#1  
Old 01-01-2019, 08:49 PM
assbutt94
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C92 Carina Nebula

I took some test shots of C92 after I was finished shooting M42 the other night and decided to process them for some practice. Only a dozen or so subs stacked, im focusing on capturing m42 at the moment. I had to down-sample it to get it to upload.

The stars look terrible towards the edges, Im not at ideal backfocus distances and I think this might be causing this. I think this same problem is causing the bright double star Hatysa to cast a large offset halo flaring into the outsides of my M42 subs.
I will be correcting my backfocus distances next month hopefully.

Happy to hear any advice.

A higher quality version of the image
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Old 01-01-2019, 09:05 PM
raymo
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It is normal practice here to list equipment used and acquisition details,
which helps members to critique your work[if thats what you want], and
also allows members to compare their efforts when using similar gear.

Your pic is really dark, are you using a very slow scope? The problem with the outer stars is quite strong coma.
raymo
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  #3  
Old 01-01-2019, 09:17 PM
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multiweb (Marc)
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That's a great shot at that FL. You've got the finger and that little star next to it so you've nailed the focus and your guiding as well. The stars on the edges are because of field curvature which is inherant to most SCTs. You can get a corrector or crop your pics. The good stuff is on axis anyway so the edges don't matter much.
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Old 01-01-2019, 09:34 PM
assbutt94
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Quote:
Originally Posted by raymo View Post
It is normal practice here to list equipment used and acquisition details,
which helps members to critique your work[if thats what you want], and
also allows members to compare their efforts when using similar gear.

Your pic is really dark, are you using a very slow scope? The problem with the outer stars is quite strong coma.
raymo
Sorry! I've edited my signature!

As for the image, 2032mm f/10, 3min subs. ISO800. I didn't really stretch the histogram using curves in photoshop much, I liked how the darker "clouds" looked. I might play around with it a bit more though.

Quote:
Originally Posted by multiweb View Post
That's a great shot at that FL. You've got the finger and that little star next to it so you've nailed the focus and your guiding as well. The stars on the edges are because of field curvature which is inherant to most SCTs. You can get a corrector or crop your pics. The good stuff is on axis anyway so the edges don't matter much.
Thanks! I might try some more subs with my field flatterer(I had it off to troubleshoot issues with M42) and compose it differently.
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Old 02-01-2019, 01:00 PM
assbutt94
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I just tried to selectively stretch the histogram a little bit to brighten it up a little. I wish i did it earlier, but honestly i forgot to, the shots looked better out of the camera than my previous unguided attempts after I was done editing them.

Hi-res of Image
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Old 02-01-2019, 01:23 PM
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A very nice image and you can be proud.
Try the dodge tool in photo shop... it can brighten selected regions and the burn tool can daeken stuff...
Anyways keep them coming.
Alex
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Old 02-01-2019, 01:23 PM
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The on axis central details look excellent.
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  #8  
Old 17-02-2019, 09:53 AM
assbutt94
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Edge 8 and Astromod

Here's the result of my first night imaging using a recently acquired Edge Hd 8 and my recently modified 5dmk3. I also used various length m48 extension tubes to move the camera closer to the recommended back focus.
I still need to level my sensor correctly.
The OTA was re-collimated before capturing, not perfect but better than the collimation on the 8se's c92 test captures.

14x3min ISO 1600 Lights
20 or so darks
No flats


I'm very pleased with the Astronomik CLS CCD filter paired with the camera modification. I think the white balance is great.


This combination gives a wider FOV that is of acceptable sharpness to me. The frame was cropped slightly to remove the edges where you can see stacking.
No flats so you can see the vignetting.

Pretty chuffed considering it was just a quick test.
I bet it'll be cloudy now that I want to commit time to capturing more data.
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Old 17-02-2019, 10:05 AM
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Very nice indeed. Get some flats and it will be outstanding
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Old 17-02-2019, 11:29 AM
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Regards the coma (Which I preSume you have cropped out the last of in the later image)

On my C925, coma was quite apparent at the edges and so was vignetting. Reducing the spacing between the reducer/corrector and the camera helped both, at the expense of loosing field of view.
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Old 17-02-2019, 03:46 PM
raymo
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Very nice result, but I have always felt that one needs both modded and
unmodded cameras, as some DSOs are enhanced by the greater Ha
sensitivity, and some are definitely not, and this is one of the latter. The lack
of the other lighter bluish colours results in an overall lack of contrast.
I'll post a single frame I have handy, and see if you agree or disagree.
raymo
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Old 17-02-2019, 05:13 PM
Startrek (Martin)
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Excellent image, heaps of depth and detail but I agree with Raymo about the colour blends, this Nebula does have a white bluish appearance near the central area and some outer areas. Raymo single frame example is very similar to my 2 Eta Carina posts last week
Still an excellent image though
Cheers
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Old 17-02-2019, 05:32 PM
assbutt94
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Quote:
Originally Posted by ChrisV View Post
Very nice indeed. Get some flats and it will be outstanding
Thanks! I will get flats next time!

Quote:
Originally Posted by The_bluester View Post
Regards the coma (Which I preSume you have cropped out the last of in the later image)

On my C925, coma was quite apparent at the edges and so was vignetting. Reducing the spacing between the reducer/corrector and the camera helped both, at the expense of loosing field of view.
Thanks for the tip, I can finally fine-tune this spacing with various spacers too!


Quote:
Originally Posted by raymo View Post
Very nice result, but I have always felt that one needs both modded and
unmodded cameras, as some DSOs are enhanced by the greater Ha
sensitivity, and some are definitely not, and this is one of the latter. The lack
of the other lighter bluish colours results in an overall lack of contrast.
I'll post a single frame I have handy, and see if you agree or disagree.
raymo
Quote:
Originally Posted by Startrek View Post
Excellent image, heaps of depth and detail but I agree with Raymo about the colour blends, this Nebula does have a white bluish appearance near the central area and some outer areas. Raymo single frame example is very similar to my 2 Eta Carina posts last week
Still an excellent image though
Cheers
Thanks guys! I have caught a bit more blue in the past on 10s exposures with my camera unmodded.
I like the blue and how it blends through a purple to red in both your photos.
I might see if I can bring that blue out in the future. I agree it looks better!
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