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M101, Half-way there

perfrej

By perfrej
in Imaging - Deep Sky

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perfrej

perfrej

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The weather has been exceptionally good the past two or three weeks up here and I have had some time to test my stuff. Since I am 14km from Stockholm city centre I opt to image stuff that is high in the sky. M101 and most of the stuff in Ursa Major satisfies that criteria. I am about half-way in collecting this data and testing the scope - in need of some more adjustments to get a straight focal plane and thus round stars all over.

Skywatcher 190MN (chipped primary edition :()

QSI 683wsg8 with Astrodon filters

10Micron GM1000HPS (unguided)

All subs 5 minutes in length, 28xL, 11xR, 11xG,16xB

Capture with CCDAutopilot, MaximDL, FocusMax

Pre-processing (sky flats and BIAS) in Nebulosity

Processing in PI (15 minute job - will do more with more data)

Full size here: http://filer.frejvall.se/M101_v1.jpg

/per

M101_v1_1024.jpg

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perfrej

perfrej

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Updated version with some more data. The total is now 44xL, 13xR, 15xG and 20xB. I lost a bunch of reds due to passing thin clouds last night. Sunday will be clear again and I will try to get the final bunch then. There is a subtle difference made by the new data. The stars are slightly rounder as I fixed the tilt of the camera yesterday and the resolution in the central core, especially in red, is slightly improved.

An interesting thing to note is that PI weighs each sub on noise and background level when stacking. As it took the previous bunch from cache, all having weights around 1.0, I noticed that the new subs were entered up to 1.2 in weight. Therefore, the star shapes are even more improved when the new subs with better stars get more "say" in the stack. I like that!

Anyway, we'll see what comes out of this. Perhaps I even get time to collimate the scope properly and fix the mirror offset. Who knows?

Big version at http://filer.frejvall.se/M101_v3.jpg

From the land of dimishing returns, all the very best,

Per

M101_v3_1024.jpg

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Yoddha

Yoddha

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Stunning image Per!

I hope that you don't mind that I played a bit with your image. Just gave it a fast try in PS with Smart Sharpening over the whole image. The left is the original, the right is reasult...

post-3188-0-04319100-1365763347_thumb.jp

If you backup the stars before applying this filter, you can save the good color there :)

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perfrej

perfrej

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Yoddha,

I definitely do not mind, but I do find the sharpening arteacts too much for my taste. When I get some more colour data I will sharpen it with a mask and rescue the stars from the horrible black circles they get from sharpening.

Coco, thanks!

/per

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Yoddha

Yoddha

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Per,

It was a fast and dirty applying of the parameters that I used the last time - just to illustrate what I mean :) In my images I alway make a layer with all stars before applying the deconvolution...

Definitely your image is great and I'm looking forward to see the next version :)

Ivo

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ollypenrice

ollypenrice

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Very good image. I think the sharpening, maybe a bit less aggressive, would be a good idea for small parts of the image but you can't just apply it globally. I would always sharpen a layer underneath and then erase the bits I wanted to see sharper from the top layer. I hardly ever sharpen stars. I won't say 'never' but it is close to never.

Not much sign of Stockholm in this one! Very impressive.

Olly

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Yoddha

Yoddha

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Per,

No bad feelings at all :)

The office monitor is with big resolution and there the Smart Sharpening looked better, but on the laptop monitor it is not so good... Definitely it is powerful tool but has to be used with care :)

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