Scratching your head and wondering what an Intervalometer is? We’ve covered that in this article, and talked about some super fancy Intervalometers in this article.
Before we launch into the tricks, let’s first get some terminology straight.
- Long Exposure – in my vernacular this is an exposure over 30 seconds – the limit of most DSLR cameras.
- TimeLapse – a series of photos taken over time that compresses (or expands) the actual time when made into a movie. Usually all the exposures use the same settings. An event that takes 3 hours can be distilled into a 30 second video. An event that takes fractional seconds – like a balloon popping – can be shot at high speed and expanded into a movie that lasts much longer. Usually expanding the time is called “Slow Motion”.
- StarTrail – like its timelapse brethren, implies a series of shots taken over time and combined into one exposure to show the star motion OR a StarTrail can be created from a SINGLE very Long Exposure.
- Bramping (aka Bulb Ramping) – a timelapse techinque in which the length of the exposure is changed over time to accommodate the setting sun, rising moon – anything that involves a gradual change in the ambient light.
How is a Timelapse different from a Star Trail?
The two are not different, except that by intention a Star Trail created from multiple exposures requires a minimal interval between one shot and the next or gaps result. For a timelapse – which can be taken at night or day – the key is having a regular interval between each shot. Changing the interval between shots has the effect of warping time.
Ok, Got it. Tell Us About the Tricks
Sub-Second Intervals
Why would you want sub-second intervals? For one, to catch as many meteors as possible. The second or so that the camera spends with it’s shutter closed is a second you might miss that brilliant fireball. Another reason to keep the interval REALLY short is to reduce or eliminate gaps in star trails. But sub second intervals are the hardest trick of all. There are almost no intervalometers that allow setting an interval shorter than one second, and even if it’s possible many cameras can not handle sub-second intervals. However, there are a few devices that can do sub-second intervals: Trigger Trap for one. The best way to find the shortest possible interval is to set up the camera and try! Set the interval to say 700 ms and see if your camera can run off a sequence of 15 to twenty 30-second shots without missing a beat. If that works, set the interval to say 500ms. Note that the minimum interval will depend on the camera, as well as the size of the image, and speed of the memory card. Once you find the minimum, leave a little extra time and use that. My Canon 5D Mk II was happy with 450 ms intervals between shots. That’s HALF of the waiting time of one-second intervals.
Shake Reduction – Mirror Lock Up
Many people worry about mirror slap. Mirror slap occurs when the little mass of the mirror “wiggles” the camera enough to blur long-ish exposure shots. Mirror slap is particularly pernicious in the 1/4 to 2 second exposure length. It may also be a problem if you have your camera attached to a delicately balanced telescope at high magnification. How do you solve the problem? It depends on your camera, but there are several approaches to try:
- Leave live-view on (which will eat batteries and may result in excessive warming of the sensor)
- Use the camera self-timer in mirror lock-up shooting mode. Most cameras will behave properly if your exposure length is not bulb. That is, they will move the shutter, wait for the delay to expire and then take the shot. Remember to allow a delay that is at least one second longer than the shot length plus the self timer delay. For example, let’s say you want to take as many 24 second exposures as possible but you need at least 8 seconds for mirror slap to stabilize. Set the camera to 24 second exposures with a 10 second self-timer. Then set the intervalometer to take a 1 second(!) exposure every 36 seconds. The reason for the 1 second exposure is to allow enough time for the shutter release to be recognized while the 36 second delay allows for 10 seconds of timer, 24 seconds of shot and a 2 second safety buffer.
- See the Maximum Shots, minimum interval trick. But instead of 1 second delays, change the length of the exposure to the amount of time you need for camera stability + 1 second.
- Want to do shake reduction in BULB mode and without a self-timer? Set the exposure length to the desired amount of time and use a short interval. With mirror lock-up on, you’ll get every-other exposure at the desired length. Note: this is the most “iffy”mode as it depends on your camera behavior.
- Finally for shake reduction in BULB mode WITH a selftimer, set the intervalometer as normal, but set the length of exposure longer and include the self-timer interval. For example to take 60 second exposures with a 10-second self timer, set the exposure length on the intervalometer to 70 seconds.
Variable Length Shots
While this technique seldom works well, you can allow the camera to determine the exposure length via metering. All you have to do to make this work is to have the camera take 1 second exposures (as before) no more frequently than the longest exposure you expect to take. Some fancier devices, like the Trigger Trap and the CamRanger can even be configured to change the exposure length over time. This feature is called “Bulb Ramping”.
Extended Self Timer
Got a big group shot and no wireless remote. Not a problem. Set the camera to a short (e.g. 2 second) self-timer delay, and set the shot delay to say 20 seconds – or as long as you need to safely climb on top of the human pyramid to get that perfect shot. Since you can allow multiple shots, you’ve all got plenty of time to change your poses, or re-architect your human pyramid. We use this trick all the time when we’re conducting workshops. It allows us to set up our camera and walk away while we instruct. We leave enough time to set up for the shot. Most cameras will blink or flash to let you know they are about to take a picture so everyone can time that cheesy fake smile. Note: If using a Flash, you can lengthen the interval between shots to give the flash extra time to recycle.
