NGC6960 Western Veil 2018-07-15

[The Thing]

I've been wrestling with processing this trying to knock back the stars and bring out the nebulosity, I hope it's not too leery.
42 x 300s at unity gain (120) and -15c.


Image date, time and location:        2018-07-15 00:00 UTC Manche, France
Telescope aperture and focal ratio:   TS1506UNC f4, TS Komakorr
Camera and filters used:              ZWO ASI294MC Pro, UV filter
Processing applied:                   PixInsight, Gimp 2.9

[MarkS]

Excellent image!

I know what you mean about star reduction.  Imaging this area in RGB tends to make the stars bloaty when it is stretched enough to show the nebulosity.

I particularly like the area of dust above the Witches Broom because it doesn't appear in many images - I think most people accidentally remove it during background extraction.

Mark

[Carole]

Great FOV including Pickerings triangle which I find more difficult to process than the East and Western veils.

I thought the colour looked a bit washed out so I took it into PS to see if it could be enhanced and found that the image is actually clipped though was surprised as the image doesn't look clipped.

Anyway regardless, it's a fine image but for my taste I prefer slightly stronger colours. 
Good stuff.

Carole

[The Thing]

Hi Carole, thanks for the feedback. If there isn't enough colour maybe you need to adjust you monitor! Looks pretty vivid to me.

[The Thing]

Thanks Mark, I may need a uv/ir filter to reduce bloat, or less beer. At the moment my setup is unfiltered. I have a Baader Neodymnium 2" I could use which would do the job but may alter the colour balance a bit. Unless I can wangle my uv/ir clip filter into the imaging train somehow.

[Carole]

Hi Carole, thanks for the feedback. If there isn't enough colour maybe you need to adjust you monitor! Looks pretty vivid to me.

Vivid? Seriously?  Well I will take a look on one of my laptops and see if it is any different on there. 

Carole

[MarkS]

Hi Carole, thanks for the feedback. If there isn't enough colour maybe you need to adjust you monitor! Looks pretty vivid to me.

It's not looking vivid to me either.  I would describe it as subdued.

Mark

[ApophisAstros]

i've got a topnotch laptop, and it does look washed out by stars , hard to see the detail.but good FOV .At gain of 120 in sql reading of 21 ish the recommended exposure time is 1.7 minute subs with my f6 refractor. Have you tried much shorter exposures.
In skies like Cairds DSC for darker skies i will try gain 50 and 4 minute subs and still be shot noise limited.
Roger

[The Thing]

Hi Carole, thanks for the feedback. If there isn't enough colour maybe you need to adjust you monitor! Looks pretty vivid to me.

It's not looking vivid to me either.  I would describe it as subdued.

Mark

I'll up the colour and recalibrate my monitor. But it still looks vivid on my phone and kindle...

[The Thing]

Hi Roger

Sharpcaps chip characterisation function recommended 8.2s subs at gain 115 (120 is unity gain on this camera) but 1600 of them! I did a test of 1000 subs but have only tried a quick stack of 249 which seems to be DSS limit. The results were very good so I will go down this route in future. I need to try it on pixinsight when I've got a few hours.

[The Thing]

Here's a brighter version. I love the GIMP 2.10, I think I've managed to knock back the stars a bit as well. BTW the full size image is half original size.

[Carole]

Ah, much better colour Duncan. 

What method are you using to try to shrink the stars, I have a couple of methods for photoshop if you are interested? 

Carole

[The Thing]

On my monitor it looks horrendously lurid, and I've recalibrated with my Spyder5 and DisplayCAL(free) this morning so that is not a factor.

For the stars I'm using Pixinsight's MorphologicalTransformation [sic] works well if you get the settings right like most things. I may need to do a couple of iterations to shrink stars more. Also I am getting to grips with StarMask and RangeSelection for brightness masks. Robert has suggested shorter subs and I know he's right as the images I've done at 120s and 30s as well as the 8.2s ones mentioned below have much smaller stars. The temptation of longer subs is that they show a nice low noise image on the capture program preview when stretched. Clear skies at the end of the week so more chance to experiment with the ASI294.

[Carole]

I have checked my monitor calibration as well and it is fine, so not sure what is going on. 

