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05-26-2014, 04:38 PM - 4 Likes   #1
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AstroTracking - first attempt out in the field

I have been following the Astrophotography threads here on the forum since they started, especially with the GPS unit. About a month ago, I actually ordered it, and the Pony Express guy dropped it off as he rode by about a week or so later. I experimented with it a bit in the back yard, made some foolish errors, but it worked right out of the box - calibrated up, and tracked. So, now I need to go take some neat sky images with it.

Yesterday, all was quite in the house - so I had a decision. Go East or West? West would be darker, east would have some interesting scenery to include. Coin toss - heads, so go east old geezer. About a month ago I was out to the Lost Dutchman State Park and shot the Superstition Mountain. That seemed to be a good destination. Here is a post from that trip (and some comparison images) - just for reference.I leave the house at 8pm its dark and get there at 9pm. I thought that I would try a slightly closer location, but all the trailer campers with their 52" TV screens watching Satellite TV, did that idea in. So, I went back to were I was last month - all by my lonesome, and its dark. So far, so good.

I setup, turn on the GPS and camera, lock on the birds, calibrate the unit - it locks and cals just fine. I setup the shot with my 8-16 @ 8mm wide open with f4.5, ISO 1600 and I capture the [first image] down below with an exposure of 60 seconds. Take a look at it and see that I am sort of rolling down hill. What I found out is, that with the GPS unit engaged, its impossible to use the viewfinder (between the GPS unit on top and the rear monitor screen lite up) - as if its going to help, its so dark out. Liveview is useless too. as its too dark. So, I decide to frame and adjust by taking images - and this approach worked out surprisingly well (It also helps in live view with the level on the screen in order to try to maintain some control in movement). Also, a ballhead is wonderful for most things, but for small corrective adjustments - it does leave a lot to be desired. I have been thinking of a geared 3 axis head like the Manfrotto 410.

Through an iterative process of of shooting and chimping - adjusting the position in the blind (dark) and then taking another round, I get things framed. I also go to the long end of the lens - 16mm. This works out pretty well. I also go to some longer exposures 120 seconds. Another thing I wanted to try was to find out with the tracking of the sensor, just how "muddled" the landscape would get. What I found was that 40 seconds is about the upper limit to having some good definition in the static landscape while tracking the stars. That needs to be qualified a bit. The farther away, or the wider the lens you use, the smaller the landscape features and thus sharpness can be further degraded. Here is the final image that I shot - which is the [second image] down below. This was done using a Voightlander 20mm at f3.5, ISO 1600 at 40 seconds. I went to the 20mm in order to be able to stop down the aperture from f4.5 to f3.5. Depending on how sharp you want the landscape features, it looks like right now you can shoot between 40 to 60 seconds in duration. Also, the landscape features provide somewhat of a painted look. So that was one question that I had - that is now answered.

I was really after the Milky Way, but the landscape that had the presence was to the ESE - pointing about 125 degrees. So, you take what you have, because the mountain isn't moving - any time soon.

I actually was thinking that I would be able to get better definition of stars that what I actually captured. Also, off to the the right of the image, is the greater metro Phoenix (an hour away) and almost at the foot of the mountain the downtown Apache Junction. I was somewhat debating on what to do, how much light pollution I was going to get. I actually thought that 1600 would be plenty. Why, I didn't go to ISO 3200 in order to get some additional light, and try either or both the Contax 28/f2.8 or the 31/f1.8 I can't tell you. I brought the lenses, I just forgot. It looks like that there is additional detail there in the sky that can be captured. So the moral of the story is dial up the ISO and pop on other faster glass and experiment more.

I packed up and then took the truck farther up the Apache Trail to a vista area, that was more protected from the light pollution. I wanted to shoot to the north where the Milky Way is. The last image [third image] is with the 10-17 fisheye at 17mm, 120 seconds at ISO 1600. I tried 10mm, but as various traffic was driving by, I was getting headlights, so I moved from 10 to 17 to try to fix that. Should have gone longer - using the full 5 minutes and bumped up to ISO 3200. Live and learn. The Milky Way should have been at around 45 degrees. This was shot pointing at 54 degrees. It looks like that there was additional light material there in the frame - I just did not capture it.

