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Newbie Question - Orion
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Actually, this one I tried. I sync'd the entire image set and ran it through Sequator. I think Sequator did an okay job but when I took it into PS, I really didn't see even a hint of nebulosity. So I'll better til I can get more data.

The next opportunity to shoot I think I will:

1) Wait for my subject to be higher in the sky

2) Use my 24-105/f4 lens. I can shoot this lens wide open with good results.

3) Use my high end pollution filter on that lens to see if it helps.

4) Use Backyard EOS to better manage the session. From indoors.

5) Get a good set of calibration frames.

6) Use Siril rather than sequator to register and merge the frames.


Now - All we need are some clear skies.

Thanks! Jeff


You can also try using a gradient filter in Lightroom during post processing. Just have it start from the side with light pollution and drag it across. You can mess with the strength and length of the gradient to get a more natural look. 



I had a Canon Rebel T6i when i started and the clip in filter that Lou mentions will help a lot. Additionally, depending on your target, you may want to us a longer focal length lens to capture a smaller area. 

Scott Vanaman


Without knowing more information If you're having a problem with DSS finishing it's probably because the swap directory isn't large enough. Try increasing the size and see what happens.

Also, that close to the horizon your going to be hard pressed to avoid light pollution in these parts. A light pollution filter will help for sure but you will still need to fine tune the gradient with software. Keep up the good work.



The camera time was 21:20 and it looks like that is about 1 hr 15 mins fast so I'd say right around 20:00. PlanIt says Dark Night started at 18:15 so it appears we were into dark night.

Currently, I use Lightroom, Photshop, and Sequator. DSS never finishes on my computer. I plan to try out Siril, that seems to have some promise. Also, I'm looking at BakyardEOS and definitely see the value in that package.

I did use a linear gradient in LR and it did a pretty good job of evening things out after I cropped out the trees. I might be able to do something with a luminosity mask in PS.

Thanks! Jeff


Yes, there are a couple of things you can do to deal with the gradient. You can expect good results with time and practice. First off, nice job collecting pinpoint data. looks like you even caught a satellite zipping through Orion.

The easiest way to deal with light pollution is to deal with it before it reaches your sensor. Astronomik makes clip-in light pollution filters designed to use with your mirror-less camera. They make a a variety of filters but you need to be sure that the one you select will work with your modified camera. I think you had mentioned that your camera was modified to full spectrum in which case you will need to buy the CLS CCD clip on filter. They are usually a little more expensive than the the other light pollution filters designed for unmodified cameras but you will need that specific one because it will also block the the longer wavelengths of IR light that need to be dealt with. See attached for the range of wavelengths it lets through vs the wavelengths both types of filters block.

Another method you could use is to try and deal with it in post using the various tools available. Some work better than others and at the very least require some familiarity with the software. This specific image might be a bit tricky because the trees may confuse the software, unless up want to take to time to remove them.

What time was it when you took this image? was it completely dark out yet?

You may also benefit from taking exposures when dealing with a target bathed in light pollution. Another way to help limit the light pollution is to wait until the target is highest in the sky. Since we are so far North, you don't have too many options with this guy. This is such a large target, it's not going to be easy to remove the gradient but I definitely think the image can be improved.

This a good opportunity to practice using the various tools available out there and see try improve. I don't know what software you prefer -- there are a multitude of instructional videos on you YouTube. That might be a good place to start. If you have any more questions, feel free to post your results here perhaps we can dedicate a future workshop on how to deal with this problem.

Clear skies,


This image was taken from Green Lane. I have about thirty images of Orion and 150 Bias frames. It was taken with a Canon EOSR modified, a 40mm (photography) lens, 60 second tracked exposure, ISO 1600.

My question: Is there anything I can do about the light pollution causing the uneven exposure across the frame? Either with post processing of what I already have or wait until I get under the sky next time?

Jeff, wa3riz

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