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StuartJPP

Ghostly Iris

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It's been a long time coming...I have been absent from the DSO game for approximately 18 months due to various reasons (mostly weather!). So this bank holiday weekend looked ideal to dust the kit off and make sure that I can still get my equipment up and running. It wasn't ideal from a temperature point of view as it was a bit too warm, but have to take every opportunity as it comes along and if I didn't capture anything useful at least I could refresh my memory.

I didn't have too much trouble getting all set up and then subsequently imaging, mostly due to the fact that all my kit is labelled and ready to go, all the cables are cut to the right length, all the accessories are ready to be attached and my imaging netbook is left well alone. I have no desire to change any kit so my setup is stable and ready to be used when the opportunity arises.

Friday night was a bit of a waste as there was quite a bit of thin cloud about but last night was decent. The moon rose half way though my session but I was imaging away from it so it didn't have too much of an impact, though each sub was getting a bit brighter than the previous after a while.

Guiding was good and I achieved well below 1" RMS, though not a very tricky target in that respect. Processing is a bit rubbish as I have forgotten so much in this time! Need to practice a bit more often.

 

I have wanted to image the Ghost Nebula alongside the Iris ever since I saw it, but just never got the opportunity. Anyway, enough waffle.

Baader modified Canon EOS 6D
Canon 500mm f/4 L IS Lens @ f/4
Avalon Instruments M-Zero Mount
50x 5 minute subs @ ISO400
20x Bias
20x Flats
No Darks
APT for Data Acquisition + Dithering + Framing
PHD2 for guiding

Thanks for looking....

 

48619031017_aecd50ab1e_k.jpg
Iris and Ghost Nebulae (NGC7023 and VdB 141) by Stuart, on Flickr

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On 25/08/2019 at 20:23, paul mc c said:

Well worth the wait......nice one

 

On 26/08/2019 at 09:19, Rob Sellent said:

Aye, absolutely gorgeous image. Cracking work, Stuart :thumbright:

 

Thanks guys...👍

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Fantastic photo! You must be really happy with that. What are your sky conditions like? Bortle ?

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12 hours ago, smr said:

Fantastic photo! You must be really happy with that. What are your sky conditions like? Bortle ?

I am happy with it, however compared to Olly's it looks like I need to keep at it for a few more outings 😁

Anyway, I was in Lincolnshire, ~4 miles outside of Horncastle. Milky way is visible but it isn't super dark there. Broadband LED street lighting.

I do have a Unihedron SQM and it was reading roughly 20.87, temperature of about 18C. Whatever that equates to on the Bortle scale I'd have to investigate...hang on....Bortle 4...heading towards Bortle 3 according to Wikipedia.

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This is an awesome image but I can't help but notice the vertical banding. If you're using Pixinsight for processing, try Canon Banding Reduction script, it should get rid of all the bands 😉 otherwise it's an excellent result 🙂 

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Excellent image.

Carole

Edited by carastro
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That’s a mighty fine image, I would think the Ghost Nebula benefits from really dark skies, Olly has recorded 22 SQM on occasions at his location so don’t be too hard on yourself. 👍

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I would be very pleased with that image! Perfect composition. I see that you have the same slightly odd looking stars in the corners that I get with my 300mm f/4 Canon lens. Clearly not your doing but something about the optics of the lens. Maybe you do not worry about them, but if you do you could do like I did and make a script in PS that will make odd stars round. I learnt if from Olly here at SGL. He describes it a bit down in this thread:

 

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On 29/08/2019 at 17:13, john2y said:

This is an awesome image but I can't help but notice the vertical banding. If you're using Pixinsight for processing, try Canon Banding Reduction script, it should get rid of all the bands 😉 otherwise it's an excellent result 🙂 

I tried the Canon Banding reduction script but somehow it seems to have made things worse. So I didn't use it, I have reprocessed the image completely and can't see any banding, but that doesn't mean it isn't there.

 

On 29/08/2019 at 18:40, carastro said:

Excellent image.

Carole

Thank you Carole.

 

On 29/08/2019 at 22:03, SkyJamie said:

Lovely image Stuart, great to see you posting in here again :)

 

Thanks, good to be imagining again!

 

On 30/08/2019 at 08:38, tomato said:

That’s a mighty fine image, I would think the Ghost Nebula benefits from really dark skies, Olly has recorded 22 SQM on occasions at his location so don’t be too hard on yourself. 👍

I am not being too hard on myself, it just seem that I choose a target and shortly after posting it Olly (or one of the other top imagers) seem to post an image of the same region 😁

 

On 30/08/2019 at 13:08, ollypenrice said:

A splendid pairing, nicely done.

Olly

Thanks Olly!

 

On 30/08/2019 at 13:36, gorann said:

I would be very pleased with that image! Perfect composition. I see that you have the same slightly odd looking stars in the corners that I get with my 300mm f/4 Canon lens. Clearly not your doing but something about the optics of the lens. Maybe you do not worry about them, but if you do you could do like I did and make a script in PS that will make odd stars round. I learnt if from Olly here at SGL. He describes it a bit down in this thread:

 

I was aware of the "inverse lighthouse" artefacts on these lenses and Olly's corrections but couldn't find the method to correct them, I will try them when I reprocess the image later...

 

On 31/08/2019 at 17:24, Allinthehead said:

That's very nice and dusty. The way the Iris should be.

Thank you....

 

 

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Well I had another go at processing, I had totally forgotten that I used to use parts of the DSLR-LLRGB processing method, just goes to show how forgetful I am!

I have totally reprocessed this data but not sure if it is any better that the original or not. All I know is that I definitely need more data on this target.

@Gorann, I did try Olly's "Inverse Lighthouse" correction method, but it just seemed to smear the stars in my image (perhaps I followed the instructions incorrectly) so decided against using it.

 

Click for a larger version:
Combined_VerticalBandingSmallerStarsCropped.thumb.png.8c21af879feb31343af98327313d389a.png

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Even better - very nice indeed! It may be that the star field is too dense for Olly's method to work on this one (you could play with the the number of pixels in the Expand command). In any case, it is an effect of the lens, just like star spikes in Newtons or RC scopes, so it is obviously not a issue undless you make it one (which I was stupid enough to do).

Edited by gorann

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