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#1 rflinn68

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Posted 10 September 2013 - 03:51 AM

This was the last of my 3 targets from Saturday night. 5 minutes at f/4 can sure leave some wild halos on the bright stars. I guess I need to image it again some night with some shorter subs and try an image overlay or something? Any other ideas? I wanted to stretch it some more but the halos would just get even crazier. Bumping up curves sure did make the nebula pop but I had to back it back down. :(

Anyway, this is 23X300sec at ISO 800 with the AT8IN.

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#2 Wouter D'hoye

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Posted 10 September 2013 - 05:32 AM

Well.. looking at the small picture I was like, wow.; this is something.. but when I looked at the full size image I have to say something must have gone quite wrong with the processing. Did you use some sort of very aggressive noise reduction? Or was 8bit data used instead of 16bit? This image has a lot going for it and it appears to have excellent data. But the colours look stepped without smooth transitions. Very odd. I'm sure a lot better can come from such data.

Kind regards,

Wouter.

#3 Jeff2011

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Posted 10 September 2013 - 10:54 AM

Richard,

I really like the detail in the reflection nebulas. However, the halos kind of remind me of a collimation star test.

#4 CounterWeight

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Posted 10 September 2013 - 03:54 PM

Agree - something in the processing really went at the data pretty aggressively. Those are some bright stars and faint cotton candy... recipe for a great image. Can you go over your processing steps? maybe we can help or suggest something. Agree there looks like great data there but hard to tell.

#5 rflinn68

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Posted 10 September 2013 - 05:15 PM

All I've been doing lately is do an initial stretch with a few levels adjustments, then duplicate the image and convert it to greyscale as a luminosity layer, duplicate the layer again and do a Screen Mask Invert, then run the Block Method to saturate the final image. After that I will go into StarTools with it for some final adjustments.

Something has been wrong with all my images lately. The entire left side will look awful. That was the bottom of this image and I cropped it out. I just took 85 300sec subs of the Bubble last night (stacked 78 of them) and it looks really clean in areas and awful in other areas. I'm starting to suspect something in DSS. One thing I've been noticing thats kinda weird is I always take 30 flats and DSS always starts out with those and says "xxxx 1 of 21".

I'm extremely tired right now after the all-nighter and pretty put out with it all at the moment. After I get woke up and get something in my belly I will look into DSS a little more. I may need to go to another stacking program.

#6 Wouter D'hoye

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Posted 11 September 2013 - 12:36 AM

Hi,

I use DSS too with good results. Maybe you should take a look at just your darks or flats. Maybe something is wrong with those. Could you post te raw data for this image and the darks and flats in dropbox or something? Really curious what might be the problem.

Wouter.

#7 rflinn68

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Posted 11 September 2013 - 08:14 AM

What do you see wrong with it other than the massive halos? I just think 5 minutes was too long at f/4 on these bright stars. I was thinking with some shorter subs and a layer mask I might be able to fix it.

I ran my Bubble nebula data last night in DSS and it seemed to be fine. I took a lot more subs and it seemed to be much better. The heat we've been having lately is the root of my problem I believe. I need a lot more subs when the sensor temps are 30*+ C.

Cooler weather is on the way though so I'll try to get by a little longer with my DSLR. Maybe by next summer I can get a cooled mono CCD.

#8 rflinn68

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Posted 11 September 2013 - 10:52 AM

Is this any better? I was a little less aggressive with the stretching. The halos are there right out of DSS. I think its just that 5 minutes at f/4 is too much.

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#9 rflinn68

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Posted 11 September 2013 - 11:02 AM

I'll work with a mask later and see if I can reduce the halos and still bring out the nebulosity.

#10 Jeff2011

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Posted 11 September 2013 - 11:21 AM

I wonder if this target would benefit if shorter exposure frames were combined with the 5 minute frames using the Entropy Weighted Average stacking method. I had seen an example of this on the DSLR forum on a glob with great results. The core was not blown out and showed incredible detail, without obscuring the outer stars of the cluster.

#11 Madratter

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Posted 11 September 2013 - 11:25 AM

I like this result much better. Personally, and this is a matter of taste, I would not bother with the halos any more than I would bother trying to get rid of the diffraction spikes. They are an aspect of the equipment used. But that is me.

#12 rflinn68

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Posted 11 September 2013 - 11:55 AM

Jeff, Thats what I plan to do next time I have that scope out. I'll look into that Entropy Weighted Average stacking method. Thanks!

Madratter, I personally like the diffraction spikes in my images but these are over the top. I replaced the spider in my dob with a 3 vane curved spider for observing but I think the spikes look good in pictures. I can do completely without those halos though.

#13 SergeC

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Posted 11 September 2013 - 04:02 PM

That second one is really good. I'd be happy to call it done if it was mine.

#14 CounterWeight

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Posted 11 September 2013 - 04:50 PM

Agree with Madratter on the imaging artifacts - just part of doing business. Like this second version much more. :)

#15 Wouter D'hoye

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Posted 12 September 2013 - 12:35 AM

Hi,

Agree to what's said above. New version looks much better. Though I'd like to see a full sieze version too. Image artifacts can never be entirely removed. Unlesss you want to give up large part of the actual image or spend countless hours in processing. My opinion is that you sould do as little as possible to your image. Often I like a noisy image with many details much better than an overcooked image as smooth a s a babyskin but lacking all detail. The trick is to find the perfect balance in this. It looks like you found that balance in your second image.

Wouter.

#16 rflinn68

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Posted 12 September 2013 - 10:00 AM

Thanks Wouter, You can see a full sized version by clicking on the original thumbnail in my first post in this thread. I uploaded the new one. One or two on Astrobin have said they like the first version better so I cant please everyone. The halos are still there in the 2nd version but with less nebulosity. I will have to take shorter subs and mask it to fix it. I tried playing around with mask as it is last night but was not able to do anything with it. Oh well, lesson learned here. Same thing with that scope on the core of M81, blew out the core, needed shorter subs.

#17 Wouter D'hoye

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Posted 12 September 2013 - 11:03 AM

Thanks,

Second version is a big iprovement. The nebulae look really natural in this version. Great job!

Wouter.

#18 hytham

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Posted 12 September 2013 - 11:18 AM

Your 2nd iteration is far better. Great work, Richard.






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