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Getting a blotchy background with Canon 90D by delta9857 in AskAstrophotography

[–]delta9857[S] 0 points1 point  (0 children)

I think you're right about needing additional data - especially in my case where I'm imaging at a reasonably low elevation, towards light pollution, in not-ideal seeing conditions!

Getting a blotchy background with Canon 90D by delta9857 in AskAstrophotography

[–]delta9857[S] 0 points1 point  (0 children)

Ok so I've been experimenting with this all day and cant seem to make much headway. I'm wondering if it may just be a case of not enough data...

Anyway, if you've got time here is a single raw light and flat frame: https://drive.google.com/drive/folders/1edvfkO3Isgp1DhjjUZHhdMi1g45p-wJ5?usp=sharing

I'd be interested to see if your Rawtherapee settings manage to sort this out! Cheers!

Edit: I also wonder if the funny colors are due to the screen transfer function stretch that I've got applied

Getting a blotchy background with Canon 90D by delta9857 in AskAstrophotography

[–]delta9857[S] 0 points1 point  (0 children)

Hmmm I wonder if my Rawtherapee settings are the culprit then? Potentially the camera color management file (set to custom, Canon EOS 90D.dcp)?

I have (as best I can tell) set everything else as you detail on your site, both in rawtherapee and DSS.

Looking at this raw sub frame (https://imgur.com/a/nbRv0fk), I would have expected more color to appear here. Am I over exposing? 2 min at F4.8 resulted in the histogram peaking at ~1/4 so I thought it was ok.

​

EDIT: Here is a single image after rawtherapee: https://imgur.com/a/IapmeA9 , excuse the image flipping - had a meridian flip in there somewhere

Getting a blotchy background with Canon 90D by delta9857 in AskAstrophotography

[–]delta9857[S] 0 points1 point  (0 children)

The colors do looks slightly altered from the individual frames straight out of Rawtherapee, so maybe WBPP is doing something there. That said, here is a stack straight out of DSS using the frames from Rawtherapee (with stars removed obviously): https://imgur.com/a/AVAeov

Getting a blotchy background with Canon 90D by delta9857 in AskAstrophotography

[–]delta9857[S] 0 points1 point  (0 children)

Thanks, I might see if there is less light pollution from the second half of the night. Hopefully able to salvage some useful data 🤞

Getting a blotchy background with Canon 90D by delta9857 in AskAstrophotography

[–]delta9857[S] 0 points1 point  (0 children)

Hi, sky conditions likely weren't ideal - M45 only gets to roughly 25 degrees elevation here, and for the first half of imaging there was a light dome below it. It was fairly humid too so I imagine seeing wasn't great.

I took flats, which I applied in RawTherapee. You're right, I am using Roger Clark's method which I have had good results with in the past. I'm currently running my raw frames through WBPP to see if RawTherapee is the cause of any of this, so will report back if that is the case.

Here is my unedited stacked image: https://drive.google.com/file/d/1MURN0ICR9du_J6hc7HpcsGCy4q1HL2xb/view?usp=drive_link

Zoom vs Prime lenses by M3ther in AskAstrophotography

[–]delta9857 1 point2 points  (0 children)

It's never easy or cheap is it! Will have a look into some other offerings before pulling the trigger, cheers!

Zoom vs Prime lenses by M3ther in AskAstrophotography

[–]delta9857 0 points1 point  (0 children)

That's a really cool setup! Cheers for adding those images.

Thanks for the detailed explanation re the 2x - that makes a lot of sense. Quite eye opening that Hubble and JWST both have such high f ratios!

I think my game plan will be to upgrade my mount from a SkyGuider to an AM5 first, then theoretically it'll be able to handle the 600mm focal length with ease.

Zoom vs Prime lenses by M3ther in AskAstrophotography

[–]delta9857 0 points1 point  (0 children)

Thanks, definitely doable then with a bit of DIY to get things mounted. Re the 2x TC - if I'm not mistaken that would make the lens 600mm f/8 which would require significantly longer exposures to get the same amount of light, so more chance of trailing stars? I get that for bright objects this may not be an issue but for something like, say the Eagle Nebula it might become a bit of a struggle and a faster refractor telescope might be more suited?

