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Xiga

Soul Nebula (IC1848) sHO with a Nikon D5300a

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Hi guys

Been busy the last wee while, so haven't done much imaging lately, but i did at least finally get around to processing my Soul Nebula data from a couple of weeks back. 

So this is 220 mins of Ha, and the same again of OIII, all 20 min subs. With the usual 30 flats and 50 Bias, with aggressive dithering. Shot through a SW 80ED on a HEQ5 Pro mount. 

Captured in SGP, pre-processed in APP, and post-processed in Photoshop. 

I used a slightly different method this time. Normally, i stretch the OIII data to the absolute limit, and then combine the stacks in Photoshop, but this time i used APP instead. APP has a nice feature that lets you multiply data, so i basically applied an x5 factor to the OIII data, and then assigned the Ha and OIII to G and B channels respectively (as per the standard SHO model) and then used a blend of 20% Ha and 80% OIII for the Red channel. The resulting RGB image was then imported into Photoshop for everything else. 

I'm still to decide on whether or not i prefer this method, but i do like how the colours came out with this one. I deliberately left the green alone, rather than take it out, as i think it adds more depth to the image. 

Although somewhere during my processing i noticed that the image had been converted from 16bit down to 8bit and i didn't realise until it was too late :-(  I'm still unsure how that happened exactly, perhaps after running an action, i don't know really. Anyhow, i certainly wasn't for going back to the drawing board so i decided to finish it off all the same. 

C&C welcome as always guys. Thanks for looking. 

Soul_Nebula_HST_Image_v1.4.jpg

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4 hours ago, MikeODay said:

Lovely image.  Well done!

Thanks Mike!

1 hour ago, tooth_dr said:

Great job Ciaran! Beautiful colours. 

Cheers Adam. How are you getting on with APP yourself?

1 hour ago, StargeezerTim said:

A lovely image... love those tiny stars... whats the bandwidth of your filters?

Thanks Tim. I use 2" mounted Baader filters. 7nm for Ha and 8.5nm for OIII. These ones:

https://www.firstlightoptics.com/baader-filters/baader-narrowband-ccd-emission-line-h-alpha-filters-2.html

 

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@Xiga I ran three sets of data through APP, 2 x NB and 1 x RGB.  I was impressed with the stretch that I got with the RGB M42, except that the stars all went quite bloated too.  I'd need to look into the setting because Im guessing it has potential, but currently my DSS processed versions appear better.

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52 minutes ago, tooth_dr said:

@Xiga I ran three sets of data through APP, 2 x NB and 1 x RGB.  I was impressed with the stretch that I got with the RGB M42, except that the stars all went quite bloated too.  I'd need to look into the setting because Im guessing it has potential, but currently my DSS processed versions appear better.

IIRC, I think there is a Threshold setting on the RHS panel that helps to control stars from blowing out. There's a button you can click on that brings up a really useful Help Panel with descriptions and pictures of what each setting does. You should be able to find it pretty easily that way. Certainly for a target with really large stars such as M42 it would be useful. But beyond stretching (and a little star size control) the only other thing I currently use APP for is gradient reduction (it's called Light Pollution Removal). It's pretty much essential to run. But after that, it's Photoshop all the way for me.

Good luck!

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19 minutes ago, Xiga said:

IIRC, I think there is a Threshold setting on the RHS panel that helps to control stars from blowing out. There's a button you can click on that brings up a really useful Help Panel with descriptions and pictures of what each setting does. You should be able to find it pretty easily that way. Certainly for a target with really large stars such as M42 it would be useful. But beyond stretching (and a little star size control) the only other thing I currently use APP for is gradient reduction (it's called Light Pollution Removal). It's pretty much essential to run. But after that, it's Photoshop all the way for me.

Good luck!

Thanks Ciaran!  The only other thing I've noticed that when I click on the top drop down menu for linear, calibrated, registered etc they all look the same, but I thought they were meant to be different (sorry for cluttering your thread)

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1 hour ago, tooth_dr said:

Thanks Ciaran!  The only other thing I've noticed that when I click on the top drop down menu for linear, calibrated, registered etc they all look the same, but I thought they were meant to be different (sorry for cluttering your thread)

Yeah that doesn't sound right, you should definitely be seeing a difference between linear and l-calibrated.

Probably best to start a separate thread in one of the other forums and i'll see if I can help. That way others can benefit from any solutions that come of it.

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What was the sensor temperature reported as when you imaged this. It has been cold recently.

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3 hours ago, Adam J said:

What was the sensor temperature reported as when you imaged this. It has been cold recently.

