Horsehead Help-Processing Advice

[Matt S]

Dear all

I wonder if you may be able to help me get more out of some dubious data..?

I started AP during the Spring of 2020, using s small 'frac. Having caught the AP bug (fortunately, not the 'other' bug ) I migrated to a higher focal length with my CPC925 controlled by a ZWO ASI Air Pro (to manage my expectations). That journey has been anything but painful(!), but if it were easy, then our labours would all feature in National Geographic...

A little over a week ago, I imaged the Horsehead Nebula: 3min subs, totalling 2:50hrs integration. Regrettably, the Moon was c.70% waxing and close to the target. I have saved the calibrated (inc Darks, Flats and Bias') and stacked DSS file in Dropbox: https://www.dropbox.com/s/0b5kht08g52im ... e.fit?dl=0

A simple stretch will reveal plenty of stray light and a horrendous lens flare artefact, either caused by the Moon, Alnitak or both. In my processed image https://www.dropbox.com/s/yjo74dfjimy90 ... .tiff?dl=0 you'll see I've cropped much of that out to spare my blushes. The larger stars reveal the effects of atmospheric refraction (blue shifted North, yellow South) for a target that reached no higher than 36deg alt. But 'hay', that is definitely a horse's head.

I would be grateful if you could have a crack at processing the DSS file in StarTools and sharing your log file, along with any tips. I am a big fan of this software, which has enabled me to explore AP on a budget, but am aware that my rudimentary skills have stalled. I appreciate that the conditions described above were far from ideal, but 'needs must' in the Atlantic-driven skies of the UK.

Thanks for reading this post.

Stay safe and clear skies
Matt

[Gear: wedge-mounted CPC925 (reduced to F6.3), ASI Air Pro, ASI 294MC Pro main camera, ASI 120MM guide camera, running StarTools v1.5.369]

[Carles]

Hello

since there's that big reflection..plus other on the opposite side, I've first binned, then Crop it off, Wipe, with Uncalibrated 1 , reducing Aggressivity to around 20%, rest by default. Followed by FilmDev to around 95% Digital Develp. And after that Contrast, HDR -Tame, Sharp, Colour- Legacy cap green 50% dark and bright saturation 100%, and saturation amount reduced to 200%.

SuperStructure- Isolate strenght to 70%, and final Denoise.
Left some noise as to keep details. I guess colour could be tweaked too, but is a matter of taste ?

Horse D.jpg (603.77 KiB) Viewed 4475 times

used StarTools 1.8.525.

hope it helps

Carles.

[Matt S]

Hi Carles
Thank you so much for having a crack at this, and for the tips.
I’m using an older version of StarTools to yours, so maybe there are a few elements I cannot replicate. I am impressed, particularly with respect to the more natural looking star colours and detail left.
Could you post your log so that I can go away and see ‘how’ you did it?
In your experience, do you believe that horrible reflection is from the Moon or Alnitak? Would 1min, vice 3min, subs be better? Also, how did you eliminate the atmospheric refraction effects?
So much to learn-thank you again!
Matt

[Carles]

Hi Carles
Thank you so much for having a crack at this, and for the tips.
I’m using an older version of StarTools to yours, so maybe there are a few elements I cannot replicate. I am impressed, particularly with respect to the more natural looking star colours and detail left.
Could you post your log so that I can go away and see ‘how’ you did it?
In your experience, do you believe that horrible reflection is from the Moon or Alnitak? Would 1min, vice 3min, subs be better? Also, how did you eliminate the atmospheric refraction effects?
So much to learn-thank you again!
Matt

Hi Matt,

You should try the latest 1,8 version, is very powerful : )
But I guess most of it can be done with 1.5, too.
I am not sure about that horrible reflection... is by any chance any sort of light leak in your system? I wouldn't say is Alnitak nor the Moon

[Gear: wedge-mounted CPC925 (reduced to F6.3), ASI Air Pro, ASI 294MC Pro main camera, ASI 120MM guide camera, running StarTools v1.5.369]

Do you use guide scope or OAG ? are your calibration frames OK ?

