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I have a Nikon D5300 and experimented shooting star trails but encountered a problem that I believe may be related to the Interval Timer setup. In order to take 99 30-second exposures I set the starting time to Now, the interval to 32 seconds, and the number of intervals to 99.

On my first attempt the camera stopped taking photographs after 41 exposures. I tried a second time and it stopped after only 20 photographs.

I found the passage below in the Reference Manual and was wondering if the problem might be that I did not set the interval long enough to allow the camera to record some images to the memory card:

“Because shutter speed and the time needed to record the image to the memory card may vary from shot to shot, intervals may be skipped if the camera is still in the process of recording the previous interval.”

Any help or suggestions will be welcomed.

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    \$\begingroup\$ What was the total elapsed time to take the 41 and 20 exposures? About 50 minutes for each run or a much shorter total time for each run? \$\endgroup\$
    – Michael C
    Commented Jun 26, 2015 at 22:40
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    \$\begingroup\$ Did you have long exposure noise reduction set? \$\endgroup\$
    – inkista
    Commented Jun 27, 2015 at 1:12
  • \$\begingroup\$ mattdm: Total elapsed time: 49 min./2 sec for 42 exposures; and 22 min./48 sec. for 21 exposures. Capture time between exposures was 1 min/4 sec. for almost all the exposures in both trials. \$\endgroup\$
    – R. Wiberg
    Commented Jun 27, 2015 at 20:49
  • \$\begingroup\$ Both Long Exposure Noise Reduction and High ISO NR were turned OFF. \$\endgroup\$
    – R. Wiberg
    Commented Jun 27, 2015 at 20:50
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    \$\begingroup\$ Sensors (and other camera electronics) can become too warm on long time exposures, especially a series of them, and the camera will shut down to protect itself. Though that is only a possibility, it seems likely that the second series was truncated more quickly because the camera was already warm. What was the weather like? You might try the same series in cold weather, after the camera has cooled. \$\endgroup\$
    – DrMoishe Pippik
    Commented Jun 28, 2015 at 3:35

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I found the passage below in the Reference Manual and was wondering if the problem might be that I did not set the interval long enough to allow the camera to record some images to the memory card: “Because shutter speed and the time needed to record the image to the memory card may vary from shot to shot, intervals may be skipped if the camera is still in the process of recording the previous interval.”

Yes, this surely is the case.

I discovered myself conspiracy about shutter speed recently. I needed to photograph long series and found out that camera takes photos gaplessly if I set interval to 32 seconds and exposure time to 30 seconds.

I was extremely disappointed that two cameras from different brands expose not for 30 seconds but for 32 seconds! It looks like cameras set the exposure using power of two divider or multiplicator to get exposure times other than 1" to get exposure times closest to traditional 1/125, 1/500, 13", 1/15, whatever, but I am not sure in that.

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  • \$\begingroup\$ I wouldn't think the actual exposure is 32 seconds. Most likely it's 30 seconds for the exposure plus some amount of time up to 2 seconds to write to the card? \$\endgroup\$
    – MikeW
    Commented Jul 11, 2016 at 23:02
  • \$\begingroup\$ @mikew: no, full 32 seconds between shutter clicks. Try it yourself using your camera: I can't bet on that it will behave in same way but I expect it to. \$\endgroup\$
    – Euri Pinhollow
    Commented Jul 15, 2016 at 19:33
  • \$\begingroup\$ @mikew 32 seconds is correct. Full stops are double the prior stop, and 1 second is the base, so it's 2/4/8/16/32 seconds. Similarly 1/30 is really 1/32, 1/250 is really 1/256, etc. \$\endgroup\$
    – Jim MacKenzie
    Commented Apr 19, 2018 at 22:55

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