The last image [fourth image] was again with the fisheye at 10mm, wide open at f3.5 for 300 seconds, ISO 1600. I looks like the entire Milky Way was captured to some extent, but again light pollution from Phoenix was there. I am thinking that perhaps ISO 3200 would have been better, but the glow from Phoenix might have just washed it out. Also at 300 seconds the stars around the edges - in particular the corners are starting to trail.

With the camera angled up for some elevation, it is difficult to have access to the rear screen for the setup. A tethered ability would really be nice.

One thing I need to do is to learn how to post process the sky images better with Lightroom.



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05-26-2014, 04:44 PM - 1 Like   #2
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Whoa.... are you getting nebulae in that second image above the butte?!

Thanks for sharing your experience, as this just tells me I need to move to the desert before I stay up all night trying this stuff!
05-26-2014, 05:19 PM   #3
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Very good photos. What a fabulous sky. If I go outside my home, and try a 10 seconds shot, the sky is orange. I envy you.

Thanks for sharing your experience.
05-26-2014, 05:28 PM   #4
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Much better results than my attempts with the tracer so far. Impressive!

05-26-2014, 07:02 PM   #5
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Wow, very nice. I scouted out an area to try the meteor shower the other night, but ran into cloud. This gives me an impetus to try again.
05-26-2014, 10:35 PM   #6
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Very nice!
05-27-2014, 04:00 AM - 1 Like   #7
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QuoteOriginally posted by interested_observer Quote
It looks like that there is additional detail there in the sky that can be captured. So the moral of the story is dial up the ISO and pop on other faster glass and experiment more.
QuoteOriginally posted by interested_observer Quote
One thing I need to do is to learn how to post process the sky images better with Lightroom.
Congratulations. What a start with your O-GPS1!

I just wonder, if Lightroom alone will do full justice to your fine captures? I believe (from my own experiences) that a "real" digital image editing software would be a benifit once you have developed your raw files in Lightroom.

Hopefully with your permission, I have allowed myself to play just a bit with curves and levels on your second image:

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05-27-2014, 07:38 AM   #8
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QuoteOriginally posted by Stone G. Quote
Congratulations. What a start with your O-GPS1!

I just wonder, if Lightroom alone will do full justice to your fine captures? I believe (from my own experiences) that a "real" digital image editing software would be a benifit once you have developed your raw files in Lightroom.

Hopefully with your permission, I have allowed myself to play just a bit with curves and levels on your second image:
Good Morning Stone,

What a difference!!! I knew that there was additional detail and color there, but I just did not have the skill and talent to draw it out. You most certainly have my permission. My question is what did you use? ... and how did you apply it (general approach, work flow, etc.)? - beyond skill, talent and an artistic eye! Looking at it some more, the additional detail, and even the "feeling" of clarity has been enhanced.

In reading the past threads on astro, I have been following and noting the problems folks have been having with calibrating the unit - to the extent of parking the truck and walking across the empty parking lot to calibrate it (away from large hunks of metal). Over the years, as I have acquired items, I have tried to acquire with an eye towards this - another form of evening/night landscape/cityscape ambient low light photography.

I have been teaching myself Lightroom - so for this, I just googled "astrophotography post processing lightroom", found a couple of youtube "tutorials", and followed along. I figured that if I was able to bring out between 1/3 and 1/2 of what was there, that was a good start.

