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01-30-2016, 05:36 PM   #1
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Interval shooting question

So I was playing around with the built-in interval shooting settings trying to get the hang of doing a star time lapse/composite type shot. I had a Rokinon 14 f2.8 on the K-30. The mode was Manual with an exposure of 30 seconds and ISO of 400 (I believe). Double checking today, both High ISO and Slow Shutter speed NR are off. Also, it was recording in RAW+.

Now, I've tried to do some reading and I'm seeing conflicting statements about how the interval timer works. I understand that there would be extra time needed with those NR settings turned on but I'm not sure I understand why some say the interval setting should include your exposure duration as well. Last night I originally had set it up following this line of thinking and I set the interval to 35 seconds with the 30 second exposure. However, this resulted in an actual 35 second pause between photo starts. I let it run for a bit but when I came back to check, it had stopped all together. So, I went back and changed the settings to a 5 second interval and started it up and it seemed to be going fine again but upon another return check, it had stopped once again. Both times it was set to take 100+ photos. The first round took 16 photos before stopping. The second took 43. There was still plenty of battery and room on the SD card.

So now I'm trying to figure out why it's stopping. In reading past threads, one possible cause was the buffer overloading because it couldn't write to the SD fast enough. Sounds logical but why was I able to get 43 photos the second time then? Is there anything else to check for that could be the cause of the problem?

I plan to do a more controlled test tonight or tomorrow if I get a chance.

01-30-2016, 06:44 PM   #2
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If you possibly gave the interval a littlle bit more time between shots during a test, that would tell you if it is able to process. Raw files are large, I have noticed. When you test, you might want to start with a low number of shots to see if the basic formula of what you are doing is successful (number, exposure length), then try more until you get to where you actually do exactly the amount of shots you need for a long period of interval shots.

You might want to check to see if your shutter release delay timer is set for any seconds also. I am not sure if that would have any effect between shots, but I wanted to mention it.

Last edited by C_Jones; 01-30-2016 at 08:54 PM.
01-30-2016, 06:56 PM   #3
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Good suggestion. I hear ya on the file size but looking at the file sizes, they are all a little over 13MB for both sessions. So it still seems strange that one only went 16 images while the other made it to 43.

I guess I also need to figure out exactly how much of an interval I can have while maintaining a solid star trail. I'm guessing someone has a formula or a rule of thumb somewhere out there.

I went ahead and stacked the images and this is what the result was. Nothing great and plenty of light pollution but you can see the short and long trails from the two sessions.

01-30-2016, 07:14 PM   #4
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In my K-5IIS manual it says "If the Auto Power off function turns the camera off during Interval shooting, the camera automatically turns on again when the shooting time approaches". It also says "If the subject is not in focus with the focus mode set to AF.S (Single mode) or if the [Interval] setting is too short and the previous image processing cannot be completed before taking the next picture, no picture may be taken"

I just wanted to point out those words. Maybe if you adjust your Auto Power off, that may give you better operating during your tests/shooting. If you are shooting in AF.S mode and the subject moves (such as stars) from your original focus, maybe the shooting could stop per one of the manual statements I mentioned.

That really is not a bad shot. I know the light around the buildings is showing, but it gives it the "real looking" effect and with the trails, which are not bad, it looks sort of like an interesting variety in one picture.


Last edited by C_Jones; 01-30-2016 at 08:57 PM.
01-30-2016, 07:40 PM   #5
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Yeah, there's some flare probably from when a car drove by and being in the landing pattern of our airport allowed me to capture the streaking "UFO".

I checked the K-30 manual and it basically says the same thing. My Auto Power Off is set at 1 minute so it was obviously working for a period of time after that auto off threshold. I could turn it off but I wouldn't want to do a long interval shoot with it off to save battery. Plus, being winter, I want to conserve battery to battle the cold as well.