Hi Adam

Sorry I've no idea. I don't think my Nikon reports the sensor temperature, unlike with Canons. I do know however, that the actual outside temperature on the two nights I imaged this, was -3C and 0C. It was frigging freezing! Thank goodness for Team Viewer. Once I was setup, I was able to stay inside and monitor the guide graph and FWHM's of the subs. I only went out to re-focus if the FWHM's started to change substantially, and from memory I don't think they did. The seeing was better on the 2nd night though, as I had better FWHM's that night, even though I was using the OIII filter which has a slightly wider bandpass.

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Congratulations on a splendid Soul Nebula.

On 22/01/2018 at 02:39, Xiga said:

 I deliberately left the green alone, rather than take it out, as i think it adds more depth to the image.

I am finding this very useful too to help with the tonal range within the palette, though I am removing the majority.

For constructive criticism, the background on my monitor does show distinctly blue, a relatively quick fix.

Top notch image and processing, well done Ciaran.

Edited by Barry-Wilson
typo
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2 hours ago, Barry-Wilson said:

Congratulations on a splendid Soul Nebula.

I am finding this very useful too to help with the tonal range within the palette, though I am removing the majority.

For constructive criticism, the background on my monitor does show distinctly blue, a relatively quick fix.

Top notch image and processing, well done Ciaran.

Thanks Barry. 

I am always after constructive criticism, the more the merrier actually, it all helps in the learning process. Thanks for pointing out the overly blue background, not quite sure how i missed that! I've neutralised it in the version below (at least i hope i have!).

Cheers!

 

Soul_Nebula_HST_Image_v1.4.jpg

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That is a fantastic image, and very inspiring for us dslr users. I have just started using my own Ha and OIII filters (Astronomik 12nm) and now I think I need to start all over again with my previous rgb shots of emission nebulas. Did you have a decent sky when you captured this ? I played around a little in PS with your image, and when I was done i had some changes to the colors and also just a tad of selective noise reduction (I may post it here with your permission). But that is just my personal taste...

Thanks for sharing.

Ragnar

Edit : What ISO did you use, and may I ask what is your technique for fighting bloated stars ? You have very nice star shapes here.

Edited by lux eterna
I forgot...
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2 hours ago, lux eterna said:

That is a fantastic image, and very inspiring for us dslr users. I have just started using my own Ha and OIII filters (Astronomik 12nm) and now I think I need to start all over again with my previous rgb shots of emission nebulas. Did you have a decent sky when you captured this ? I played around a little in PS with your image, and when I was done i had some changes to the colors and also just a tad of selective noise reduction (I may post it here with your permission). But that is just my personal taste...

Thanks for sharing.

Ragnar

Edit : What ISO did you use, and may I ask what is your technique for fighting bloated stars ? You have very nice star shapes here.

Thanks Ragnar! I'm really enjoying doing narrowband I have to say. Almost to the point whereby I'm a little disappointed if I have to shoot something in RGB!

My skies are pretty good, about MAG 20.5 according to the link below. But in all honesty, the quality of the skies doesn't matter so much with NB filters. That's the beauty of them! I decided to go with the Baader ones to have a slightly narrower bandpass, to help with contrast, but it does mean I need slightly longer exposures as a result. But your Astronomik ones should work just fine as well.

https://www.lightpollutionmap.info/#zoom=15&lat=7287611&lon=-692294&layers=B0FFFTFFFF

Please, be my guest and post up your version, I'd love to see it. The best way to learn is to see what others can do with the same data. As far as noise reduction is concerned, I like to go as light as possible on this as I'm very sensitive to too much NR in an image. Unfortunately you will always need to do some when doing NB on a DSLR, due to the bayer matrix lowering the efficiency. If I'd captured the same amount of exposure as above, only with a cooled mono camera, then you probably wouldn't need to do any NR on the image at all (how amazing would that be!).

I only ever use ISO 200 with my D5300. I never, ever change it. No need, as the read noise is already low enough (due to the nice Sony sensor) and it means I can maximise the Dynamic Range too, which is important. If you have an older Canon DSLR, then this won't apply to you. In all likelihood you will probably need to stick to around ISO 1600 in order to keep the read noise down.

These days my guide graph in PHD2 usually hovers around the 0.6-0.8" range for RMS. I've even seen it go under 0.5" recently but the seeing must have been exceptional that night. I do have the Rowan Belt Mod for my HEQ5 Pro though, and I've also been using the new Predictive PEC algorithm in PHD2, and that has definitely helped bring the RMS down a bit. All of which means I'm able to get decent stars, even with 20 min long subs. They won't challenge the big boys with their triplets and mono cameras with Astrodon filters any time soon though! lol. And as for processing, I haven't been doing anything too specific to keep them under control, just a mixture of DDP stretching and careful curves (like an ArcSinh shape). Are you doing star reduction in your images? Most images benefit from this, even if it's just a little. I usually do it on most of mine.

