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08-15-2018, 09:36 AM   #1
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Post & Discuss Your Astro Tracer Star Trails & Star Shots

I know there have been Astro Tracer and Star Trails images in the Night Time thread but with your permission I thought maybe a thread dedicated to star shots. I think discussing the images and techniques and offering suggestions would be helpful.

I'll start off with my first "successful" Astro Tracer shot. K-1, A 20 f/2.8, 2 min @ f/11, ISO 1600. I'm wondering if a longer exposure, wider aperture, or higher ISO would enhance this kind of shot. I'll try again tonight.


Also for those who have night tried it yet, the K-1 appears to go "dark" after the exposure begins and doesn't "light up" again until the exposure and processing are done which can be quite a long time.

08-15-2018, 09:43 AM - 2 Likes   #2
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I had my first outing with Astrotracer last weekend -- Its crazy how sharp it can keep the stars. I'm very impressed. I was shooting up to 1.5 minute exposures with very very little trails.
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08-15-2018, 09:57 AM   #3
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Wow, you've done better than me so far.
08-15-2018, 10:01 AM   #4
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QuoteOriginally posted by enoeske Quote
I had my first outing with Astrotracer last weekend
Those are very good first efforts!.
Mine have been a bit hit and miss. I need to read up on techniques before I go and then forget some stuff. I did use the OVF cover though.
I have found that I get trails at 180 and even 160 seconds with astrotracer on with a precision calibration. I did go to a dark sky location for my first efforts but I don't get the actual MW like that. I know PP is part of it and I have used Sequator so far.

For my next efforts I will do without I will probably try without tracer for a clean foreground. I do not have photoshop - so no masking is available to me just yet.

These shots are just a sea of stars to get the technique down.

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Last edited by Kevin B123; 08-15-2018 at 10:03 AM. Reason: Incomplete sentence
08-15-2018, 10:08 AM - 1 Like   #5
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Looking good Kevin.
08-15-2018, 11:17 AM - 2 Likes   #6
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Having played with astrotracer it can provide good results but it does require a good calibration, if not things go sideways fast. I haven't figured out a good way to test if it is correctly calibrated but the other day I read that you should bring a compass and check the compass in the camera against that to see if the calibration is good. I haven't had a reason to go out with the astrotracer recently so I haven't checked that this works.

My advice when using astrotracer is to do the following for best results:
1. Don't try for the 5 min max time you will be disappointed.
2. When calibrating it stay away from cars and other large steel objects, as well as away from power lines. These throw it off, same thing when using it.
3. For best results stick to 1/4 of the recommended maximum time it suggests
4. Shoot more straight up or more straight out, near 45 degrees it seems to get off quicker

I haven't had a chance to do much night shooting lately as life and the weather haven't been cooperative but I have some shots that I played around with from early spring that I took with astrotracer (I think I still have them).
08-15-2018, 04:29 PM - 3 Likes   #7
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QuoteOriginally posted by wtlwdwgn Quote
I know there have been Astro Tracer and Star Trails images in the Night Time thread but with your permission I thought maybe a thread dedicated to star shots. I think discussing the images and techniques and offering suggestions would be helpful.

I'll start off with my first "successful" Astro Tracer shot. K-1, A 20 f/2.8, 2 min @ f/11, ISO 1600. I'm wondering if a longer exposure, wider aperture, or higher ISO would enhance this kind of shot. I'll try again tonight.


Also for those who have night tried it yet, the K-1 appears to go "dark" after the exposure begins and doesn't "light up" again until the exposure and processing are done which can be quite a long time.
I think with the K-1 you could easily double the ISO and I'd definitely open the aperture. Just a stop or two down from wide open is all you need to sharpen the pinpoint stars. I don't think anything over f5.6 is going to sharpen significantly at night and will just rob the light. For the image you posted, you might try increasing the exposure and the contrast in post processing.

One of the major reasons I chose Pentax was because of the Astrotracer. I just use the recommended calibration and use no more than half of the time the screen says can be used (heck, sometimes I skip the regular calibrations and just jump straight to the precise calibration). My results:










This is a 15 second exposure of the Pleiades cluster taken with a 200mm lens.


This is a 6 second exposure of Jupiter, again with a 200mm lens.


The Astrotracer doesn't work well with the International space station. Without the Astrotracer, the ISS appears as a straight line.


but because the Astrotracer moves the sensor, the ISS appears as a squiggly line.


I haven't gotten to try the Astrotracer on Iridium flares or meteors yet.

Some people complain that their results sren't what they expected or desired but for the price and the ability to take long exposures without bulky or expensive mounts, I'm pleased with its performance.
08-15-2018, 06:54 PM - 1 Like   #8
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Here is the first photos I took once I got the O-GPS1 for my K-3. It had to be a work night so I couldn't stay all that long but went down to one of the county parks. This is a stack of six 60 second shots using my SMC Takumar 55 F/1.8 lens at ISO 100. I probably stopped it down to F/8 as I was just figuring things out then and didn't know what I was doing. I also don't think I got a great calibration, but not too bad. Most of the stars ended up being ovals about 50% longer in one direction. This was taken april 24th of this year which in MN means early spring with things likely still frozen.

I did just reprocess the image as I am getting better at it and was able to bring out the color more. Unfortunately there is always a lot of sky glow here and this was shot not long after sundown so it hadn't gotten really dark yet. The picture before this was the waning moments of sunset and was taken 15 minutes earlier. In the full size image M42 is visible and shows some finer details but not many.

