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04-20-2018, 03:45 PM   #1
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Star Trail feedback need....

This past weekend I was in Big Bend National Park and had a blast. One of my todos was to take a star trail image. Well, I thought I understood the process, but clearly I need further understanding of how the Interval Composite feature works on my K1. How do I get the trails to be solid lines. Mine are dotted. The smallest Interval is 2 seconds. How do I get around this...

Let's see, settings were exposure time: 30 sec @ISO 400 at f/1.9.
Interval Composite started by remote.
I can't remember how many shots it was set at. A hundred maybe?

Composition stinks as I fumbled with this over several nights. This image was caught behind the hotel on my 4th day. No one of wanted to drive 45 minutes to my real site unless I guaranteed them a successful take. I was OK with that since I failed to produce the prior 3 nights!

So the question is, what did I do wrong or what setting am I missing. I did change the Custom settings that tells the camera to start the Interval when the shutter closed.

Regards,
Rodney

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Last edited by lazarustx; 04-20-2018 at 04:10 PM. Reason: Edited Images settings details
04-20-2018, 03:55 PM - 1 Like   #2
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I've never shot star trails, but it seems to me that you want an interval time that is going to be just ever-so-slightly longer than the shutter time... as close as possible, but not less than the shutter time.

I'll be interested to hear what our more-experienced members have to say.

EDIT: Even with the dotted trails, that's still a very cool shot
04-20-2018, 04:13 PM - 1 Like   #3
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BTW, the setting I changed was C13, set to 2 which states that Exposure begins after Standby interval passes after the completion of the previous post. I thought that I had a 2 second Interval, perhaps I had a larger interval which resulted in the large gaps in the trails....

Thanks @BigmackCam I fumbled for days trying to get this right..
04-20-2018, 05:35 PM - 2 Likes   #4
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It may not possibly be applicable to your situation, but the processing time of long exposures when the NR is on may cause a longer processing time than when there is no NR on, causing overlap timing when interval shooting if the processing time is not accounted for when setting the interval.

Shooting a single sample exposure using the length you plan on using, and seeing how long the processing takes also will tell you what the full process of each image is. Then you can adjust your interval timing to allow for it without overlap.

Like I said, this information may not be applicable. I just wanted to mention it just in case.

Good luck.


Last edited by C_Jones; 04-20-2018 at 05:44 PM.
04-20-2018, 05:47 PM - 1 Like   #5
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Long shutter time NR can create big gaps like these because the 30 seconds of exposure is doubled to collect 30 seconds of dark frame. But you may find that 30 second exposures with no NR have some noise (which can be corrected if you manually grab a few dark frames at the beginning and end of your shooting session)

Astro is always requires a bit of trial and error to find the best settings given the sky conditions (clarity, moon, light pollution, etc.). For that reason, I always take a few test shots (different ISOs and shutter times) in single shot mode just to gauge the light level in the sky. Then I take a 4-shot interval composite just to make sure all those setting seem right before I do a much longer interval composition.

You can also practice with different settings at home just to get used to setting up the camera. Even if your home skies are light polluted, you'll get used to the sequence of steps and settings needed to take these kinds of images.

Have fun!
04-20-2018, 06:38 PM - 1 Like   #6
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Here is mine from last night. Through the window cropped to get rid of the neighbors lights.

K-3II, Pentax-A 20mm f/2.8 @ f/2.8 ISO 400 30secs
180 x 30 sec exposures, layered and blended in Photoshop
Camera was set for a 33 second interval to allow for the 30 sec exposure plus time to save. All NR settings = OFF.

I am not sure you can entirely get rid of the gaps. Starstax has a blend mode that helps fill those in but I used Photoshop on this. Just testing at this point.
On the K-1 you can set C13 to "Standby Interval" and then interval setting to "minimum" so that it starts the next exposure as soon as possible. On the K-3II you have to adjust the interval for a little extra time, 3 seconds works with no issues, 2 seconds might work.
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04-21-2018, 09:45 AM   #7
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QuoteOriginally posted by C_Jones Quote
It may not possibly be applicable to your situation, but the processing time of long exposures when the NR is on may cause a longer processing time than when there is no NR on, causing overlap timing when interval shooting if the processing time is not accounted for when setting the interval.

Shooting a single sample exposure using the length you plan on using, and seeing how long the processing takes also will tell you what the full process of each image is. Then you can adjust your interval timing to allow for it without overlap.

Like I said, this information may not be applicable. I just wanted to mention it just in case.

Good luck.
OK. This leads me to a whole new set of questions. I'm shooting RAW. So is the camera still doing NR on the images? Maybe I need to check my manual again, as I was under the impression that NR only happened on JPGs....

Thanks for your feedback!

---------- Post added 04-21-2018 at 11:46 AM ----------

QuoteOriginally posted by jatrax Quote
Here is mine from last night. Through the window cropped to get rid of the neighbors lights.

K-3II, Pentax-A 20mm f/2.8 @ f/2.8 ISO 400 30secs
180 x 30 sec exposures, layered and blended in Photoshop
Camera was set for a 33 second interval to allow for the 30 sec exposure plus time to save. All NR settings = OFF.

I am not sure you can entirely get rid of the gaps. Starstax has a blend mode that helps fill those in but I used Photoshop on this. Just testing at this point.
On the K-1 you can set C13 to "Standby Interval" and then interval setting to "minimum" so that it starts the next exposure as soon as possible. On the K-3II you have to adjust the interval for a little extra time, 3 seconds works with no issues, 2 seconds might work.
Hmmm...I may have to give photo stacking a try on my next trial.

Nice shot btw!
Regards,
Rodney
04-21-2018, 03:09 PM - 1 Like   #8
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Turn NR off. If you need dark frames, you can do them at any time.

How to Create Dazzling Star Trail Photos, From Start to Finish

Startrails application

04-22-2018, 02:56 PM - 1 Like   #9
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QuoteOriginally posted by lazarustx Quote
OK. This leads me to a whole new set of questions. I'm shooting RAW. So is the camera still doing NR on the images? Maybe I need to check my manual again, as I was under the impression that NR only happened on JPGs....

Thanks for your feedback!
I am almost positive that the NR would cause for a lengthier processing time. If you are outputting RAW files only, NR settings most likely will not be affecting it. There is still a processing time for any RAW or JPEG file though. So, if you are shooting in RAW as you say, then you may want to do a set of sample individual shots and see what their processing times are. Then you can figure in that timing and any break you want when you set up your interval shooting.
04-22-2018, 05:12 PM - 1 Like   #10
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NR off, high speed continuous shooting with wired remote, manual exposure.
Try 20 second or so exposure time, adjust ISO and aperture for desired exposure level.
I would just shoot JPEG, that's just me.
Oh, and this nifty little program.

Software - StarStaX

Never mind, JATRAX already mentioned StarStax.

Last edited by Ex Finn.; 04-22-2018 at 05:18 PM.
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