Since it is a fix overall angle, it may not be a problem. But there might be an issue at the border to the fix landscape, where the lightness may be reduced due to shorter trails.
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I am so intrigued by this idea. A friend has a Pentax where the sensor shifts to allow for a couple of minute exposure without a tracking mount. I think it has a builtin GPS to do the math part.
Like this shot so much and got inspired by harry’s and jonas’ takes, so here’s another one:
This time I also tried to make the mountians more visible. It is two RT processings, one for the sky with strong contrast by details and one for the mountains with strong denoising. Blended both in Gimp.
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How did you blend in the GIMP? Did you do it by hand? thx
I use luminosity masks as a starting point. Then I use curves on the mask to get the edge between sky and mountains. This time I also did some final brushing along the edge to smooth out the transition and get rid of small halos I still had.
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it turned out really natural looking
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Ooooo, what did you get Harry?
I’m not the most avid milky way/astro landscape photog, but I do like doing them when I finally get myself out there… One addition to the kit was a tracking mount… 
My sorry effort is below! (done in RT only). I was wondering what’s happening with the magenta stars in a number of the versions? I thought it might be a white point thing, so increased this is the raw tab, and it reduced the magenta, but not completely by the time I’d got to 3, which seemed to be getting quite extreme, so left it at 3.
Great picture Harry D.
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I got an iOptron 3302B. Seems like it’s strong enough for up to 100mm lens. I’m too lazy about using it. Got to get out there more 
Which one did you get?
I haven’t got one yet, it just remains on my wish list.
I was watching some youtube videos and as usual ended up Googling the equipment, I liked the looked of the Sky-Watcher Star Adventure: http://ca.skywatcher.com/_english/02_mounts/02_detail.php?sid=68, and then discovered the Vixen Polarie, http://www.myastroshop.com.au/guides/vixen-polarie.htm.
But before I jump in any further, I really need to prove to myself that I’d be disciplined enough to get out there regularly enough to justify the purchase.
So for now, I don’t have a tracker…
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It’s in essence solving a deconvolution problem. It’s somewhat doable for things like stars it’s a very fuzzy problem when talking about something like the milky way. In my opinion aligning a bunch of images and stacking them is a much easier and clearer Problem to solve than (blind) deconvolution. Why create the hard problem in the first case when you can solve an easier one?
[quote=“harry_durgin, post:13, topic:2972”]
My original plan was to stack a couple dozen shots, but it was windy most of the time up there and this was the only shot with a full 20 seconds of calm. (better tripod?)
[/quote]On some tripods there is a hook for attaching some weights. That should help.
[quote=“harry_durgin, post:13, topic:2972”]
I’ve now got a tracking mount, but I haven’t tried tracking the sky for a couple of minutes, then turning off the motor and shooting the landscape. I guess if I did that I could shoot at an even lower ISO and gain another stop of dynamic range… am I thinking that right?
[/quote]Essentially yes. I’d love to play with a tracking mount one of these days. A relatively simple tracker & dslr setup can take fairly impressive images.
For wide field photos I’m curious to see how well it performs compared to stacking. Stacking (with a stationary camera) does have some nice properties.
A fairly obvious one is that by rejection outliers when stacking you can get rid of distractions like airplanes automatically. At the same time if something interesting does happen in the sky you’ll get that too.
Another nice property is that because the image is ‘moving’ over the sensor you automatically get rid of hot pixels and some of the noise that’s dependent on the position on the sensor. In many cases I don’t even bother with darkframes anymore because of this.
The drawback is that creating a single photo results in some 20 GB of files. And the processing with the current tools we have is not very streamlined.
I’m curious about the pentax too. They seem to skip polar alignment and just use the gps + gyros which is really cool.
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Sorry for not citing correctly, I am writing from my phone. I guess you are correct about the convolution, but I think it is by no means blind, but maybe not so simple because of errors along the way. First, we have to get the coordinate system right. It is given by the star trajectories and may be described by conformal mapping. To get the parameters, hough transform or some flow analysis technique, maybe? In the transformed coordinate system, the deconvolution should be possible since the original kernel is known (a line of length of the star movement). What is missing is some options for the fix landscape. Of course, all of this is harder for the milky way than for regular star fields. Does this make sense? I am a noob at image processing but extremely fascinated …
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I hope you get somewhere with this Chris. Any software I seen that controls for star trails is Microsoft based. I would love to see convolution editing of night skies for the Linux community too.
I’m not an expert on image processing either.
What you say does make sense, and it has been tried:
I don’t know of any success story though. I guess in practice there are a lot of factors that play into this. Lenses are far for perfect. Cameras are far from perfect. The atmosphere is (at least at higher magnifications) far from perfect and so on.
What could also be interesting would be training a Deep Neural Network on the problem. After all that seems to be all the rage these days.
@harry_durgin do you have a link to something for windows that actually works well for correcting star trails?
hi @agriggio, did you do your version wholly in RT? I couldn’t work out how to get something out of the hills but keep the sky under control. How did you do it, please?! Maybe you could post up your .pp3?
I used two different Rawtherapee conversions as layers in McGIMP. Masked the hills using the scissors selector.
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Hi @RawConvert, yes, I did everything in RawTherapee. I kind of suck at GIMP, so I try to keep it simple and use only RT
Here’s the pp3. Basically, I used tone mapping, graduated filter and custom L* and CC curves to try to brighten the lower part as much as I could while keeping the sky reasonable. I also applied quite a bit of noise reduction, using Contrast by Detail Levels to keep the details. Finally, Defringe to fix the purple stars, and auto WB, increased contrast and vibrance, and a Fuji Velvia film simulation (from the HaldCLUT collection) for toning.
2016-07-26-23-40-37-0.ARW.pp3 (9.5 KB)
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I used darktable for editing, RawTherapee for noise removal and GIMP for scaling down and sharping the image.2016-07-26-23-40-37-0.ARW.xmp (8.2 KB)
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