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First galaxy (M81/82) - a couple of issues/questions


Paul-F
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I had a go at M81/82 last night, I collected 30 @ 3 mins iso 800 and 22 at 1 min iso1600 (lost about 15 overall to wind/trails). First proper go at anything so playing with the settings to see what effect they have. The moon was bright and washed out most of the sky visually, and a few clouds were whizzing by so wasn't sure what to expect tbh. Battery ran out after taking 5 darks and no flats so processed what I had.

Here's a single 3 minute unguided sub straight off the camera @ iso800. Given that I can easily get 3 minute subs unguided will a light pollution filter be of significant benefit (more exposure time but more contrast) ? Secondly, made evident in the second pic with some contrast adjustment, there's something up with the sensor I think (bottom edge on the left) and I have now seen this on daytime shots as well and when using different lenses .... on bright images I don't see it but can make it visible if I try. Any other comments welcome ....

Raw Image:

post-20262-0-93090500-1423324463_thumb.j

Contrast Adjusted:

post-20262-0-47214700-1423324970_thumb.j

Final stacked image with only 5 darks applied - still working on it as I seem to lose a lot of definition if I make the background consistently black.

post-20262-0-95877000-1423323719_thumb.j

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Hi Paul, nice shot! I went out to try these two last night, got the scope set up, looked up and the cloud had appeared out of nowhere!!!  :mad:

I think adding some flats would help with the final image, I can imagine the frustration when the battery ran out! Not sure what equipment you are using, but I "splashed out" on a £30 Skywatcher LPF and found it works pretty well in my basic set-up. I posted about it here:

http://stargazerslounge.com/topic/234757-skywatcher-light-pollution-filter-first-use/

If you can get longer exposures, you might also consider the Astronomik clip-in filters if you have a Canon. They are a lot more expensive, but probably more effective over longer exposures. 

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Hi Paul, 

Done a quick (2 minutes) background subtract for you, just to give you an idea of what software can do!

I am by no means an expert, only been doing this a few months myself, so Im sure others could do a lot more!

post-39747-0-39199400-1423336513.jpg

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Nice work! You could now use a plug-in like HLVG to remove the overall green tint and then something like gradient xterminator and it will look even better.

Looking into this, thanks! I have lightroom but not photoshop - is there a decent freebie out there that will get rid of the green stuff ?

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Hi Paul, nice shot! I went out to try these two last night, got the scope set up, looked up and the cloud had appeared out of nowhere!!!  :mad:

I think adding some flats would help with the final image, I can imagine the frustration when the battery ran out! Not sure what equipment you are using, but I "splashed out" on a £30 Skywatcher LPF and found it works pretty well in my basic set-up. I posted about it here:

http://stargazerslounge.com/topic/234757-skywatcher-light-pollution-filter-first-use/

If you can get longer exposures, you might also consider the Astronomik clip-in filters if you have a Canon. They are a lot more expensive, but probably more effective over longer exposures. 

My shot was 3 mins in moonlight so maybe not beneficial to the same degree but at that price it is worth a go I'd say ...

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Nope, program called Pixinsight, especially for AP.

Quick run through photoshop will get rid of the green as well:-

Ill stop messing around with your pics now! There are plenty of videos on youtube on how to get the best out of AP images. Tis a big learning curve!

post-39747-0-29152900-1423337043.jpg

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