Captura de pantalla 2022-02-19 212013.jpg (551.53 KiB) Viewed 4464 times

seems a reflection from outside.. ? but seem to have "difraction rings".. not sure.
about the workflow, here's the log

Code: Select all

--- Wipe
Parameter [Synthetic Dark/Bias] set to [Adaptive Multi-Axis Bias Conservative]
Parameter [Gradient Edge Behavior] set to [Grow opposite axis]
Parameter [Synthetic Flats] set to [Vignetting]
Parameter [Sampling Precision] set to [256 x 256 pixels]
Parameter [Dark Anomaly Filter] set to [4 pixels]
Parameter [Gradient Falloff] set to [75 %]
Parameter [Synth. Bias Edge Area] set to [100 %]
Parameter [Gradient Aggressiveness] set to [19 %]
Parameter [Correlation Filtering] set to [Off]
--- Photographic Film Development Emulation
Parameter [White Calibration] set to [Use Stars]
Parameter [Gamma] set to [1.40]
Parameter [Skyglow] set to [0 %]
Parameter [Digital Development] set to [90.99 %]
Parameter [Blue Luminance Contrib.] set to [100 %]
Parameter [Green Luminance Contrib.] set to [100 %]
Parameter [Red Luminance Contrib.] set to [100 %]
Parameter [Dark Anomaly Headroom] set to [5 %]
Parameter [Dark Anomaly Filter] set to [14.7 pixels]
--- Contrast
Parameter [Expose Dark Areas] set to [Yes]
Parameter [Brightness Retention] set to [Off]
Parameter [Precision] set to [256 x 256 pixels]
Parameter [Shadow Detail Size] set to [10 pixels]
Parameter [Locality] set to [50 %]
Parameter [Shadow Dyn Range Alloc] set to [50 %]
--- HDR
Parameter [Signal Flow] set to [Tracked]
Parameter [Quality] set to [Medium]
Parameter [Gamma Shadow (Lift)] set to [1.00]
Parameter [Gamma Highlight (Tame)] set to [1.94]
Parameter [Gamma Smoothen] set to [20.0 pixels]
Parameter [Context Size] set to [3x3 pixels (0.18% image W, 0.23% image H)]
Parameter [Shadows Detail Boost] set to [30 %]
Parameter [Highlights Detail Boost] set to [43 %]
--- HDR
Parameter [Signal Flow] set to [Tracked]
Parameter [Quality] set to [Medium]
Parameter [Gamma Shadow (Lift)] set to [1.00]
Parameter [Gamma Highlight (Tame)] set to [1.25]
Parameter [Gamma Smoothen] set to [20.0 pixels]
Parameter [Context Size] set to [26x26 pixels (1.54% image W, 1.95% image H)]
Parameter [Shadows Detail Boost] set to [64 %]
Parameter [Highlights Detail Boost] set to [52 %]
Mask used (BASE64 PNG encoded)


Mask used (BASE64 PNG encoded)


--- Wavelet Sharpen
Parameter [Structure Size] set to [Medium]
--- SNR-aware Wavelet Sharpening
Parameter [Protection] set to [Shadow/Highlights]
Parameter [Scale 1] set to [100 %]
Parameter [Scale 2] set to [100 %]
Parameter [Scale 3] set to [100 %]
Parameter [Scale 4] set to [100 %]
Parameter [Scale 5] set to [100 %]
Parameter [Mask Fuzz] set to [4 pixels]
Parameter [Amount] set to [735 %]
Parameter [High SNR Size Bias] set to [75 %]
Parameter [Low SNR Size Bias] set to [0 %]
Parameter [Dark/Light Enhance] set to [32% / 68%]
--- Wavelet Sharpen
Parameter [Structure Size] set to [Small]
--- SNR-aware Wavelet Sharpening
Parameter [Protection] set to [Shadow/Highlights]
Parameter [Scale 1] set to [100 %]
Parameter [Scale 2] set to [100 %]
Parameter [Scale 3] set to [100 %]
Parameter [Scale 4] set to [100 %]
Parameter [Scale 5] set to [100 %]
Parameter [Mask Fuzz] set to [4 pixels]
Parameter [Amount] set to [964 %]
Parameter [High SNR Size Bias] set to [50 %]
Parameter [Low SNR Size Bias] set to [0 %]
Parameter [Dark/Light Enhance] set to [50% / 50%]
--- Color
Parameter [Bias Slider Mode] set to [Sliders Reduce Color Bias]
Parameter [Style] set to [Artistic, Not Detail Aware]
Parameter [LRGB Method Emulation] set to [RGB Ratio, CIELab Luminance Retention]
Parameter [Matrix] set to [Identity (OFF)]
Parameter [Dark Saturation] set to [Full]
Parameter [Bright Saturation] set to [Full]
Parameter [Saturation Amount] set to [210 %]
Parameter [Blue Bias Reduce] set to [1.00]
Parameter [Green Bias Reduce] set to [1.25]
Parameter [Red Bias Reduce] set to [1.32]
Parameter [Mask Fuzz] set to [1.0 pixels]
Parameter [Cap Green] set to [53 %]
Parameter [Highlight Repair] set to [Off]
Mask used (BASE64 PNG encoded)


