The Iris Nebula - C4 NGC7023

[JimothyC]

After a few failed attempts at capturing a nebula, mainly due to locating the things in the sky, I've managed to get my first reasonable deep sky image of something. This is all thanks to the iOptron CEM25P mount I treated myself to the other day.

Setup is as follows:

Altair 70ED Travel Scope (Non apo doublet)
Altair 1.0x Field Flattener
iOptron CEM25P Mount
Nikon D7500 (Unmodded)
Baader Neodymium Filter

23 x 600s @ISO800  Lights + Darks, Flats and Bias
Shot from Bortle 4 (allegedly) skies in Buckinghamshire.

It's also my first go at trying to process something in PixInsight. I've been giving the trial a good workout using these tutorials http://www.lightvortexastronomy.com/tutorials.html which are excellent. 

Anyway, enough rambling. This is the final result. 

I'm a bit worried I've over processed it a bit. But I'm pretty happy that I can get a result like this with a cheapish 70mm scope from my mum's back garden. 

Any questions, feedback or tips most welcome.

[Adreneline]

An excellent start! Well done.

I am by no means an expert with PI (I've only been using it for 18 months!) but did you use the SCNR process on the image at any stage. On my screen at least it appears to have quite a strong hint of green; using the default settings work just fine and are best used after BN/CC.

Re. over processing I have learnt to process to the point I think it looks ok and then go and back everything off a tad - it is so easy to push things too far, or to know when to stop.

I've not had a go at this target myself so I might give it a go and see what happens.

Good luck!

Adrian

[JimothyC]

I thought I had, but I think it must have been quite early in the process. Here's an updated version with SCNR applied. I think it definitely helps things look a bit more natural.  The challenge here is trying to push it to bring some definition in the dark clouds. I think I just need to more exposure time to bring out some more detail. 

[wimvb]

That looks great. More data should bring the noise down (this is a faint object). You can also try noise reduction. Do you have Warren Keller's book "Inside PixInsight"? Highly recommended, as are the lightvortexastronomy tutorials.

[JimothyC]

Yep it is pretty noisy. I think I've pushed the images a bit too hard in processing. Or perhaps it's a warm DSLR sensor to blame, it's not been exactly cold these last few evenings. 

Do you think I should up the exposure length? 600s was giving me a histogram roughly in the middle. 

I've just received my requisite copy of 'Making Every Photon Count'. So once I've ploughed through that, I'll take a look at the pixinsight one. Thanks

[wimvb]

2 hours ago, JimothyC said:

Do you think I should up the exposure length? 600s was giving me a histogram roughly in the middle. 

Try too keep the histogram left of the middle. It seems that 600 s is the longest you can expose per frame at this ISO setting. But you can decrease ISO to 400, and use the 600 s, or decrease the exposure time at ISO 800. The more light pollution you have, the longer total exposure time you will need in order to bring the noise down. This means, more subs to stack.

2 hours ago, JimothyC said:

Or perhaps it's a warm DSLR sensor to blame, it's not been exactly cold these last few evenings.

Temperature counts. Here's my attempt at the iris, with a cooled camera at -20 C

https://www.astrobin.com/318629/C/?nc=user

[Selborne]

I had a chance to get out in the garden last evening, had a go at capturing NGC 7023 - Iris Nebula, only managed to get 12 good shots, 240sec x 12, combined in Photoshop with Mean Stacking.  The dew was super heavy and currently I do not have any dew heaters (next purchase) so lost the battle after around 2 hours. 

One interesting point is I captured these shots with the long exposure noise reduction switched on with the Sony A7Rii, so each shot took 8 mins to take and save, but as a result the noise levels were next to zero at 800 ISO, and at the end of the day the noise is always our enemy, I do not take flats or darks, just shots straight from the camera in RAW and stack in photoshop.  With the noise reduction switched on, I do loose a few of the really dim stars, but to be honest, there is always way to many stars in my shoots.

The skies we clear with good viewing, about 5 miles from a major town, so light pollution not to bad.  I did not use any filters and the camera is not modified.  It was taken using the Sony A7Rii coupled to my Skywatcher 100 ED Pro Esprit Scope, mounted on my HEQ6 mount and guided using 50ED Skywatcher Guide Scope and Altair Astro ASI130mm camera, with PHD2 of course.

I am very happy with the final shot,

thanks

Jamie