experiment to try and counter the light pollution issues.

I mentioned AstroPixelProcessor in the post, it seems to have a particularly effective set of functions to remove/minimise light pollution which I'm still learning about. My somewhat inexperienced opinion is that it is considerably better than DeepSkyStacker. Processing time for APP is considerably longer than with DSS though.

Later this month I will be visiting family in Ireland and they have really good 'dark skies' compared to Birmingham so I'm hoping for clear skies. I live in hope ....

[rudi]

Living in a severely light polluted area is indeed a real challenge. Though I think our area is not so 'bad' as yours, I use a CLS clip in filter to cut down the light pollution.

Till now I used DSS, but I will look into AstroPixelProcessor.

Awaiting with great interest for your next pictures....

Wish you 'clear skies'.

[JBW]

I'm with you James beauty over science. Your skies are more cooperative and your skill set much further along. I can only hope for clearish skies.

[James G]

Thanks Brian

Your skies are more cooperative

Definitely not so! I've been waiting 3 months to get sufficiently clear skies to try out the new setup. Last half of January proved to be the most productive. The UK, especially the Midlands can be persistently damp, foggy and generally, rather dank

Having spent my working life as a chemist and biochemist, working on environmental improvement projects and then latterly in IT (Information Science), I'm enjoying throwing off constraints and indulging in more creative pursuits.
What is interesting is that I have been rediscovering childhood and adolescent interests which were 'put aside' as the practical aspects of career aspirations took priority.