Also, looking back at the file info, it appears I was incorrect about something. The first batch was 16 photos timestamped from 8:22 to 8:31 so it was taking one image every 30 seconds plus the slight interval. I know I had set the interval longer to begin with but that must be a very small batch of images I have on the card. The second main batch of 43 images was from 8:46 to 9:10 which also makes sense. So really, the settings were the same for both sessions.
01-30-2016, 08:06 PM   #6
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So you are alright with the auto power off setting. What you said about your first batch makes sense then. I had used some similar settings with the interval timing and number of exposures like that and it seemed to work. That seems like a method, and you can adjust using those settings as a basis.
01-31-2016, 07:14 PM   #7
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So it's kinda cloudy out tonight but I gave it another try to see what happens. This time I used a new Sandisk Extreme Pro card freshly formatted. This should have plenty of write speed and room. I also changed the interval to 10 seconds with 301 photos total to be taken. Unfortunately this time it only took 77. So, more than before but still not even close to what it should be. Battery is still full too. Just seems weird. I'll send it out one more time tonight to see what happens.
01-31-2016, 08:22 PM   #8
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Just to add to the confusion, I just set it up to take another session of photos. I changed the interval time to 20 seconds this time. However, as I started the photos I noticed that it was nowhere near 20 seconds between each photo. Using my watch to time each cycle, it gets even more odd. Though my exposure is set to 30 seconds I actually consistently timed it to 32 seconds from shutter to shutter sound. Then the interval was exactly 8 seconds each time with a total of 40 seconds for each photo. Can anyone help make sense of this?

01-31-2016, 10:07 PM   #9
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Went out and stopped, yes stopped, the shooting. After roughly an hour and a half it was still running and had 142 images. At 94 minutes with 142 images, that comes out to 40 seconds per image which is what I was timing on my watch. Checking the settings again, it still shows 30 second exposure and a 20 second interval. Doing a quick test just now, I set the interval to 40 seconds and still only get 8 seconds between images.

Pretty much completely cloudy now so I doubt there is anything to show for it. I just wish I could find a pattern here so I could know what to expect when I set this to run.

Hopefully someone else has dealt with the interval settings and can chime in. Perhaps I should post in the troubleshooting forum?


Ok, I'm getting it figured out and it's completely user error it appears. As people have mentioned numerous times, you have to include the exposure time in the interval time. What was throwing me off was an apparent minimum I guess for file writing that can cause issues. For instance, if I set the interval to 32 seconds with a 30 second exposure, it couldn't fire quick enough and would then cycle around another 30 seconds before firing.

In my previous attempts, I had the interval set too short and it was thus skipping an attempted photo and then going through the cycle once again. Man, what a pain. Talk about less than intuitive.

Last edited by colonel00; 01-31-2016 at 10:43 PM.
02-01-2016, 01:30 PM   #10
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QuoteOriginally posted by colonel00 Quote
Went out and stopped, yes stopped, the shooting. After roughly an hour and a half it was still running and had 142 images. At 94 minutes with 142 images, that comes out to 40 seconds per image which is what I was timing on my watch. Checking the settings again, it still shows 30 second exposure and a 20 second interval. Doing a quick test just now, I set the interval to 40 seconds and still only get 8 seconds between images.

Pretty much completely cloudy now so I doubt there is anything to show for it. I just wish I could find a pattern here so I could know what to expect when I set this to run.

Hopefully someone else has dealt with the interval settings and can chime in. Perhaps I should post in the troubleshooting forum?


Ok, I'm getting it figured out and it's completely user error it appears. As people have mentioned numerous times, you have to include the exposure time in the interval time. What was throwing me off was an apparent minimum I guess for file writing that can cause issues. For instance, if I set the interval to 32 seconds with a 30 second exposure, it couldn't fire quick enough and would then cycle around another 30 seconds before firing.

In my previous attempts, I had the interval set too short and it was thus skipping an attempted photo and then going through the cycle once again. Man, what a pain. Talk about less than intuitive.
Sounds like you are getting your timing about right then. Like you are doing, testing will tell. Even trying with 5 or ten shots should be informative.
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