It's clear from the responses to my write up on 'How I shoot star trail photography' that many Nikon D800 users have experienced the same bewilderment with the built-in Intervalometer that I initially did when out in the field with my camera. The D800 user manual isn't constructive in explaining how to use the function effectively.
The critical factor to getting this right is to understand what the 'Interval' is. In plain English, it means the time between two events, and in our case, you'd expect it to mean the interval between the shutter closing on one frame to the shutter opening for the next frame. Unfortunately, Nikon's understanding differs confusingly.
In Nikon English, the interval is the time starting with the opening of the shutter to the closing of the shutter plus the time it takes to reset the shutter for the next frame. Whatever time you set the interval to be, you have to set the shutter speed plus a little extra time for the shutter to reset to fit within the interval.
For example, if we manually set our shutter speed to be 30 seconds, our interval has to be longer, say 32 seconds. If you set the interval shorter than the exposure time, it merely skips a large proportion of the chosen number of frames.
Camera settings for star trail photography.
To start with you'll need to set your camera on the tripod, compose and focus your shot-making sure you put your focus to manual. You don't want the camera to try to autofocus before each shot.
Let's say we have decided to take a series of 250 thirty-second exposures for our star trail photo.
Set the camera in manual and set the shutter speed to 30 seconds.
Then go into your camera settings and find the Interval Timer Shooting section.
You can pre-define a time to start the shooting, but you'll want the photos straight away so select 'Now' and press right on your D800 selector dial.
On the Interval display, you set the length of the 'overall' interval our 30-second shutter speed plus a short time for the shutter to reset. Two seconds will be sufficient, anything over ten seconds for the shutter to reset will give you dotted star trails. Lets set our interval to 32 seconds and press right on the D800 dial.
Next, we set how many exposures (times) we want to shoot. We want 250 exposures, so we set 250 in the three boxes X 1, which equals 250 exposures. Don't think that 250 X 2 = 500 exposures..it doesn't. That single value denotes how many frames will be taken in the ONE INTERVAL. We could, for example, want the camera to take five quick frames in one interval every 5 hours, but we only want one because we can only fit one 30 second exposure in our 32-second interval - get it? So we'll leave that on 1.
Press right again on the selector dial, and you'll return to the Start screen where you can now see your added values at the bottom—32-second Interval with 250 single frames.
Now press OK, and your camera will begin to take the 250 frames...so sit back, put your feet up and watch the stars go by.
About Robert Rhead
Robert Rhead is a English landscape photographer, UX/UI designer, web developer and graphic designer. He currently holds the LRPS certificate from the Royal Photographic Society, has won English and international photography awards and has featured in various high-profile photography and lifestyle magazines.