I am just starting to get the feel of the combination of higher ISO levels along with aperture. 98% of my stuff has been down at ISO 80 in order to capture the greatest amount of dynamic range with the lowest noise. Even with some f2.8 lenses, I have been shooting at f5.6 to f8 depending on the lens to capture the greatest resolution coupled with large depth of field. So, using really high ISO with the lens wide open is out on the edge of the diving board. Also, I have been letting shutter speed go to where ever it needs to. With this approach (using the o-gps) clamping down on the length of exposure so as to limit the muking up of the landscape detail is also a different approach.

Actually, if folks want, I can post the RAW file making it available for downloading. Let me find a large file transfer service and I'll post it.

05-27-2014, 09:00 AM   #9
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For folks that would like to play with the file (the second one), I have it up (full resolution raw .pef - right out of the camera) on a file transport service.As Stone has so eloquently shown, there is a lot more information there in the file, just waiting to be unmasked. Just post the results here - as I would like to see what is possible with this - and learn.


Last edited by interested_observer; 05-27-2014 at 09:06 AM.
05-27-2014, 02:00 PM - 3 Likes   #10
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@interested_observer: There are people here at PF that are infinitely better than I am at post-processing of astro images so I am as keen as you are to see and learn what can be done with your raw file. Still, you asked:

QuoteOriginally posted by interested_observer Quote
My question is what did you use? ... and how did you apply it (general approach, work flow, etc.)?
So, for what it is worth, here's my humble workflow. Due to my light-polluted skies, I am mostly into deep-sky photography and use my raw files undeveloped in a software like Deep Sky Stacker, so I have nothing to contribute with in terms of raw developemnt, But it seems to me that you have done just right and not over-developed your raw files. And thereby to the post-processing as I apply it in a decent little raster program, PhotoImpact X3 (that was unfortunately bought by Corel jut to be butchered):

0. Stretch your levels
Stretching levels is a procedure in which levels are distributed more evenly over the entire range from 0-255. This isn't really part of the processing, as it will usually lead to gross enhancement of the noise also, but it is amazing how this simple (in most software automated) algorithm may reveal faint levels of light otherwise hidden to the normal eye:



This helps me ascertain whether I have captured enough photons to work with or not.

1. Enhancement with curves and levels.
With curves and levels, one can selectively enhance certain levels of light, contrast and colours colours. It goes something like this:



However, it can be quite laborius to get it "right" by dragging sliders and curves more or less by trial and error - and I am a lazy man! Thus, I have applied a technique borrowed from High Dynamic Photography in which one automatically manipulates levels in a single image to mimic the outcome of a real HDR image. It would be quite lenghty to explain, but many moons ago, I actually did a small presentation of my technique here:

HDR = Poor Man's Raw

2. Try pseudo-LRGB techniques
Astro-images produced using pseudo-HDR techniques as desribed will often turn out a bit harsh-looking and thefore, I have borrowed a procedure used by some in CCD monochrome astrophotography with coloured filters - the so-called LRGB technique, where high-resolution greyscale images are blended with a low-resolution RGB colour image.

Thus, a final step for me may be as follows:

2.a Produce a grey-level image from your enhanced photo:



2.b Now place that grey-scale image on top of your original image and blend the two images using "luminosity only". Now you can set the transparency of your greyscale image to reach (hopefully) the result that you desire:



EDIT @ 11:21 p.m.:
3. White Balance

Ah yes, I almost forgot: After you have done all your manipulations, you might want to apply a finishing touch in WB, (I have to be careful here, though, as I am red-green colour blind):




This is of course a rather crude overview only; there are endless variations, but the basic tools - curves, levels, layers - remain the same.

Have fun!

Last edited by Stone G.; 05-27-2014 at 02:24 PM. Reason: addendum
05-28-2014, 04:05 AM   #11
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Good Morning Stone,

Thanks ever so much for the general approach and workflow. What was very helpful, actually very valuable was the thinking behind the approach and why you were including in within the workflow.

Also, I have been going through your website. There is a lot of very good and valuable information there that can be applied.