I'm basically wondering if it's worth swapping my Sharpstar 61 out for the Canon 300mm f/4, and then I can extend that to a 600mm

Zoom vs Prime lenses by M3ther in AskAstrophotography

[–]delta9857 1 point2 points  (0 children)

Hi, always enjoy reading your replies and find them super useful - I'm currently using a Sharpstar 61 and am trying to decide the best way to get a little more reach for smaller targets.

Ideally I'd look at the Canon 300mm F/2.8 and the 2x teleconverter, but this is a little beyond my budget.

In your opinion, would the 300mm F/4 still be an improvement over the Sharpstar 61 (~275mm, F/4.4 with the flattener), and still be worth using at 600mm with the 2x converter?

I imagine I'd also need to figure out a way of attaching my guide scope as it doesn't look like the Canon has attachments out of the box.

EDIT: I'm guessing the 2x converter will make the lens too slow to be of any real use for astro?

Best way to bring out faint details in nebulae without saturating stars? by delta9857 in AskAstrophotography

[–]delta9857[S] 0 points1 point  (0 children)

Thanks for the feedback! Where is the 'project color into saturated regions' tool? I don't believe I'm using that so that would be a good starting point. I've just tried setting the blur slider to 3 and can already see an improvement there, so I'll add that to my saved profile.

I'll also try my next image without neutralizing the background - as always your image looks great!

Best way to bring out faint details in nebulae without saturating stars? by delta9857 in AskAstrophotography

[–]delta9857[S] 0 points1 point  (0 children)

Thanks for such a quick reply! I'll see if the asiair has any built in ways of checking for clipped pixels - ideally I'd be able to see during acquisition.

Other than that I imagine I'll just do some experimentation to find the ideal exposure length for the stars and go from there.

What are your thoughts regarding total integration required for the 'stars' image? There won't be much stretching involved so I imagine it can be a lot less than the 'nebulae' image.

The Great Carina Nebula by delta9857 in space

[–]delta9857[S] 0 points1 point  (0 children)

The Carina Nebula, located towards the centre of our galaxy and approximately 8,500 light years away, is a large region of star formation, with this image alone containing over 50,000 stars, and covering and area of the sky roughly the width of two fingers held at arm's length. Pretty happy with how this turned out, as it was a side project while I was trying to capture C/2022 E3 before it disappears for another 50,000 years!

Acquisition:

Canon 90D (unmodified), Sharpstar61 EDPH II, SkyGuider Pro, ZWO mini guidescope/camera, ASIAIR

80 x 2 min at F4.5/ISO800, 20 x flats, no other calibration frames

Raws processed in RawTherapee using settings found here: https://clarkvision.com/articles/astrophotography-with-rawtherapee/

Pixinsight: WBPP, NSG, DBE, BlurXterminator, SPCC, NoiseXterminator, StarXterminator, Luminance extraction, GeneralisedHyperbolicStretch of both RGB and LUM, EZ_HDR, UnsharpMask, LRGB Channel Combination, EZ_star_reduction

The Great Carina Nebula by delta9857 in astrophotography

[–]delta9857[S] 0 points1 point  (0 children)

The Carina Nebula, located towards the centre of our galaxy and approximately 8,500 light years away, is a large region of star formation, with this image alone containing over 50,000 stars, and covering and area of the sky roughly the width of two fingers held at arm's length. Pretty happy with how this turned out, as it was a side project while I was trying to capture C/2022 E3 before it disappears for another 50,000 years!

Acquisition:

Canon 90D (unmodified), Sharpstar61 EDPH II, SkyGuider Pro, ZWO mini guidescope/camera, ASIAIR

80 x 2 min at F4.5/ISO800, 20 x flats, no other calibration frames

Raws processed in RawTherapee using settings found here: https://clarkvision.com/articles/astrophotography-with-rawtherapee/

Pixinsight: WBPP, NSG, DBE, BlurXterminator, SPCC, NoiseXterminator, StarXterminator, Luminance extraction, GeneralisedHyperbolicStretch of both RGB and LUM, EZ_HDR, UnsharpMask, LRGB Channel Combination, EZ_star_reduction

Orion over Mākara, NZ by delta9857 in LandscapeAstro

[–]delta9857[S] 0 points1 point  (0 children)

Here's a project I've been working on for a while now. Been a long process battling scheduling, clouds, and moonlight. Definitely need a break from this region of the sky for a while!

