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can anyone give my lights a quick process please


iwols

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Hi

We allowed our trial of pi expire;) But anyway... Converted to fits and composed in Siril. Just 2 minutes' processing gets us to this, so looking promising as I think the files may have lost something in conversion.

HTH

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Edited by alacant
Translation from es.
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I only do OSC with Pixinsight, so I could be wrong but to me the Masters don't look right. In my images after calibration the Normalised median value is typically about 0.014. In these masters the Lum = 0.446, Red = 0.149; Green = 0.182; & Blue = 0.105.

Also to me it doesn't look like the Flat Calibration is good, as the RGB channels aren't uniform brightness in the corners/edges & there's variation between RGB. i.e. the Red is darker on the right hand edge whilst the Blue/Green are opposite.

The Lum master also has some nasty pixelation (posterisation) in the centre, which I've never seen before.

Would you be able to share a link to the uncalibrated data (or at least a sample)?

Many thanks

Ivor

screengrab1.jpg

screengrab2.jpg

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Hi @iwols

Thanks for sharing the original subs. I'm a bit non-plussed as you've got some good images on your website, so was this a first outing with new kit, or any other change to your usual data acquisition?

Looking at the "FitsHeader" process in Pixinsight I can see that you had 3 sessions on the 24/03, 25/03 & 07/04. The 4 x Lum subs on 24/03 are much brighter than the additional 4 on 07/04 although the noise floor still looks very high to me (0.235). The Sombrero is pretty low in the sky & the images are shot through 2.5 aimasses, so it may be best trying a different (higher) target. (I'd also suggest taking a shorter subs, but more of them, depending on what your light pollution is like)

Arranging the 30 subs in date/time order & viewing with the "Blink" process (with the 'Automatic histogram transformation to all images' selected) it looks like there may have been some cloud or additional light source on some frames? Also I would have thought that you'd have got more detail in the images - although the Sombrero isn't something I can see from our North facing garden, so that's more of a hunch than anything. Another member of the Leeds AS also uses an C8 Edge HD (albeit with a ZWO2600MC PRO) & gets some cracking images. With the Atik 414ex (6.45um) & 1422mm focal length (from "FitsHeader") your resolution (0.94"/px) should be fine.

Did you take any calibration frames (flats for each filter/night) & dark frames? These will be essential to get decent images.

BTW - the posterisation effect in the Master Lum galaxy core is down to the differences between the subs on the two nights. If you just integrate the 4 from the 07/04 that will solve that problem.

I haven't managed to get a decent enough image to share yet, but will have another go...

Cheers
Ivor

 

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Thank you very much Ivor i think youve hit the nail on the head with various comments,im using the c8 edge now for a while instead of my ts optics,which doesnt help and the sombrero was very low just above a bungalow and maybe just below my obsy wall,add that to a few low clouds and my lack of pixinsight skills adds to something im not going to achieve,just done a very quick process with just 3x5 mins worth of subs LRGB with NGC 4565  and got this so dont think my processing is a million miles off(for me anyway)??.Any thoughts?Once again thank you 

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Edited by iwols
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8 hours ago, iwols said:

Any thoughts?

NGC4565 looks a lot better, although I think you could squeeze a bit more out of the image. One tip is to temporarily apply a STF or Auto-boosted STF to check whether there is a colour cast in the image... You can also look at the individual RGB histograms with HT & check that they completely overlap.

I had a quick play with your image, using PixelMath to add small offsets to the RGB channels to align the RGB histograms. Also a rough adjustment of saturation using CurvesTransformation & then another PixelMath expression to flatten out some of the background.

Warren Keller's book "Inside Pixinsight" 2nd edition is worth a look, if you haven't got a copy. It's a bit outdated now, as Pixinsight keeps being improved, but is a good starting point. There's also plenty of youtube videos, albeit of varying quality & I've found Adam Block's Fundamentals worth the ££, so worth looking at his free matierial on youtube.

When processing with Pixinsight, I find it best to work on the Luminance separately to the colour. Typically I stretch the colour data using both ArcSinhStretch & MaskedStretch, and then combine with PixelMath. For the Luminance I use the a series of weak HT stretches.

I've attached a copy of my general workflow.

Cheers
Ivor

sgl_nhg4565.jpg

Pix_Workflow.pdf

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