M42 chronicles
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Please upload large images to photo sharing sites (flickr, etc) rather than trying to upload them as forum attachments.
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Please upload large images to photo sharing sites (flickr, etc) rather than trying to upload them as forum attachments.
Please share the equipment used and if possible camera settings to help others.
Re: M42 chronicles
Yeah, I forgot he mentioned Hyperstar. That does put the camera at the front, which would remove any mount clearance issues. As far as undersampling goes, the Hyperstar can be installed or removed as desired. So it's not like he has a permanent 406.4 mm focal length scope. He can also operate at the full focal length of 2032, and if he gets a .63x reducer/flattener (more money!), he could also operate at 1280 mm.
Re: M42 chronicles
A 2023 Orion effort just before the clocks went forward. Orion sat directly over Manchester City Centre (Bortle 6++) leaving some tricky light gradients to deal with.
Captured with a Canon 7D Mk2 with Super-Tacumar 135mm f3.5 M42 lens (£30 from eBay, £8 for an M42 to EOS adapter)). Celestron AVX mount, unguided.
190x10s lights @ ISO 800. 50 each darks, flats, dark flats. Focus with a small Bahtinov Mask.
Processed twice for practise - Astro Pixel Processor & PixInsight (plenty of satellite trails handled by both programs).
The plan was 30s exposures @ ISO 1600 but the skyglow with the wide field lens was a problem giving an over saturated histogram. Clouds started around frame 200, so 30 of 220 frames were binned by inspection (Blink in PixInsight).
The wide field lens brought a new set of problems. One was the light gradient the other was horizontal banding on the original flats. It turns out that the Adafruit EL panel had an inverter running at 100Hz which synched nicely with my 0.01s flats exposure. Solved by re-taking the flats with an ND8 filter which got the exposures to 0.125s (H/T to Brian @oopfan for resolving that one).
Evaluation - colours in stars, Running Man and Horsehead Nebula (just) with 10s exposures - happy with that at 1st widefield lens attempt. A far cry from the first image I posted on this thread.
Maybe a mosaic including Barnard's Loop next time Orion comes around?
Dave
Captured with a Canon 7D Mk2 with Super-Tacumar 135mm f3.5 M42 lens (£30 from eBay, £8 for an M42 to EOS adapter)). Celestron AVX mount, unguided.
190x10s lights @ ISO 800. 50 each darks, flats, dark flats. Focus with a small Bahtinov Mask.
Processed twice for practise - Astro Pixel Processor & PixInsight (plenty of satellite trails handled by both programs).
The plan was 30s exposures @ ISO 1600 but the skyglow with the wide field lens was a problem giving an over saturated histogram. Clouds started around frame 200, so 30 of 220 frames were binned by inspection (Blink in PixInsight).
The wide field lens brought a new set of problems. One was the light gradient the other was horizontal banding on the original flats. It turns out that the Adafruit EL panel had an inverter running at 100Hz which synched nicely with my 0.01s flats exposure. Solved by re-taking the flats with an ND8 filter which got the exposures to 0.125s (H/T to Brian @oopfan for resolving that one).
Evaluation - colours in stars, Running Man and Horsehead Nebula (just) with 10s exposures - happy with that at 1st widefield lens attempt. A far cry from the first image I posted on this thread.
Maybe a mosaic including Barnard's Loop next time Orion comes around?
Dave
Re: M42 chronicles
Interesting Dave, I enjoyed scanning back to see the evolution there. It is certainly true that every time you change setup it brings new problems and new learning. Part of the reason that I have gone with deep sky narrowfield views of objects thus far is that in some ways it is easier - particularly wrt tilt - flattening etc . where it just doesn't matter so much if you can lose most of the field. Widefield views are nice but technically difficult to get right once you start obsessing about the shapes of stars in the far corners etc. I'm still playing with the refractor making incremental improvements.
So impressive what you have managed there with just a cheap lens and what looks like an enormous amount of sky glow to magic away. I have just switched to a Baader UV/IR cut filter from the ZWO one because it is a bit narrower (blocks outside of 400-700nm) and it did seem to help with colour -i.e. preventing overly blue/ purple around some of the blue/white stars - which now look 'more correct' as judged by comparison with Newt images of the same objects. Anyway quite jealous of you being able to image M42 at all. A big oaktree completely blocks my Southern horizon -- but my daughter has just bought a place with a better aspect south - so maybe next winter. Tim
So impressive what you have managed there with just a cheap lens and what looks like an enormous amount of sky glow to magic away. I have just switched to a Baader UV/IR cut filter from the ZWO one because it is a bit narrower (blocks outside of 400-700nm) and it did seem to help with colour -i.e. preventing overly blue/ purple around some of the blue/white stars - which now look 'more correct' as judged by comparison with Newt images of the same objects. Anyway quite jealous of you being able to image M42 at all. A big oaktree completely blocks my Southern horizon -- but my daughter has just bought a place with a better aspect south - so maybe next winter. Tim
Re: M42 chronicles
Thanks Tim.