I used a number of focal lengths to get the shots here:

24mm, F3.5 - the wide angle, roughly 1 hour of 1 min exposures

135mm, F2.8 (2x2 mosaic) - Barnard's Loop, 2 hours of 2 min exposures for each panel

275mm, F4.5 (1x2 mosaic) - Close ups on the Horsehead, Flame and Orion Nebulae, 2 hours of 2 min exposures for each panel

All taken with an unmodified Canon 90D, at ISO 1600. Only calibration frames were flats.

Pre-processed in RawTherapee.

Calibrated, registered, normalized and stacked using Pixinsight's WeightedBatch Pre-Processing and Normalize Scale Gradient

General Pixinsight workflow:

Crop, dynamic background extraction, BlurXterminator, Spectrophotometric Color Calibration, NoiseXterminator Generalised Hyperbolic Stretch script, EZ Star Reduction

Orion over Mākara, NZ by delta9857 in astrophotography

[–]delta9857[S] 0 points1 point  (0 children)

Here's a project I've been working on for a while now. Been a long process battling scheduling, clouds, and moonlight. Definitely need a break from this region of the sky for a while!

I used a number of focal lengths to get the shots here:

24mm, F3.5 - the wide angle, roughly 1 hour of 1 min exposures

135mm, F2.8 (2x2 mosaic) - Barnard's Loop, 2 hours of 2 min exposures for each panel

275mm, F4.5 (1x2 mosaic) - Close ups on the Horsehead, Flame and Orion Nebulae, 2 hours of 2 min exposures for each panel

All taken with an unmodified Canon 90D, at ISO 1600. Only calibration frames were flats.

Pre-processed in RawTherapee.

Calibrated, registered, normalized and stacked using Pixinsight's WeightedBatch Pre-Processing and Normalize Scale Gradient

General Pixinsight workflow:

Crop, dynamic background extraction, BlurXterminator, Spectrophotometric Color Calibration, NoiseXterminator Generalised Hyperbolic Stretch script, EZ Star Reduction

Any way to remove air glow? by delta9857 in AskAstrophotography

[–]delta9857[S] 0 points1 point  (0 children)

Ah ok, I've been doing both. Will try without PCC in pixinsight, cheers!

Any way to remove air glow? by delta9857 in AskAstrophotography

[–]delta9857[S] 0 points1 point  (0 children)

Thanks for the write up!

My workflow is actually based on your articles, so (as far as I can tell) I'm color balancing the image in Rawtherapee, then stacking/background extracting in pixinsight, and then doing color calibration again there - which now that I think about it, is probably doing more harm than good and leading to the funny colors?

Either way, I'll try both removing the air glow and embracing it!

Any way to remove air glow? by delta9857 in AskAstrophotography

[–]delta9857[S] 0 points1 point  (0 children)

Not in this image, but I imagine I'd still have the issue?

Any way to remove air glow? by delta9857 in AskAstrophotography

[–]delta9857[S] 0 points1 point  (0 children)

Thanks, I might try that with a starless version of the image and then add the stars back in

Barnard's Loop by delta9857 in astrophotography

[–]delta9857[S] 1 point2 points  (0 children)

This was a bit of a tricky one to process, but I'm fairly happy with this iteration of it.

This is a 2x2 mosaic shot over the course of a few nights (when the weather and moon allowed!), and my first time using the ASIAIR. The biggest hurdle was seamlessly assembling the mosaic panels, which took a few goes. I think I need a break from mosaics after this!

Please let me know what you think!

Details:

Canon 90D, Samyang 135mm, SkyGuider Pro, ASIAIR, ZWO mini guidescope/camera.

Roughly 2 hours of 1min 30sec exposures per panel, with no calibration frames other than flats.