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2 hours ago, Xiga said:

I only ever use ISO 200 with my D5300. I never, ever change it. No need, as the read noise is already low enough (due to the nice Sony sensor) and it means I can maximise the Dynamic Range too, which is important. If you have an older Canon DSLR, then this won't apply to you. In all likelihood you will probably need to stick to around ISO 1600 in order to keep the read noise down.

Its  interesting, however I would pitch my cooled 550D ISO800 against your uncooled D5300 at ISO200 quite happily especially in summer. When you are shooting long 20min subs read noise is not a big factor as it will not build up due to the small number of subs in total that leaves thermal noise as the biggest factor by far. A KAF8300 has 8e read noise and people do not complain about it being noisy and its because of the long subs. I don't know what unity gain is for the D5300 but I would keep to that and not go below it especially if it allows you to get away with shorter subs as dynamic range is not such an issue in that instance anyway.  Happy to perform a like for like comparison if you can post just the H-a for the target as I do have soul nebula data with the 550D at a very similar focal length. 

Edited by Adam J
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Thank you Ciarán for explaining things, in your very informative post. Having a modded 16MP d7000 myself, now I am tempted to get a used D5300 just to get 24 MP - and still have slightly better sensor performance. ISO 200 and NB filters, that can explain the nice and small stars. I often use ISO 400 with my D7000, maybe I will try 200 as well. I also have a belt modded HEQ5 Pro, but I guide with a standalone NexGuider as I need to be portable and want no pc in the field (too much power requirements).

Sometimes I use StarShrink in small portions to control star sizes, but I also use Straton.exe to remove stars before stretching, and then when I put the stars back there is no need to shrink them.

Anyway, here is my fiddling with the picture. I´m not saying it´s better, just different. Just like taste is different... I used selective color, a little levels and curves, just a tad denoise in darker areas, then tuned color saturation.

Ragnar

soul.thumb.jpg.bf429236647cc0c7a0ce8c7fc821eb73.jpg

 

 

 

 

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9 hours ago, Adam J said:

Its  interesting, however I would pitch my cooled 550D ISO800 against your uncooled D5300 at ISO200 quite happily especially in summer. When you are shooting long 20min subs read noise is not a big factor as it will not build up due to the small number of subs in total that leaves thermal noise as the biggest factor by far. A KAF8300 has 8e read noise and people do not complain about it being noisy and its because of the long subs. I don't know what unity gain is for the D5300 but I would keep to that and not go below it especially if it allows you to get away with shorter subs as dynamic range is not such an issue in that instance anyway.  Happy to perform a like for like comparison if you can post just the H-a for the target as I do have soul nebula data with the 550D at a very similar focal length. 

Yes, you're right Adam. With long subs it's the thermal noise, rather than the read noise, which becomes the most important factor. I have read that the D5300 has a lot less thermal noise than similarly priced Canons (although i have no way to test or prove that unfortunately) but with your 550D being cooled i'd say yours would have an advantage overall. The closest ISO to Unity Gain on the D5300 is ISO 200, which is why i use it solely. I suppose i could get away with ISO 400 as well, but i might only venture there if i ever go after a really faint target that needs subs longer than 20 mins (unlikely as it's already hard enough over here getting enough 20 min long stretches of clear sky to create a single image, lol). 

I've posted a jpeg of one of my Raw Ha subs (uncalibrated, of course) below. The only thing it's had done is an Auto-DDP stretch in APP. We have completely different scopes too remember, lens vs mirror, FR (6.375 Vs 5), and aperture (80mm vs 130mm), so i'm not sure how much of a like for like comparison can even be done, and what it would even prove tbh. But here it is anyway, just for the craic! :-)

 

Soul_Nebula_1200sec_ISO200_filter0_Ha_frame2-St.jpg

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7 hours ago, lux eterna said:

Thank you Ciarán for explaining things, in your very informative post. Having a modded 16MP d7000 myself, now I am tempted to get a used D5300 just to get 24 MP - and still have slightly better sensor performance. ISO 200 and NB filters, that can explain the nice and small stars. I often use ISO 400 with my D7000, maybe I will try 200 as well. I also have a belt modded HEQ5 Pro, but I guide with a standalone NexGuider as I need to be portable and want no pc in the field (too much power requirements).

Sometimes I use StarShrink in small portions to control star sizes, but I also use Straton.exe to remove stars before stretching, and then when I put the stars back there is no need to shrink them.

Anyway, here is my fiddling with the picture. I´m not saying it´s better, just different. Just like taste is different... I used selective color, a little levels and curves, just a tad denoise in darker areas, then tuned color saturation.