--- Shrink
Parameter [Mode] set to [Dim]
Parameter [Halo Extend] set to [1 pixels]
Parameter [Iterations] set to [1]
Parameter [Regularization] set to [0.00]
Parameter [Color Taming] set to [0 pixels]
Parameter [De-ringing] set to [Off]
Parameter [Un-glow Strength] set to [Off]
Parameter [Un-glow Kernel] set to [Off]
--- Super Structure
Parameter [Detail Preservation] set to [Linear Brightness Mask Darken]
Parameter [Compositing Algorithm] set to [Multiply, Gamma Correct]
Parameter [Brightness, Color] set to [Only Brightness]
Parameter [Brightness Retention] set to [Off]
Parameter [Mask Fuzz] set to [1.0 pixels]
Parameter [Airy Disk Radius] set to [50 %]
Parameter [Gamma] set to [0.50]
Parameter [Detail Preservation Radius] set to [20.0 pixels]
Parameter [Saturation] set to [100 %]
Parameter [Strength] set to [44 %]
--- Unified De-Noise
Parameter [Grain Size] set to [22.2 pixels]
Parameter [Walking Noise Size] set to [1.0 pixels]
Parameter [Walking Noise Angle] set to [0]
--- Unified De-Noise
Parameter [Scale 1] set to [99 %]
Parameter [Scale 2] set to [95 %]
Parameter [Scale 3] set to [95 %]
Parameter [Scale 4] set to [95 %]
Parameter [Scale 5] set to [92 %]
Parameter [Equalized Grain] set to [0 %]
Parameter [Scale Correlation] set to [12 %]
Parameter [Color Detail Loss] set to [50 %]
Parameter [Brightness Detail Loss] set to [32 %]
Parameter [Grain Dispersion] set to [22.2 pixels]
File saved [C:\Users\Carles\Downloads\Horse D.jpg].

you can try to replicate it following this. I did not apply Decon at this time since after trying did not see an improvement, but the stars got darken, so canceled it. Skipped also Entropy, since didn't offer me much here. I guess without the need of using Uncalibrated 1 preset in Wipe, it would have preserved more nebulosity and then Entropy could've done more for it.

For less noisy image, in FilmDev, don't push it as much, maybe around 90% or using "Home in" button would be enough.

Regards : )

Carles.

[Matt S]

Hi Carles
Thank you for sharing your log and for your thoughts. To confirm, I am using a 60mm guidescope (with the ASI120MM) and I believe my flats etc are ok.
I’ll try and replicate your workflow with my version of StarTools. My laptop can cope, just about, with v1.5.3, but I wonder if it will struggle with the newer versions like yours.
Thanks again: this is very helpful.
Clear skies
Matt

[Carles]

Hi Matt,

You're welcome

In this cloudynights post, there seems to be the answer
https://www.cloudynights.com/topic/5644 ... artifacts/

It could be the result of internal reflection. I don't know if there's any way of avoiding it... I have an lx50 8"sct but haven't used it much for imaging so don't know.

If thats so, then you should not have the problem with other targets where no bright stars are near try Thor's Helmet or any planetary nebulae

About the StarTools version,. Until recently I was using a 11year old laptop with it, a bit slow but worked..

Since it seems you're imaging at a long focal length, and maybe some oversampling, you can always bin 50% as I did with your image, and with it the file will be smaller so easier to process too

Perhaps the most power hungry module in 1.8 will be HDR.
Give it a try

Carles

[Mike in Rancho]

Hi Matt,

Yeah I'm not sure the flats were working 100% properly myself. In Wipe I did use pretty strong Vignetting settings on this. The 294's are finicky, do you have a good routine down for your calibration? Supposedly they do not like bias, though I have seen a few where that was used (or the dark flats were in the exposure "danger zone") but still corrected okay. If you want you can link a few subs of all types for analysis.

I didn't see the classic 294 amp glow, so I think your darks worked. Just not sure on the flats.