I acquired 2 lenses - 135mm f3.5 and 200mm f4 - to experiment with. This seemed a cheaper option than acquiring a 135mm f2 lens which typically costs ~£450. I haven't worried about filters yet but on Astrobin there are many good images produced using UV/IR cut filters with DSLR cameras.
We are in the galaxy season now - one target I have in mind is M81/M82 and to try to capture some IFN. As the year progresses, widefield targets will include such as the Cygnus region, Heart & Soul Nebulae and the Milky Way.
Dave
Cropping can fix that, there is plenty of slack in these very wide field shots.shapes of stars in the far corners etc
I acquired 2 lenses - 135mm f3.5 and 200mm f4 - to experiment with. This seemed a cheaper option than acquiring a 135mm f2 lens which typically costs ~£450. I haven't worried about filters yet but on Astrobin there are many good images produced using UV/IR cut filters with DSLR cameras.
We are in the galaxy season now - one target I have in mind is M81/M82 and to try to capture some IFN. As the year progresses, widefield targets will include such as the Cygnus region, Heart & Soul Nebulae and the Milky Way.
Dave
Re: M42 chronicles
Looking again at post #42. PixInsight 1.8.9-2 build 1601 released 1st March 2024 has a new process called GradientCorrection. A one-click action provided the following improvement to a heavily light pollution affected wide field image of Orion. Note the gradient removal and the improved histogram shape.
Using these defaults
No more having to place sample points for the DynamicBackgroundExtraction process. Time to carry out some re-processing of old data and take advantage of the 20 years of the application's development.
Dave
Using these defaults
No more having to place sample points for the DynamicBackgroundExtraction process. Time to carry out some re-processing of old data and take advantage of the 20 years of the application's development.
Dave
Re: M42 chronicles
M42/NGC1977 - multiple exposure data captured December 2019 and re-processed using PixInsight's High Dynamic Range (HDRComposition) and High Dynamic Range Compression (HDRMT) processes.
Hardware: Celestron CG5 Advanced GT mount, Altair 66ED refractor, 0.8x reducer/flattener, Altair 183C camera.
Software: SharpCap 3.2, PixInsight 1.8.9-2 build 1601.
Data: Lights 50x10s, 30x30s, 30x60s, 15x120s, darks 20 of each exposure, 100 flats, 100 bias.
Outline steps:
Calibration & Integration
Colour calibration of shortest exposure
Create HDR image
HDR mask check
Remove gradients in HDR image
Perform background neutralisation
Delinearise image
Create Lightness mask using ChannelExtraction
Apply Dynamic Range Compression
Lightness mask and CurvesTransformation to adjust highlights contrast
Lightness mask and CurvesTransformation to adjust shadows contrast
Learning resources
The new colour calibration tool, SPCC, requires an astrometric solution in the image data. To do this I had to get the PixInsight Image Resolver working as the data had no RA/DEC information. This required download of the Gaia files for Image Resolver and SPCC (~120Gb).
Also to tidy up some FITS header anomolies from the SharpCap 3.2 version I used the PixInsight script BatchFITSKeywordEdit to bulk edit BAYERPAT & COLORTYP and remove BAYEROFFX & BAYEROFFY in 325 images (lights, darks, flats, bias).
Use of these PixInsight High Dynamic Range processes now gives scope for being able to handle longer M42 exposures than I have previously attempted.
Dave
Hardware: Celestron CG5 Advanced GT mount, Altair 66ED refractor, 0.8x reducer/flattener, Altair 183C camera.
Software: SharpCap 3.2, PixInsight 1.8.9-2 build 1601.
Data: Lights 50x10s, 30x30s, 30x60s, 15x120s, darks 20 of each exposure, 100 flats, 100 bias.
Outline steps:
- Use WeightedBatchPreprocessing (WBPP) script to calibrate and integrate the 4 data sets.
- Colour calibration of the short exposure (10s) image with Spectrophotometry Colour Calibration (SPCC).
- Combine 4 images into HDR image using HDRComposition.
- Check HDR mask covers washed out region of highest exposure image (120s).
- Remove gradients with GradientCorrection process.
- Perform background neutralisation with BackgroundNeutralization process.
- Delinearise image with Screen Transfer Function and HistogramTransformation.
- Use ChannelExtraction to create lightness mask.
- Apply dynamic range compression with HDRMT.
- Use lightness mask with CurvesTransformation to adjust contrast of highlights.
- Use lightness mask inverted with CurvesTransformation to adjust contrast of shadows.
- Crop to taste.