Maximum Shots, Minimum Interval
When not in Bulb mode, it can be maddening to not have the Intervalometer and the camera in sync. Set the camera to 20 seconds and the intervalometer to 19 and you’ll miss about every other shot. Bummer. Here is a trick to maximize the number of shots and not care much about the actual exposure time. Set the intervalometer to take one second shots with one-second intervals between each. The maximum shot-to-shot delay will be two seconds that way and it doesn’t matter what your exposure length is on the camera if it’s NOT bulb.
What if you want BULB mode? How do you configure that?
Answer: (Select the text below to reveal)
That’s the normal intervalometer configuration mode. Camera is bulb, length of exposure is whatever you need and the interval should either be 1 second, or exposure length PLUS one second depending on the intervalometer.
Another way that I combat the gaps…as long as you keep your shutter below 30sec. Lock the intervalometer release down, and set your camera on high continuous shutter release (Ch). Nikons, you will have to use the timer portion of the intervalometer…and set the max continuous shutter release to 100. You will have to work out the times, for the amount of seconds, for example one with 30 second shots, you set your time on the intervalometer to 45 min, with the 1 second gap, and the amount of shots to 10 or so…that would be up to 450 minutes of 30 second shots…Lots of shots. 😀 the only time that doesn’t work is if you need to go above 30 sec.
Steve, did you know that your camera introduces MORE time between exposures in that mode? I haven’t tested my D600 just yet, but every camera I have tried takes 32+ seconds to take 30 second exposures.
See this old article for details.
http://starcircleacademy.com/2010/07/how-long-does-a-30-second-exposure-take/
Also, on Flickr there are lots of people who have posted their test results.
The other significant problem with the “lock down” approach on the Nikon is that it stops after 100 exposures and that can’t be prevented.
Put your nikon camera on Ch mode and hold down the shutter button…I don’t know what it is on a Canon but its there. On my D800 the speed is 5 frames/sec…1/20th sec. On the D4, I think it’s 10-12/sec….it is using the fast continous shutter release…like sports and wedding photographers…sometimes referred to as “spray and pray.” The only difference is that instead of shutter times of 1/2000 sec, it is 20-30 sec. The only thing you have to remember to do on Nikons is to change that menu setting and adjust your intervalometer time. Canon I do not think has the restriction. Your buffer never fills up because it is long enough between the shots to save to the card.
At the absolute most, it is a second between frames.
Steve: Please run the tests yourself (http://www.flickr.com/groups/startrails/discuss/72157625051118207). Don’t go by the sound. Judging by the SOUND it does seem very fast, but the sound doesn’t tell the whole story. Judge by the recorded data and your stop watch. The frame rate of the camera seems to be completely irrelevant for this scenario. If your D4 really does have inter-frame delays of less than 2 seconds at 30″ exposures I’ll be quite surprised (and please post your results at the link I gave earlier).
If you want to take it even one step further, try those shots with the night sky. The earth’s rate of rotation being constant you can measure the actual gap between star trails (again as shown in the above link).
My test results with the Nikon D600 were consistent with every other camera I’ve tested. The Nikon was slightly faster with a total 30″ shot time of 32.2 seconds rather than 32.6. That is to say there are 2.2 seconds between exposures of 30″.
I have been doing trails since the winter of 09 (Not as long as you, I know 😉 ) and have tried all but the newer wireless intervalometers…
As far as the trials. Using the camera’s recorded times…and Lr’s metadata times, (Using a stopwatch you have to include your reaction time) I am getting consistant 30 sec exposures with 2 seconds between with the Ch. With the wired intervalometer, the exposures are 29.7-29.9 sec exposures and 1.4-1.5 sec in between…really close and when expanded out the 4 frames gets you near that time that you were getting…(Lr says that the exposures are 30 seconds, but the camera, says they are 29.7-29.9…I go with the camera since Lr probably rounds up. the clock times however, in both the camera and Lr are the same…Lr also has the hundredths of a second in the metadata. ) So going by your experiment…except I only shoot RAW, It looks like the intervalometer may be better…I don’t really see much of a difference in times when you add the .3-.1 seconds back in.
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HOWEVER
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Curiously with 20 sec exposures (Which is where I set my camera when I am shooting the star part of the star trail because of the amount of light pollution I have) the gap is only .4 seconds in between. ith the intervalometer, the shutter times are 19.7-19.9 seconds and 1.1-1 sec in between. This would explain why I am getting tighter trails at 20 sec using CH as opposed to using the intervalometer at either 20 or 30 sec.
