StarTools

The image attached has an area of streaked colour, it could have been caused by the oag cutting across the corner of the processor, it seemed a little loose when i disassembled it. I would like to know if anything can be done with it.

Ivo (or anyone) this is my first effort with my own data, I would appreciate it if you could process it and show me what can be done. Please tell me how I can post the data!

For info.

SW 72ed Pro .85 corrector. ZWO ASI183 MC Pro. 290MM Mini oag camera. APT 45 x 60 seconds (didn't have a lot of time). Flats, Flat Darks and Darks. Bortle 3 zone.

Thanks

David

Hi David,

Please feel free to share a link to the dataset via Dropbox, Google Drive or similar.

The dataset looks quite nice and clean (e.g. well calibrated) except for those pesky streaks! Those streaks are quite peculiar. As a guess they appear to follow the celestial rotation, which may indicate an issue with your calibration frames.
Do they still show up if you stack without any calibration frames?

Ivo

Yes, the streaks were there when I did a stack without the calibration frames. I then re-stacked with them and without the lowest scoring frames. The streaks coincided with the position of the edge of the oag prism when I took down the equipment, i.e diagonally across the corner.

I will use dropbox later today.

Cheers

David

https://www.dropbox.com/s/bqpwkf8xx72vf ... 3.fit?dl=0

Dropbox link to data

M42, solved by cropping....I took the easy way out.

Hi David,

Apologies - I completely forgot to reply to you!
You already did a fine job and other than the streaks your dataset is really nice, clean and well calibrated. Great stuff!

A couple of things to look out for; the dataset seem to be already color balanced, which seems odd as it is from an OSC. Any idea how this might have happened? The dataset also seems to have aberrant coloring information in the hihglights. The default Color Constancy mode in the Color module will not work that well as a result. You can use the Highlight Repair parameter in 1.6 to fix up some of the star cores, but I chose the "legacy" preset instead.

Use the MaxRGB mode to check for spurious green dominance; your image has a lot of green. M42 is one of the rare objects that actually shows some green dominance in its core, but other than that green dominance is rare. Finally, you can use the Filter module's Fringe Killer mode to kill that unsightly chromatic aberration.

Other than that you've managed great detail. And, indeed, cropping is the way to go here
Processed in 1.6.386 beta;
FWIW, my log;
--- Bin
Parameter [Scale] set to [(scale/noise reduction 35.38%)/(798.89%)/(+3.00 bits)]
Image size is 1944 x 1299
--- Auto Develop
To see what we got.
--- Crop
Getting rid of stacking artifacts.
Parameter [X1] set to [27 pixels]
Parameter [Y1] set to [22 pixels]
Parameter [X2] set to [1920 pixels (-24)]
Parameter [Y2] set to [1278 pixels (-21)]
Image size is 1893 x 1256
--- Wipe
Getting rid of light pollution.
Parameter [Dark Anomaly Filter] set to [5 pixels] (just in case, probably not needed)
--- Auto Develop
Final global stretch.
Parameter [Ignore Fine Detail <] set to [4.2 pixels] to make AutoDev ignore background noise.
--- Deconvolution
Auto-generate a conservative mask (this still selects M42's core as opposed to the regular auto-mask).
Parameter [Radius] set to [1.8 pixels]
Parameter [Iterations] set to [11]
Parameter [Regularization] set to [0.88 (noisier, extra detail)]
--- SNR-aware Wavelet Sharpening
Created inverse star mask.(e.g. deselecting anything that is a star, having some small structural detail caught up is not a problem)
This is so stars don't get emphasised any further.
Parameter [Amount] set to [844 %]
Parameter [High SNR Size Bias] set to [89 %]
--- Color
Legacy preset
Parameter [Saturation Amount] set to [387 %]
Parameter [Green Bias Reduce] set to [1.34]
Parameter [Highlight Repair] set to [5 pixels]
--- Psycho-Visual Grain Equalization De-Noise
Switching Tracking off and choosing Denoise 2
Parameter [Grain Size] set to [11.6 pixels]
Parameter [Grain Removal] set to [60 %]
--- Filter
Put offending stars in star mask.
Parameter [Filter Mode] set to [Fringe Killer]
Click on the aberrant color until it disappears.

Apologies again for the late response - hope this still helps!

Ivo

Nicely processed, I have some way to go with processing.

As for the colour balancing; I used the smart histogram process in Sharpcap Pro then worked with APT to capture the images. Stacking was done with DSS 4.2.2. What setting would cause colour balancing? Would the colouring information in highlights be the same issue.

I presume the CA is something I have to live with, my 72ed /corrector are not exactly high end.

thanks

David

Topographic wrote:Ivo

Nicely processed, I have some way to go with processing.

Honestly, detail("luminance")-wise your processing was just fine! It's just the coloring that's a bit different between your and my version.

Stacking was done with DSS 4.2.2. What setting would cause colour balancing? Would the colouring information in highlights be the same issue.

The latest beta should have an option that lets you turn off white balancing altogether (which then allows you to use the second option when importing your dataset, yielding a small fidleity boost). The highlight coloring issue is very likely related to the color balancing.

I presume the CA is something I have to live with, my 72ed /corrector are not exactly high end.

It's nothing major and the Fringe Killer mode in the Filter module goes a long way. Just something to be mindful of. And if you ever go narrowband, it's not an issue at all!

Cheers!

Ivo

For information I tracked down the source of the streaks, they are reflection artifacts from Rigel, reflected in the Skywatcher flattener!

Topographic wrote:Ivo

For information I tracked down the source of the streaks, they are reflection artifacts from Rigel, reflected in the Skywatcher flattener!

Really appreciate the follow-up! It's one of those things I certainly never would have guessed!