In this video and article we’ll cover what shutter speeds and shutter angles are, how the shutter speed or shutter angle can be used to control motion and exposure, and which settings to use to get the “film look”.
First, here’s the video:
What is a shutter?
A camera shutter is a device that lets light through for a brief duration. If the aperture controls the area through which light can pass, the shutter controls the time period over which light can pass.
This means, the longer the shutter stays open, the more light passes.
A fast shutter speed means the shutter opens and closes quickly, and only a small fraction of light is allowed to pass through. A slow shutter speed means the shutter stays open longer, which allows more light to pass through.
Understanding the Shutter Speed
Traditionally, still camera shutter speeds are expressed in ‘seconds’, at fixed intervals. The difference between the shutter speed and amount of light is directly linear; which means, double the speed, double the light – or half the speed, half the light.
Here are the standard shutter speeds you’ll find on most professional cameras (in seconds):
1/2000 – 1/1000 – 1/500 – 1/250 – 1/125 – 1/60 – 1/30 – 1/15 – 1/8 – 1/4 – 1/2 – 1 – 2 – 4 – 8 – 15 – 30 – 60 – 125 – 250 – 500 – 1000 – 2000
These are not the only shutter speeds possible. Professional cameras allow you many values in between, for greater light control. The only thing you have to remember is, every time you double or halve the shutter speed, you are doing the same to the amount of light it lets through.
Types of Shutters
There are many kinds of ways you can block light coming through your window, and shutter technology is no different. The most popular shutter types are:
- Focal-plane shutters – found on DSLRs (shutter is close to the focal plane or sensor, hence the name)
- Electronic shutters – found on video cameras (no physical shutter, just that data is read out at time intervals)
- Leaf shutters – found on medium and large format camera lenses (each lens has its own shutter!)
- Rotating disc – found on 35mm movie film cameras
- Your hand – use a lens cap, similar to pinhole photography
When it comes to video, you only have to worry about electronic shutters and rotating discs. Electronic shutters follow the shutter speed system explained above. Rotating discs have their own version.
The Shutter Angle
The simplest type of rotating disc shutter is a semi-circular one, like the one shown above. It has only one ‘shutter speed’ setting. Obviously, you need some method to control the time duration.
For this reason, rotary discs in movie cameras can adjust the shape of the shutter, like this:
Instead of shutter speeds in seconds, rotating disc shutters use shutter angles. The larger the shutter angle, the more the light passes through. The relationship is designed to be similar to shutter speeds – halving or doubling the angle will halve or double the light.
Most film movie cameras have shutter angles from 0o to 180o. The most common shutter angle used is 180o, which gives us the ‘film look’ (Remember, it’s not the most special, it’s simply the most common). This corresponds to exactly half the duration that each frame will take in one second.
E.g., if a movie is shot at 24 frames a second, each frame takes about 0.0417 seconds. A 180o shutter will let light pass through for half this time period, which equates to 0.0208 seconds, which is roughly 1/48 seconds.
Therefore, a 180o shutter angle is similar to using a shutter speed of 1/(2*frame rate) seconds. When cameras don’t allow you to choose 1/48s exactly, you can approximate the same effect with a shutter speed of 1/50s – for 24 fps.
Want a simple formula to know the relationship between Shutter Angle (A in degrees), the Shutter Speed (S in seconds) and the frame rate (F in fps)? Here you go:
S = A/(F*360)
High frame-rate (HFR) shooting
Why does it take a lot more light for high frame rate (HFR) shooting? Imagine shooting at 1000 fps. The shutter speed you’ll probably use is 1/2000 seconds – that’s more than ten times the light required!
If you were shooting at an ISO of 100 at 1/50s, then you’ll need to boost your ISO to 102400 to get the same exposure! Now imagine shooting at 1 million frames per second. Only the sun can light something like this on a budget.
Should you stick to the “formula”?
No. As I’ve mentioned in the video, you can start with the formula for shutter speed and frame rate:
Shutter Speed for film look = 1/(2xFrame Rate)
However, to advance in cinematography, you must learn to experiment with different shutter speeds/shutter angles to achieve different effects. The factors that influence the choice of shutter speeds are:
- Electrical frequency
- Frame rate
- Limitations of the camera electronic shutter
- Motion blur
When you can learn how to control shutter speeds, you’ll be well on your way to cinematography mastery. If you have any questions or comments, please feel free to let me know in the comments below.