Calibration & Integration
Colour calibration of shortest exposure
Create HDR image
HDR mask check
Remove gradients in HDR image
Perform background neutralisation
Delinearise image
Create Lightness mask using ChannelExtraction
Apply Dynamic Range Compression
Lightness mask and CurvesTransformation to adjust highlights contrast
Lightness mask and CurvesTransformation to adjust shadows contrast
Learning resources
- Dynamic Range Management https://www.youtube.com/watch?v=LdCm9Ack8KI
- pixinsight.com Knowledge capsules - Dynamic range (requires login)
The new colour calibration tool, SPCC, requires an astrometric solution in the image data. To do this I had to get the PixInsight Image Resolver working as the data had no RA/DEC information. This required download of the Gaia files for Image Resolver and SPCC (~120Gb).
Also to tidy up some FITS header anomolies from the SharpCap 3.2 version I used the PixInsight script BatchFITSKeywordEdit to bulk edit BAYERPAT & COLORTYP and remove BAYEROFFX & BAYEROFFY in 325 images (lights, darks, flats, bias).
Use of these PixInsight High Dynamic Range processes now gives scope for being able to handle longer M42 exposures than I have previously attempted.
Dave
Re: M42 chronicles
Hi Dave,
Thanks for the great write-up! I have a question. Let me repeat your Lights exposure times. You wrote:
Data: Lights 50x10s, 30x30s, 30x60s, 15x120s
When I convert to Integration Time, I get:
Data: Lights 500s, 900s, 1800s, 1800s
IMO, you won't gain much faint nebula by moving up to 240s exposure. I'd recommend increasing the size of the 120s stack until you achieve 30x120s.
EDIT: My reasoning is that your Bortle 6 skies won't benefit from longer and longer exposure times, but you will benefit from longer Integration Times.
Brian
Thanks for the great write-up! I have a question. Let me repeat your Lights exposure times. You wrote:
Data: Lights 50x10s, 30x30s, 30x60s, 15x120s
When I convert to Integration Time, I get:
Data: Lights 500s, 900s, 1800s, 1800s
IMO, you won't gain much faint nebula by moving up to 240s exposure. I'd recommend increasing the size of the 120s stack until you achieve 30x120s.
EDIT: My reasoning is that your Bortle 6 skies won't benefit from longer and longer exposure times, but you will benefit from longer Integration Times.
Brian
Re: M42 chronicles
Brian
Thanks for the comments. I agree with you that Bortle 6 brings its limits for longer exposures. I will try for a larger integration time with 120s exposures. The AVX mount I have now will cope better than the CG5 did. It might be too late in the year now as Orion heads towards the Manchester soup in the west. I need to find a suitable lower exposure time - maybe 30s? I feel a 2 image HDR solution might give better results. I suppose it will be an experiment to find suitable values.
There was a time when I thought 120s would be unrealistic for M42 but now, with the right tools, anything is possible.
Dave
Thanks for the comments. I agree with you that Bortle 6 brings its limits for longer exposures. I will try for a larger integration time with 120s exposures. The AVX mount I have now will cope better than the CG5 did. It might be too late in the year now as Orion heads towards the Manchester soup in the west. I need to find a suitable lower exposure time - maybe 30s? I feel a 2 image HDR solution might give better results. I suppose it will be an experiment to find suitable values.
There was a time when I thought 120s would be unrealistic for M42 but now, with the right tools, anything is possible.
Dave
Re: M42 chronicles
Dave,
Yes, too short of an exposure brings its own set of problems. I think you are good with 3 stacks: 30s, 60s, and 120s. Then just concentrate on reducing noise by increasing Integration Time like 50x30s, 50x60s, and 50x120s.
Brian
Yes, too short of an exposure brings its own set of problems. I think you are good with 3 stacks: 30s, 60s, and 120s. Then just concentrate on reducing noise by increasing Integration Time like 50x30s, 50x60s, and 50x120s.
Brian
Re: M42 chronicles
Dave,
Thanks for all the processing details. If I do anything good enough in the next few weeks I'll record the same - there are just so many alternatives now. I like the whole concept of keeping a chronicle of some object or another because it is easy to lose sight of just how far and how rapidly things change. Just looking back at some of galaxy pictures -- the 2023 and 2024 versions are just so much better than 21 and 22 - partly it's increased skill at acquisition and at using sharpcap at the front end but it is also largely down to the software --especially the gradient tool and the RC Blur Xt and Noise Xt tools, The main problem has been the awful weather which has limited me to just the odd hour here and there.
Tim
Thanks for all the processing details. If I do anything good enough in the next few weeks I'll record the same - there are just so many alternatives now. I like the whole concept of keeping a chronicle of some object or another because it is easy to lose sight of just how far and how rapidly things change. Just looking back at some of galaxy pictures -- the 2023 and 2024 versions are just so much better than 21 and 22 - partly it's increased skill at acquisition and at using sharpcap at the front end but it is also largely down to the software --especially the gradient tool and the RC Blur Xt and Noise Xt tools, The main problem has been the awful weather which has limited me to just the odd hour here and there.
Tim