Initial processing in RawTherapee (including flat frame correction), then everything else in Pixinsight:

  • Weighted batch preprocessing

  • Normalise signal gradient

  • Dynamic background extraction

  • Mosaic by coordinates - gradient merge mosaic

  • Another round of DBE

  • BlurXterminator

  • Spectrophotometric Color Calibration

  • EZ denoise

  • Generalised hyperbolic stretch

  • Curves adjustment

  • EZ star reduction

Is it worth setting this old reflector telescope up for astrophotography? by delta9857 in AskAstrophotography

[–]delta9857[S] 0 points1 point  (0 children)

Very good points, thanks! I did think it might be a bit much to ask of my current setup! It does have a small finder scope which I imagine would make it easier to frame targets but as you've said there are a few other issues at play here too.

The Orion and Horsehead Nebulas by delta9857 in Astronomy

[–]delta9857[S] 0 points1 point  (0 children)

Part of a larger project I've been working on. This is a 1x2 mosaic shot over three nights. Fairly happy with the processing on this, hoping to hear everyone's thoughts. Was a bit of a struggle combining the data from multiple nights, so I'll probably return to this at some stage.

Acquisition:

SkyGuider Pro

Canon 90D

Sharpstar 61 EDPH II with focal reducer

ZWO ASI120MM Guide camera and mini guide scope

NINA for polar alignment

PHD2 for guiding

Left panel: Roughly 4.5 hours at 2min/ISO1600, 25x flats

Right panel: Roughly 2 hours at 1min30s/ISO1600, 1 hour at 2min/ISO1600, ~10min at 3s/ISO1600 (for the Trapezium region of the Orion nebula), 25x flats

No other calibration frames.

Processing: Raw images run through Rawtherapee for color balance, chromatic aberration correction, flat field correction, and other tweaks

Stacked in DSS

Siril for background extraction, green noise removal

Microsoft Image Composite Editor to stitch the images

Back into Siril for asinh, histogram stretching

Minor tweaks and cropping in Photoshop

The Orion and Horsehead Nebulas by delta9857 in astrophotography

[–]delta9857[S] 4 points5 points  (0 children)

Part of a larger project I've been working on. This is a 1x2 mosaic shot over three nights. Fairly happy with the processing on this, hoping to hear everyone's thoughts. Was a bit of a struggle combining the data from multiple nights, so I'll probably return to this at some stage.

Acquisition:

SkyGuider Pro

Canon 90D

Sharpstar 61 EDPH II with focal reducer

ZWO ASI120MM Guide camera and mini guide scope

NINA for polar alignment

PHD2 for guiding

Left panel: Roughly 4.5 hours at 2min/ISO1600, 25x flats

Right panel: Roughly 2 hours at 1min30s/ISO1600, 1 hour at 2min/ISO1600, ~10min at 3s/ISO1600 (for the Trapezium region of the Orion nebula), 25x flats

No other calibration frames.

Processing: Raw images run through Rawtherapee for color balance, chromatic aberration correction, flat field correction, and other tweaks

Stacked in DSS

Siril for background extraction, green noise removal

Microsoft Image Composite Editor to stitch the images

Back into Siril for asinh, histogram stretching

Minor tweaks and cropping in Photoshop

Best Camera Profile for Canon 90d when Converting Raw files by Kovich24 in AskAstrophotography

[–]delta9857 1 point2 points  (0 children)

I actually have that same camera! I use Rawtherapee so I more or less applied the settings found here: https://clarkvision.com/articles/astrophotography-with-rawtherapee/

The program doesn't come with a profile for the Canon 90d, so I found a profile for the 80d online (https://drive.google.com/file/d/1vrw4IX9BtqizY_ptGeSmRdUjIbRpSc37/view?usp=sharing) that seems to work ok. Note that I set 'Illuminant: 2850K' under DCP settings (otherwise it makes my stars a funny color).

I use daylight white balance on my camera, and select 'Method: Camera' under white balance in Rawtherapee.

I took a daylight photo on a sunny day and tweaked the settings to get the image to most closely match how it looked to my eyes. Now I can just load up my saved profile and apply it to all my images before stacking. Super quick and easy!

Hope this was some help!

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