05-28-2014, 01:02 PM   #12
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Just chiming in to say I'm subscribing to this thread, there's a lot of good info here on post-processing for a noobish individual like me.
This is quite impressive and eventually I hope to go somewhere dark enough to do this myself.
05-28-2014, 06:49 PM   #13
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Wow! Looks like you got the hang of the o-gps1 pretty quickly! Well done!

I took the liberty to follow your suggestion of doing pp on your picture. I downloaded the resized version from this post as the link seems to work only with members. I have Pse11 on my computer with newly added some of the topaz suite: DeNoise, Adjust, Clarity and Detail. I ran the picture through all of them. I'm still just learning myself. I find the adaptative exposure tool in adjust really helpful in bringing out the details in the milky way and the nebulae. So does the micro contrast tool of clarity. I may have pushed a bit hard on some buttons, as I say I'm still learning. It is kind of a "poor man's" solution (less than 200$ for pse and the topaz tools). The real way would be to get PS and software like pixelInsight and do the techniques Stone G. showed us.

05-28-2014, 08:28 PM   #14
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QuoteOriginally posted by TER-OR Quote
Just chiming in to say I'm subscribing to this thread, there's a lot of good info here on post-processing for a noobish individual like me.
This is quite impressive and eventually I hope to go somewhere dark enough to do this myself.
Evening Terry,

I am delighted that folks are finding this both interesting and valuable. There is no way that I could - all by my lonesome, be able to apply the various types of processing with the tools that have been applied so far.

QuoteOriginally posted by SunValley Quote
Wow! Looks like you got the hang of the o-gps1 pretty quickly! Well done!

I took the liberty to follow your suggestion of doing pp on your picture. I downloaded the resized version from this post as the link seems to work only with members. I have Pse11 on my computer with newly added some of the topaz suite: DeNoise, Adjust, Clarity and Detail. I ran the picture through all of them. I'm still just learning myself. I find the adaptative exposure tool in adjust really helpful in bringing out the details in the milky way and the nebulae. So does the micro contrast tool of clarity. I may have pushed a bit hard on some buttons, as I say I'm still learning. It is kind of a "poor man's" solution (less than 200$ for pse and the topaz tools). The real way would be to get PS and software like pixelInsight and do the techniques Stone G. showed us.
Evening Sun,

That is one of the reasons why I posted the raw image file. I am both surprised and excited with the results so far. It would have taken me at least a few weeks of getting tools, experimenting - let alone coming up with various approaches that have been posted here so far in what - 2 days. I am learning so much. This is essentially crowd sourcing for astrophotography. I have gotten several ideas, along with thoughts of a couple of others.

One thing that I did, since I am sitting here at the kitchen table on a small netbook - too lazy to walk down to the office with the larger PC, is to use an image comparison tool to look at the latest results. The attached image is a screen capture of the compare too located at... between your result and stone's. Every successive set of processing, takes a different approach and reveals some additional details.I also came across an article by Topaz Labs on shooting stars that I posted in a thread of its own.This address the process more up front in terms of capturing the image. One technique that I did not remember - that I should have, was cranking the ISO all the way up, capturing a 15 second image, just for purpose of framing. That would have been a bit quicker. That and when I was satisfied with the composition, taking both a standard night landscape shot - with the landscape features sharp and with a large depth of field, then a series of astrotracking shots at progressive higher ISO levels against various exposure times. This way I would have had a wide assortment of image materials to select from. In this way, using Stone's level stretching capability if one combination did not work out, another combination would have. So, in this way - having a good understanding of the post processing techniques, can be wrapped back in to the capture process in order to improve the quality of the image take.

I just downloaded and watched the first video for pixelInsight processing. From that I have some additional ideas that I think can be applied.

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05-29-2014, 07:13 PM   #15
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QuoteOriginally posted by interested_observer Quote
So, in this way - having a good understanding of the post processing techniques, can be wrapped back in to the capture process in order to improve the quality of the image take.
Very true! 5 min more under the stars for 1 hr less at the computer! Keep us posted on your progress!
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