It looks like the only way that I am going to be able to get a real idea of which is better, is to make mini-trails of each and compare. It looks like I might have a clear night tonight, so I will take ten shots each of all four and create a mini-trail of each. I will set up looking east or west so that I can get the maximum gap. I will be using my D800 and a 16mm f4. ISO will have to wait for nightfall…but I am thinking it will be 800….but that is after work ends at 2 so I will have to get back with you on that at some point. 😀
To get the best idea, use a telephoto lens in your trials. Then you’ll be able to see the actual gaps in pixel terms.
As you discovered, the amount of “dead time” between exposures does seem to vary according to the exposure time – which makes no sense to me. In one of those articles I previously posted, there is a comparison of 15, 20 and 30″ exposures.
Okies, First thing I didn’t get the reply suggesting the telephoto till after I had left, so I will have to do the telephoto maybe tonight. Second I do not like pixel peeping…so I would never do such a major crop in a finished picture.
As far as doing the test I had described earlier…I did both 20 and 30 seconds and the results were similar…well the 20 second one was tighter, so it is harder to see the gaps,and the differences in length were not as noticeable, which I had sort of expected.
But the 30 second trial showed some real differences.
First, using the Intervalometer for the shutter time created shorter star trails…which is kind of what I had expected due to the times I was getting yesterday.
Second, even though it was minimal (we are talking about .4 sec per frame here) the Ch appeared more smooth especially in the brighter stars. There still was a gap…but it was really tight.
Here is a side by side of both in one picture zoomed into about 100%. as well as a 300% zoom. The CH was taken first facing west and then the Intervalometer controlled one…about five minutes after the first…intervalometer battery issues kept me from doing it right after the first…so I did the 20 sec Ch series while I looked for my spare batteries.
100%:
http://i153.photobucket.com/albums/s226/sjlarue/SCA/Capturestars2_zps0bedd3cc.jpg
300%:
I think the Ch method is going to have to come down to the camera…my D300 is slower than my D800…so it may have wider gaps, and I would probably have the intervalometer control the shutter…I wish I had the D4 to try it out on. If it is still clear tonight, I will brave the graveyard and try some more with the tele. Just for fun.
Good sleuthing. Much appreciated. Just to be clear, both the Intervalometer and Ch “held down” exposures were 20 seconds, right?
Good that you pointed west where the angular speed is the greatest. I’m going to test with my 770mm lens tonight then the gaps should be very evident.
And I agree that pixel peeping doesn’t help, but it sure is nice to know how to minimize the gaps. You never know when you’ll have to crop and make an image large.
First off, I am going to have to take my telephoto out more…that was fun. After taking the ones for the trial, I sat out for another half hour trying to get the Orion nebula…
The ones above are 30 seconds…the 20 seconds were too tight to see any difference.
Here is ones I did last night, they are @110mm and 20 seconds x 9 frames.:
w/Intervalometer
w/Ch…and an accidental bump…even though I was no where near it, and I was in the graveyard..alone…spooky…:
On the bright stars, and the dark stars, they look about the same, even though the Ch ones are longer…The middle brightness stars show the difference better I felt.
Walker asked:
Q: How Do I take “HDR” (auto bracketing) using an Intervalometer?
A: The one-second interval trick above works well, but another trick is to set the camera to bracketing mode, add a 2 second self timer delay. On all of my Canon’s the 2 second self timer delay causes the entire bracket to occur after the timer. Another method – a bit more dangerous when using a intervalometer is to set the camera to “continuous exposure” mode. On Canons and Nikons in continuous exposure mode as long as the shutter button is held down, the camera will shoot each of the bracket shots and STOP when the last bracket is completed. You have to release the shutter button to start the next exposure sequence. To make the intervalometer behave just as you would by hand set the intervalometer “exposure time” at least one second longer than the total time for all your shots in the bracket PLUS the self timer time (if that is also enabled). BE CAREFUL with continuous exposure mode… if you forget to turn on bracketing, you’ll get a lot more shots than you probably want!
Thank you, I will use it tonight with the lunar eclipse and see if I can stack the whole sequence from start to finish.
Can i use intervalometer to engage continuous shooting (setting continuous with speed ~5fps on camera instead of bulb) for 20 seconds and delay/timer of few minutes ? (with sony a6000)
(continuous drive on camera and set shutter time =20sec on intervalometer, it should force continuous shooting for 20 seconds, right ? (are there any other limitations i’m not aware of?) )
We notice you posted this question in two places. Intervalometers really only do two things: press, or release the shutter button. Therefore an intervalometer can duplicate anything you can do with one finger on the shutter button. 5fps x 20 seconds = 100 images. I doubt many (if any) cameras can sustain a burst that long. On the other hand, you’d have to be shooting with an exposure of 1/20 of a second or less to get 5 frames per second. This is all a round-about way to say that in theory you could provoke 20 second “bursts” but it is very likely frame buffering (or card writing speed) will prevent it from doing what you’d like.
As we always say: can’t hurt to try to see what you do get.