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geoflewis

M100 LRGB - 11.5 hours in 4 nights of variable transparancy

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Having seen a few versions of M100 pop up on here the last couple of days, I thought I'd throw mine in the mix. At 11.5 hours it's just a tad more than Olly collected with his dual rig in one night (I wish), but it took me 4 nights of varaible seeing & transparancy. Captured with my QSI583wsg + Astronomic Type 2 LRGB filters through my C14XLT with x0.63 Optec Telecompressor, for an effective ~F7.

I'm still learing how to combine LRGB, so will be interested in feedback from those that know better than me. There is still some vignetting showing in the right hand corners, so mabe I should crop those out, but anyway here it is....

M100_LRGB_IP_PS.thumb.jpg.dfb564848463b3906855fb5fa7cb8776.jpg

Thanks for looking,

Geof

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11 minutes ago, des anderson said:

A stunning image, you`ve got to be proud that. Des

Thanks Des, yes, I'm pretty pleased with it, though I'm sure someone with better processing skills than me could get a better end result. Cheers, Geof

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Nice, Im with you on the L rgb combination. Cant seem to get the L side to work for me at all.

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20 minutes ago, simmo39 said:

Nice, Im with you on the L rgb combination. Cant seem to get the L side to work for me at all.

Thanks Simmo39,

I feel as if I'm making progress with LRGB, but I get very inconsistent results. I find that the L can definitely overwhelm the RGB, so I have to back that off in the combination.I also have issues with varying star sizes when seeing and/or transparancy is variable over several nights. Certainly combining the 4 channels has become much easier since I started using Registar to aligning and pad/crop the stacked images, before combining them.

Whereabouts in Norfolk are you, I'm in south Norfolk?

Cheers, Geof

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Hi Geof, Im in Sunny Swaffham. I have been playing with the data for a while and like you said i get inconsistent results. I will have another play later but I hadnt considered variable seeing or transparancy. There may be some of my problem too.

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Not so far away then...., I would be happy to get together some time to exchange ideas if you're up for that - perhaps send me a PM....

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Just now, geoflewis said:

Not so far away then...., I would be happy to get together some time to exchange ideas if you're up for that - perhaps send me a PM....

Yep sounds good.

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Looking like you may have some really nice data but I can't help but notice the galaxy has an unusual appearance, almost as if it's through stained glass window? Perhaps some of the processing steps have been a little too harshly applied?

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36 minutes ago, Shibby said:

Looking like you may have some really nice data but I can't help but notice the galaxy has an unusual appearance, almost as if it's through stained glass window? Perhaps some of the processing steps have been a little too harshly applied?

Hi Shibby, I think I understand what you are saying, as I too see that 'stained glass window' effect. I've been back and forth with the sharpening of the L data, so I'm wondering whether that has been overdone. As I mentioned above I'm still learning the ropes of LRGB processing, but it's still very much a trial and error (with I fear too much error) process. Maybe I should revisit the data and see if I can improve the image. Thanks for the feedback, Geof

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Good stuff Geof, you're way ahead of me I haven't even started processing mine :grin:

Nice PS tutorial here that I use for galaxies but I still get in a muddle hopping back and forth with star masks etc.

Dave

https://www.youtube.com/watch?v=2lozs1yu014

 

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1 minute ago, Davey-T said:

Good stuff Geof, you're way ahead of me I haven't even started processing mine :grin:

Nice PS tutorial here that I use for galaxies but I still get in a muddle hopping back and forth with star masks etc.

Dave

https://www.youtube.com/watch?v=2lozs1yu014

 

Thanks Dave, I'll definitely check out the tutorial later. I'm somewhat a novice using PS, but the software I do use, ImagesPlus (IP), operates in a similar way, so I may be able to apply the methods, or even switch to using more of PS tools. Unfortunately there isn't a very large population of IP users, most of whom seem to be DSLR/OSC camera users, which is how I started out. Hence, finding useful IP tutorials for mono CCD LRGB is something of a challenge, so I'm largely self taught. I keep looking longingly at Pixinsight and APP, but hesitate to jump from one deep dark AP pool to another, as drowning in either will probably kill me.....?

Cheers, Geof

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4 hours ago, geoflewis said:

Thanks Simmo39,

I feel as if I'm making progress with LRGB, but I get very inconsistent results. I find that the L can definitely overwhelm the RGB, so I have to back that off in the combination.I also have issues with varying star sizes when seeing and/or transparancy is variable over several nights. Certainly combining the 4 channels has become much easier since I started using Registar to aligning and pad/crop the stacked images, before combining them.

Whereabouts in Norfolk are you, I'm in south Norfolk?

Cheers, Geof

Very nice image!

Different star sizes could also be focus? I noticed that with my 8" SCT, I have to readjust focus about half way through the night, otherwise stars beginning to look bigger and bigger...

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44 minutes ago, geoflewis said:

Hi Shibby, I think I understand what you are saying, as I too see that 'stained glass window' effect. I've been back and forth with the sharpening of the L data, so I'm wondering whether that has been overdone. As I mentioned above I'm still learning the ropes of LRGB processing, but it's still very much a trial and error (with I fear too much error) process. Maybe I should revisit the data and see if I can improve the image. Thanks for the feedback, Geof

Could be stacking (do you use DSS?) there is one setting that used to give me doughnut-like stars, I forgot what it was...Could also be partly focus or star alignment (when you add luminance, or if you do different binning). Hopefully someone more experienced will be able to help.

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17 minutes ago, Galaxyfaraway said:

Very nice image!

Different star sizes could also be focus? I noticed that with my 8" SCT, I have to readjust focus about half way through the night, otherwise stars beginning to look bigger and bigger...

 

14 minutes ago, Galaxyfaraway said:

Could be stacking (do you use DSS?) there is one setting that used to give me doughnut-like stars, I forgot what it was...Could also be partly focus or star alignment (when you add luminance, or if you do different binning). Hopefully someone more experienced will be able to help.

Thanks yes, all of the above might contribute ?. Binning 2x2 was the same for all filters as without binning the scope/camera would be over sampled except in excellent seeing, even with the x0.63 telecompressor in train. I autofocus on filter change and monitor HFR as reported by SGP so other than the 4 hours of L shot one night the fairly frequent auto focus routine (~1 hour intervals for RGB) should keep the stars reasonably tight. However, what I do see during poor transparancy is that the Blue filter stars and sometimes the Green stars come out larger FWHM. I don't use DSS, but ImagesPlus and I now use Registar for channel alignment which has significantly improved the channel combination. The C14XLT is old school so suffers from coma, which is just another hurdle in the processing mix to overcome, though the Optec telecompressor lens does a pretty good job with that. I think the main issues are with the processing operator....!! ?

Cheers, Geof

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