Basically I have learned that you can get 10-15x the exposure time (3-4 stops) using astrotracer than you would without out and you can expect similar results as not using it. Assuming you have a good calibration.

08-15-2018, 11:15 PM   #9
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Thanks MossyRocks and gifthorse. I'm not getting the results like you especially the colors. So far I just get more pinpricks of light for longer exposures and the brighter stars become less distinct. The greater the exposure the grayer the sky becomes. I find that to make the brighter stars more distinct I have to back down the shadows, whites, and blacks to -100 in Lightroom.

Here are 3 unprocessed exposures.

120s @ f/8, ISO 1600.


120s @ f/5.6, ISO 1600.


150s @ f/5.6, ISO 1600.
08-15-2018, 11:20 PM   #10
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I processed this image to enhance the brighter stars.


Full image here.
08-16-2018, 07:06 AM - 1 Like   #11
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QuoteOriginally posted by wtlwdwgn Quote
I'm not getting the results like you especially the colors. So far I just get more pinpricks of light for longer exposures and the brighter stars become less distinct.
Likely a sign of light pollution and regular pollution interacting but even in great areas you will still get a brightening of the black sky from noise buildup and because the night sky isn't actually perfectly black. I get similar things when first stacked in DSS (Deep Sky Stacker) but then go and do more processing to get the blacker sky, better colors, and bring out the details in things. One of the regular posters in the astrophotography group had a post that contained a links to the tutorials he used to learn how to process astro pics. I can't ever seem to find that post from Pete_XL but I saved the links and included them below. Originally I found some tutorials from other people and the results were less than stellar but I thought I was doing well. I asked for feedback, got it, learned, and got pointed in the right direction.
A series on basic DSO processing
The full series on astro image processing

If you want to see an unprocessed but stacked image of what I am currently getting for the sky in my backyard here is one I took at about 2:00 AM on Sunday. It is a stack of 14 10 second (14x10s) exposures at ISO 800 using a 17mm SCM fisheye Takumar wide open. I stacked the image using DSS and did no additional processing. Granted the sky glow is exceptionally bad in this photo but my house is in a high Bortle 8 area and there was a lot of haze from the humidity plus the smoke from the Canadian wild fires. Vertically this covers an area from just above the tree line in the park behind my house to past the zenith (the tree at the top of the picture was actually behind me). The bright dot at the bottom in the middle is Mars.



Since your series of 3 images at 120s, 120s, and 150s haven't really been processed but are basically straight out of the camera I would say you are doing pretty damn good and have a nice dark area to work in with lower humidity and less pollution than I have. So much of getting good pictures from astrophotography is in the processing of them with learning and mastering that.

My suggestions for you on how to improve would be:
1. Start stacking (get DSS it is free and will work with the raw DNG files), it will help with noise and will also allow you the chance to bring out more detail
2. Learn how to process astro pictures. I'm still not great but getting better.
3. Decrease the individual exposure time to have less astrotracer error as well as digital noise but increase the number of stacked images.
4. Combine dark and bias frames in DSS.
5. If you don't have photoshop for astro processing, I would suggest using Gimp instead as it is free and the current version will actually allow you to work with the 32bpc tiff that DSS produces.
08-16-2018, 07:44 AM   #12
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Thanks for the feedback Moss!
08-16-2018, 08:06 AM - 1 Like   #13
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QuoteOriginally posted by wtlwdwgn Quote
Thanks for the feedback Moss!
Hopefully others can learn from my mistakes and not make them. I try to learn from others so I can not go down already tried and failed paths but instead I can fail in new and interesting ways that can add to the collective knowledge.
08-16-2018, 08:09 AM - 1 Like   #14
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Me too!
08-16-2018, 11:05 AM - 1 Like   #15
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QuoteOriginally posted by wtlwdwgn Quote
......I'll start off with my first "successful" Astro Tracer shot. K-1, A 20 f/2.8, 2 min @ f/11, ISO 1600. I'm wondering if a longer exposure, wider aperture, or higher ISO would enhance this kind of shot. I'll try again tonight.

Also for those who have night tried it yet, the K-1 appears to go "dark" after the exposure begins and doesn't "light up" again until the exposure and processing are done which can be quite a long time.
My largest suggestion is to change one item. Shoot wide open. There is so little starlight, you need as much aperture as you can get. Depth of field does not matter - with the distance we are talking about, it does not enter in to the discussion. Stopping down for sharpness - doesn't matter either. If you don't collect the starlight - sharpness is the least of the problems.

ISO 1600 is good, but personally - going with ISO 800 (with the K1) provides better dynamic range, and thus better overall color with the Milky Way.

QuoteOriginally posted by MossyRocks Quote
....My advice when using astrotracer is to do the following for best results:
1. Don't try for the 5 min max time you will be disappointed.
Exactly this! I've had my best luck with 50 to 60 seconds. I need to try 90 seconds - others have had good experiences with 90, but I just have not gotten there yet.
_______________________________

Last year about this time, I finally decided to upgrade from the K5 to the K1 in order to really get the Milky Way images that I wanted to capture. I needed to go to a full frame sensor. Here is one from a couple of months ago. K1 with the Pentax 15-30/f2.8 at 15mm f2.8, 50 seconds - 3 frames stitched (Microsoft ICE) with the GPS astrotracer enabled.


This last year has been really difficult for me just getting out. Everything has just gotten in the way of getting out and shooting, now that I have the equipment to capture what I really want to capture.

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