Monday, April 11, 2011

Nikon Interval Timer

I find Nikon's intervalometer in their D3 and D7000 cameras to be a bit peculiar. It's pretty obvious that if you set an interval shorter than your intended shutter speed, the intervalometer will fail at the second exposure, since the shutter will still be open when the second frame should be fired. So, you can't for example, set a 1s interval and a 2s exposure. Nothing wrong with that.

But if you wanted to take a 30s exposure, you would think that setting a 31s interval would be fine, yes? No! In fact, even 32s doesn't work. For some bizarre reason, you have to set the interval at 33s, and then it will happily click away. I can't see the reason for this: I don't imagine that the shutter speed is inaccurate (although I haven't timed it), and I can't seeing if being a buffer/card writing issue on a camera like the D3 that shoots 9 frames per second (besides, there isn't a 3s delay between exposures anyway, more like less than 1s), but it works and does the job.

As I see exactly the same behaviour with the D7000 and D3, my assumption is that this is how it was designed to work.

Having finally figured this out, I now know that a D3 used like this with a fully charged EN-EL4a battery will take around 370 30 second exposures before the battery dies completely. Obviously this will vary a bit with temperature, but I guess you are looking at 2 to 3 hours of star trails under most UK conditions, which equates to around 30 to 45 degrees of rotation. It will be interesting to see what the D7000 can do, as I have an idea for a project that using this technique that the lighter D7000 will be better suited to and where external power won't be an option.

For now though I am going to concentrate on the D3, as I have an EH-6 mains power supply (a legacy from D2x days when you had to power that camera from the mains in order to clean the sensor), so there's the prospect of capturing some pretty spectacular star rotation.


Don Dennis said...

I just wish they would allow 9,999 photos to be taken, rather than only 999. I'm making time-lapse videos of orchids growing, and am using the mains power of course, and have some sequences of shots taking place for 2 to 4 weeks, with photos at 5 minute intervals.

Anonymous said...

I think the a 30 second exposure is actually 32 seconds because the doubling of EVs is rounded in certain instances for convenience (1/8, 1/4, 1/2, 1, 2, 4, 8, 16, 32). Hence needing 33 seconds for a 30 (=32) second exposure.