Electric Films Pty Ltd
Shooting Good Time Lapse - Tips from a Professional
Sometimes I get asked how I shoot Time Lapse, so I'll give you some tips on
how you can create stunning Time Lapse Photography too.
Getting the Bumps out
Obviously use a study tripod for short shoots of a day or so and avoid the
bumps. With big bumps, it is best to change the angle or shot size. Normal
Cinematography rules apply here to avoid a 'Jump Cut'. (A jarring transition
between 2 similar pictures)
If you have shot enough vision, go for a Close Up and then come back to a
Wide shot to finish off. Keep the shot's Ratio 'time' length pleasing. Like
5sec/5sec/5sec. or 10sec/5sec/10sec etc.
Removing the bumps in
After Effects - Before and after
Stretching
shots to match
You can take quite a large amount of movement out of your shots by using Adobe
After Effects. They have a great filter for automatic motion stabilization
called Warp Stabilizer. For bigger movements, it's best to pre edit the shot
before stabilization by using their 'Corner Pin' filter first. You can stretch
and match varying shots which can fix a large amount of movement.
You start at one corner and work your way around to each corner stretching the vision to match. You do this several times. Obviously put the shot in above the other at 50% opaque.
You can also lay over still image of the average position you are trying to match.
Time Lapse Exposure Time
Motion pictures run at 50% exposure and 50% of nothing. This 'nothing' is
from film camera days when the shutter was blocking the exposure as the Camera
moved the film down to the next frame ready for another exposure. This pause
in motion helps our eyes to perceive still images as motion pictures.
Before sound the Cameras ran at 16 to 18fps. A telecine machine (converts film to Video) runs at 24/25fps so that's why early silent pictures run fast. With the introduction of sound the Cameras where speed up to 24fps to improve the sound quality.
Time Lapse Cameras run even slower from 1 frame a second to 1 frame every 10 minutes etc. Most of my Construction Time Lapse Videos on this site were shot at 1 frame every 10 minutes. (I actually shoot HDR, 3 frames together, one frame 2 stops under exposed, one normal and one frame 2 stops over.
Great results can be achieved when shooting fast moving subjects with a one second exposure.
On Construction Sites, if you are shooting at 1 frame every 10 minutes, that works out at 6 frames per hour and 72 frames per day or 2.9 seconds. (72 frames divided by 25)
30 days = 2,160 frames (72 frames x 30) or 86 seconds or 1.4 minutes. So using this formula you can calculate the length of any shot.
An easy way to do it is say to yourself and your calculator that I have 1 hour of time to play with and to make a shot. So pick a number like "I'll try shooting 1 frame every 10 seconds" and see where this comes out at. Shooting 1 frame every 10 seconds = 6 frames a minute which is 360 shots per hour. (6 frames x 60 minutes = 360 shots) Divided that by 25fps playback and you get a 14 second shot.
When you have done that calculation you can put the hard Maths away and do the rest in your head. You calculated above that by shooting 1 frame every 10 seconds would give a shot of 14 seconds in 1 hour of your time. So shooting 1 shot every 20 seconds will now give you a 7 second shot. Easy.
You can also get pleasing results running your shots back at 50% or 75% speed.
I like the 75% playback as it gives a slightly slower motion to you shots.
At 50% or 12 fps it is too jerky.
Advanced Exposure Times
If you want to see the moon's detail at night,
which is lit by the sun and also see detail in your subject which is lit by
Moonlight in the same shot, you'll need a pretty big exposure range. I've
done this before and you need a camera that can shoot a large range of exposures
like a Canon 5D and a fair amount of trial and error and mathematical calculations
to get all the exposures in the Camera before the next time frame interval
you have set the intervalometer at.
Ideally when shooting Time Lapse the 50% of exposure and 50% of nothing will give you a beautiful blurring effect on the motion while keeping static objects static. A heavy amount of ND filters are required to achieve this. As Time Lapse is usually shot at a high ratio and that is why it is staccato looking. Let's work it out at 1 frame shot every 10 minutes Without any ND (Neutral Density) filters you would be shooting outside at, say 1/200 of a second. 10 minutes is 60 seconds x 10 minutes = 600 seconds.
When you play back the video at the standard 25fps (in Australia) that = 600 x 25 frames. This = 15,000 seconds. So your Time Lapse Camera is running at a ratio 15,000 to 1 and that's if the Camera's exposure is at 1 sec exposure. So shooting at 1/200 of a second it is now 15,000 x 200, which = a ratio of 1 in 3,000,000.
A vast difference from a ratio of 50/50. So the actual exposure to get to a 50/50 ratio would be a very long exposure of 7,500 seconds (15,000 seconds divide by two) Divided that by 60 seconds and you get a 125 minutes exposure time. Rather difficult but achievable if you really tried. But you would have to pick you subjects. This would look good on slow moving subjects like grass growing but you would just have a visual mess if you shot a ball game. This is high end stuff so lets get back to it.
Transitions from Moonlight to Daylight
Now here is a tip for you and my opposition. I like to shoot my exteriors
to capture moonlight and full sun in the same shot. To achieve this set your
Camera on Auto ASA to a maximum of 800 ASA, lens at around F5.6 and Auto Exposure
on your Time settings. Depending on how dark your night exterior is you might
need to open up a little. A bit of testing here especially if you are shooting
HDR as the daylight overexposure shot comes close to 1/4000 sec which some
Cameras can't do. Shooting just a single exposure you'll be fine.
I also shoot on Automatic exposure because there is a large exposure range if you want to go from night to day or Sunrise to Midday or if it's cloudy.
HDR does help here a little as the rendering process tends to smooth out the exposures. Also make sure the lens F stop is fixed and it's the time that varies. If you have the F stop varying you get a weird effect with depth of field changing.
I use the Vello Shutter Boss or the Canon Intervalometer for Camera control (The batteries really last for 2 years of more) and SNSHDR Pro for my HDR. Then After Effects to turn the stills into movies and Premiere for any finishing if needed.
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Electric Films Pty Ltd
0411 82 7799
Level 11 / 65 York St Sydney Australia
SYDNEY AUSTRALIA