Ragnar

soul.thumb.jpg.bf429236647cc0c7a0ce8c7fc821eb73.jpg

Hi Ragnar

That's really nice, thanks for posting it. :thumbright: This looks more like the kind of colour scheme i've been doing myself, up to this particular target, when i decided to deliberately leave more green in and turn the oranges a bit more golden. Of course, it's all down to personal taste with a false colour image, so there's no right or wrong :smiley: I can see the extra NR you have applied to. For me, it's a tad too much for my own taste (i'm very sensitive to too much) and i probably under-cooked mine a bit tbh, so maybe somewhere between the two would have been the sweet spot. 

You have a really nice camera with the D7000. The closest ISO to Unity Gain for it is also ISO 200, similar to my own, so as long as you have the tracking for it then i would experiment with it for a while and see what you think. 

I know what you mean about keeping power requirements down, and wanting to keep the laptop out of the equation, i've been there. But imho, if you are looking to do Bi-Colour imaging with a DSLR, then that will realistically mean having to do Ha on one night and OIII on another. I'm guessing you get some nice long, dark nights up there in Sweden, but seriously, you are going to have to factor in multiple session imaging. And that will mean plate solving, which will require a laptop. But here's the beauty of NB imaging, you can do it from home, you don't need dark skies. When i image, i setup in my driveway (which has streetlights nearby, and even an all-weather football pitch only 200 yards away!) and i drag power leads out there to power my dew heaters (and the laptop itself sometimes), so power isn't an issue. Something to think about (unless of course you have no view of the sky where you live).

But even if you have no option but to go mobile, there are solutions out there. I use the adapter below for my camera. It will power it for much, much longer than any imaging session i could ever do, and it can even double-up as a mobile phone charger the rest of the time:

https://www.amazon.co.uk/Ex-Pro®-16000mAh-Rechargeable-Battery-replacing/dp/B01BKSY1PK

As for the laptop, i picked up a refurbished Lenovo X230 laptop off ebay for £150. The battery lasts for about 10 hrs. It's less in cold weather obviously, but still longer than any single imaging session i've ever done. 

That just leaves the mount & dew heaters. Something like the Celestron Lithium Powertank for the mount (small, light, and enough to get the job done), and a more traditional higher AHr rated Lead Acid powertank for the dew heaters, and you'd be in business. 

 

 

 

 

Edited by Xiga

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Hi Ciarán ,

It certainly is a pleasure to process such good data. I guess I´m just used to more red biased colors from my own rgb images.:happy11: But from now on I will do more Ha OIII imaging - thanks for this wake-up call.

Re. iso, I will definitely go lower now. 200, or maybe even 100 (will have to test that after reading this http://dslr-astrophotography.com/iso-values-nikon-cameras/)

Yes, I am bound to be portable due to limited sky views at home - but I also enjoy sitting watching a remote dark sky and listen to the camera clicking away... I did not know such low power laptops exist, an extra battery would provide for a complete night. But I do not need plate solving. I use an 8" Android tablet to control my camera(s), and when needed I have a transparent plastic overlay on which I mark some reference stars with a whiteboard marker, for the next imaging session. I also make a note on what rotational angle the camera/focuser has. In fact, I often have this prepared in advance of the first imaging session, with the help of screen shots from Stellarium on my home pc - it saves valuable time under the stars.

The D7000 takes very little power, 2x li-ion 3000mah 18650 batteries last for a long and cold night, while the mount, guider and dew heaters run from a AGM battery.  

Thanks for info & inspiration. May the darkness be with you.

Ragnar

 

 

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1 hour ago, lux eterna said:

Hi Ciarán ,

It certainly is a pleasure to process such good data. I guess I´m just used to more red biased colors from my own rgb images.:happy11: But from now on I will do more Ha OIII imaging - thanks for this wake-up call.

Re. iso, I will definitely go lower now. 200, or maybe even 100 (will have to test that after reading this http://dslr-astrophotography.com/iso-values-nikon-cameras/)

Yes, I am bound to be portable due to limited sky views at home - but I also enjoy sitting watching a remote dark sky and listen to the camera clicking away... I did not know such low power laptops exist, an extra battery would provide for a complete night. But I do not need plate solving. I use an 8" Android tablet to control my camera(s), and when needed I have a transparent plastic overlay on which I mark some reference stars with a whiteboard marker, for the next imaging session. I also make a note on what rotational angle the camera/focuser has. In fact, I often have this prepared in advance of the first imaging session, with the help of screen shots from Stellarium on my home pc - it saves valuable time under the stars.

The D7000 takes very little power, 2x li-ion 3000mah 18650 batteries last for a long and cold night, while the mount, guider and dew heaters run from a AGM battery.  

Thanks for info & inspiration. May the darkness be with you.

Ragnar

 

 

Wow, I take my hat off to you Sir, with your DIY solution to manual plate solving. Good thinking :icon_biggrin: 

I'm lazy, so I will stick to using SGP to get me on target :tongue:

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