The flare, likely Alnitak, is pretty brutal indeed. I suppose you could take some test shots with a very bright star in field, and perhaps just out of field, and slew the scope around, while watching what happens to any flares. Might be able to track it down by perhaps blocking various things off. When I started using my Newt I soon realized I had to take special care for both lights and flats due to inherent light leaks, and just that once some stray or off-target light gets into the OTA, it can bounce around all over the place and sometimes make its way to the sensor.

Also being a 294MC, I presume you are using a UV-IR cut filter of some type? So many possibilities for reflections and glare. And of course, Alnitak is just the Destroyer of Worlds.

For the atmospheric dispersion on your stars, DSS does have an RGB align setting that can help. There are also techniques in the ST documentation for doing it all in ST layer module too, I believe. To be quick though, I just took your autosave and ran it through DSS again (single frame "stack") with RGB align turned on. It didn't get all of it though. Highlight Repair in Color and Taming in Shrink helped a bit more with the rest.

Here's my stab at it. Thanks for sharing.

Matt S Autosave001 w RGB Align ST8 1A.jpg (496.9 KiB) Viewed 4450 times

[Matt S]

Carles
Thank you again for getting back to me so quickly.
Thanks also for the tips from Cloudy Nights and for upgrading StarTools. It’s been a wee while since I spent any Astro-cash and I sorely tempted to splurge (esp since I see a multitude of boxes from Amazon arrive for my partner’s horse without interruption!).
I’ll reattack my image this week, using your log, and see where it gets me.
Thanks again and clear skies.
Matt

[Matt S]

Dear Mike
Thanks for having a crack at this: what a picture to boot! You and Carles have really helped and I’m grateful for the assistance from this forum. As footnote, I read both Sky at Night and Astronomy Now magazines (UK) and have yet to see a reader’s image quoted as using StarTools..?!? Looks like I’ve just set myself a challenge.
Thank you for the advice. With respect to the flats, you may have hit something here. I use an electric light panel, stuck to a CPC925 dust cover, which I’ve cut a circle out of. This ensures it sits snuggly on the OTA when in use. The exposures for the flats are automatically determined using the ASIAIR Pro. They all, however, show significant vignetting: isn’t this the point, or should they be exposed to show a more uniform coverage of light?
I’m not using any filters at all as I’ve previously read that in StarTools it’s better not to??? Grateful to be told otherwise and I’ll invest. I live under reasonably dark skies, but do have security lights and street lights to contend with. Is there a particular filter that can help with light pollution that is suitable for StarTools and the 294MC Pro (OSC)?
Thanks also for the DSS tips: I’ve not changed my DSS workflow since starting out with a DSLR in 2020. No doubt I can squeeze some more juice from these photons!
Grateful for your thoughts, your time and for the encouragement.
Stay safe and clear skies
Matt

[Carles]

Hi Matt,

as per flats, if they showing vignetting then the main image should do too. when in doubt, try stacking without one of the calibrating frames, you can do this with only few of your sub frames, no need to be all of them (to make things faster.). For instance do a run without Darks, another without Flats and another without Bias.
Then one without calibration frames at all.
Compare the outputs with basic stretching and you see if there is any problem from any of them.

Another thing to consider; do you use any sort of dew-shield on your SCT ? if so, you should take the flats with it on. As the vignetting circle might differ without it.

They all, however, show significant vignetting: isn’t this the point, or should they be exposed to show a more uniform coverage of light?
I’m not using any filters at all as I’ve previously read that in StarTools it’s better not to??? Grateful to be told otherwise and I’ll invest.

Never heard/read anything related....I am using QHY8 L - also an OSC, and typically use Optolong L-pro filter for Broadband as light pollution filter, (i'm at Bortle 7, but would use it on a lower too, for skyglow and so on.. ) and Optolong L-Extreme for NarrowBand (Dual band filter- H-alpha and Oiii) and all my processing is done with StarTools so... no problem if you want to use filters : )

you can check my results here
https://www.instagram.com/juskartes/

I live under reasonably dark skies, but do have security lights and street lights to contend with. Is there a particular filter that can help with light pollution that is suitable for StarTools and the 294MC Pro (OSC)?

a friend of mine has the same 294MCPro, and he also has Lpro and l-enhance and he is also an StarTools user : )

And about the magazine thing...well I don't know. I guess people go mainstream with Pixinsight or APP.

Clear skies : )

Carles.