I know what you mean about the shorter subs having smaller stars, I get the same between using the RGB filters with shorter subs and the Luminance stars being a fair bit larger as the subs are longer and the lum filter probably lets in more light anyway.   

Ideally you want the extra nebulosity with the longer subs but the smaller stars with the shorter subs, its a balancing act. 

I wonder if you could do some of each, and try to combine in some sort of post-processing magic.

Carole

[The Thing]

Ideally you want the extra nebulosity with the longer subs but the smaller stars with the shorter subs, its a balancing act. 

I wonder if you could do some of each, and try to combine in some sort of post-processing magic.

Carole

Basically that's what Robert has suggested So I'll set Pixinsight off stacking 1000 x 8.2s subs this afternoon.

[JohnP]

Hi Dunc,

Its an excellent image - loads of fine detail so well done. Regarding colours I would say first is as Mark described a little subdue - for the second you have over saturated - bit too much...

What I tend to is look for a good replica image online & then use that as a starter for my own image. i.e. have two windows open & flick between - at least that way monitor calibration is a little less crucial.

Fine image though - I love it - would look great in B&W

John

[The Thing]

Thanks John, each to his own taste I suppose. I have worked up another version in PI only with better control over the saturation, more stars and some sharpening that the other version don't have. Could go on for ever!

[MarkS]

Here's what I do as a double check on screen calibration.  Display the image of anything that includes a Macbeth colour chart on the screen (you don't have to own the chart).  Now take a photo of the screen (in a darkish room).

Perform neutral processing of the raw photo in Photoshop (making sure the grey squares are free of tint).  The original image and the photo of the original should be almost identical.

Standard raw conversion in Photoshop adds lots of saturation and toning because that's what everyday photographers want to see.  But to perform neutral processing in PS do the following:

1) Set the colour space to Adobe RGB in the raw converter
2) Set the process version to 2010 (and definitely not 2012)
3) Set the tone curve to linear
4) Set the Blacks, Brightness and Contrast sliders to zero
5) Adjust temperature and tint to make the grey squares free of any tint
6) Adjust the exposure slider to match the brightness of the original image

This should prove that the whole front-to-back process from camera to screen is behaving itself and that the screen is displaying exactly what the camera sees.

Mark

[ApophisAstros]

Here's what I do as a double check on screen calibration.  Display the image of anything that includes a Macbeth colour chart on the screen (you don't have to own the chart).  Now take a photo of the screen (in a darkish room).

Perform neutral processing of the raw photo in Photoshop (making sure the grey squares are free of tint).  The original image and the photo of the original should be almost identical.

Standard raw conversion in Photoshop adds lots of saturation and toning because that's what everyday photographers want to see.  But to perform neutral processing in PS do the following:

1) Set the colour space to Adobe RGB in the raw converter
2) Set the process version to 2010 (and definitely not 2012)
3) Set the tone curve to linear
4) Set the Blacks, Brightness and Contrast sliders to zero
5) Adjust temperature and tint to make the grey squares free of any tint
6) Adjust the exposure slider to match the brightness of the original image

This should prove that the whole front-to-back process from camera to screen is behaving itself and that the screen is displaying exactly what the camera sees.

Mark

or let windows do it, in control panel and typing calibrate display in search bar.

Roger

[Carole]

Yes that's the method I used Duncan.

Carole

[The Thing]

I use a Datavision  Spyder 5 and DisplayCal with Argyll CMS corrected for ambient light. I suspect it's fairly accurate at setting up my monitor for creation of images for web use. My laptop has the same. Maybe my eyes are screwy!😉

[Carole]

Maybe John's idea is a good one:

What I tend to is look for a good replica image online & then use that as a starter for my own image. i.e. have two windows open & flick between - at least that way monitor calibration is a little less crucial.

Carole

[JohnP]

..Not strictly technical I know but at least gets you close...

[MarkS]

Thanks Mark, I may need a uv/ir filter to reduce bloat, or less beer. At the moment my setup is unfiltered. I have a Baader Neodymnium 2" I could use which would do the job but may alter the colour balance a bit. Unless I can wangle my uv/ir clip filter into the imaging train somehow.

I've just noticed your comment about a UV/IR filter.  Yes you definitely need to use one.  Blocking the IR helps prevent star bloat and it gives a better colour balance.

Mark