What is Shutter Speed in Photography?
Shutter speed is like the eyelid of the camera, and in ancient times, it used to be outside the camera only, just like the eyelids. It is one of the three pillars of exposure in photography – Aperture and ISO being the other two.
Shutter speed controls the duration of time in which light enters the sensor or film.
Shutter – The Eyelids – The Simple Explanation
Have you ever wondered why we don’t blink our eyes much when in the dark and stay still for some time till we start seeing parts of the scene in front?
Because of the lack of light, your eyes are creating a long exposure by not blinking, so that the image can be formed on the brain – the sensor.
The Shutter is like the eyelids of the camera, and the speed at which eyes blink is thus the shutter speed.
Learn more: Photography Courses – Best Online Classes
Camera Shutter – The Terminology
Shutter, as a mechanism, has evolved much in the past few years to come to its present form of an electronic shutter. Some of the earlier systems were simply based on clockwork.
Button was clicked to open the shutter, and again to close the shutter. It was the only way in the earlier years of photography and had problems with consistency.
Bulb mode, which is there even now, involved shutter being open as long as the button was pressed. An instantaneous exposure was also there with settings ranging from 30” to 1/4000 where the best leaf shutters were involved.
From the 20th century onwards, electronic shutters have been more common, and the mechanism is high evolved now.
Types of Shutters on SLR, DSLR and Mirrorless Cameras
There are two types of shutter mechanisms, behind-the-lens, and in-front-of-the-lens mechanisms. Most of the present-day mechanisms are behind the lens, usually built inside the camera body.
The front mechanisms sometimes were simply camera lid added over the lens, which was opened and closed. Some of the common shutter mechanisms before the electronic shutter came were:
Focal Plane Shutter
Usually implemented as a pair of light-tight cloth, metal, or plastic curtains placed just ahead of the film in the focal plane. They had the advantage because the lenses could be changed.
Simple Leaf Shutter
These involve single or two leaves that are in front of the lens. When triggered, they open to allow the film to be exposed, before closing again.
A kind of rotating shutter which had a part of the sphere integrated behind the lens.
A number of thin blades that open for exposing the pictures. It is very similar to aperture itself, and hence has all the problems related to aperture, like a vignette, etc.
The DSLR and Mirrorless Shutters
In the DSLRs, there are three systems combining to form shutter – mirror box, front curtain, and rear curtain. What you see through the viewfinder is what comes through the mirror box.
On clicking shutter, or in live view mode, the mirror gets up, and nothing is visible in the viewfinder. When we press the shutter button, the first curtain or the front curtain opens up the sensor, making it exposed to the light.
The second curtain or the rear curtain follows after the time is complete to close the shutter.
The time during which the sensor is exposed when the first curtain has fallen but the second curtain hasn’t, is called the shutter speed. It is the time duration during which the shutter is open, and the sensor or film is exposed to light.
A small difference in mirrorless cameras is that there’s no mirror box or mirror system. Hence, the viewfinder is electronic, and the LCD or viewfinder gets an electronic image, which usually has a slight lag. The curtain system works exactly as in DSLRs.
Shutter Speed Measurements and Stops
Shutter speed is measured regarding a fraction of seconds and seconds, depending upon the length of the exposure. It is usually expressed in fractions of seconds for exposure less than a second. After that, it is expressed in seconds.
The stops in shutter speed go like:
1/8000 1/4000 1/2000 1/1000 1/500 1/250 1/125 1/60 1/30 1/15 1/8 ¼ ½ 1 2 4 8 15 30
*Image by Daniel Peters / Photoblog
Each stop of light moving from left to right opens the shutter for double the amount of time than the previous, allowing for double the exposure.
Each value is double the previous one (or half, going from right to left). A minor variation comes in the form of 1/125 to 1/60, 1/15 to 1/8, 8 to 15, and so on, which are not perfect halves or doubles but nearly.
It is assumed to maintain numbers in a way in which they don’t go into further fractions. For example, half of 1/125 will be 1/62.5 or 2/125, which will be awkward.
Settings the Shutter Speed
There are four different camera modes professionals use. Program Auto, Aperture Priority, Shutter Priority, and Manual Mode are these modes. In Program Auto, you can only select the set of settings and shift between them, while also selecting exposure compensation if needed.
Therefore, if you have an exposure reading coming at 1/125 at f4 and you want a faster aperture, you will get the same at 1/250 and f2.8 (of course if the lens supports this wide aperture).
In Aperture Priority Mode, you can set the aperture as per your requirement, while shutter speed gets automatically calculated. The same is the case with Shutter Priority Mode wherein you dial in the shutter speed while the aperture gets calculated automatically.
All these calculations are based on camera metering, and it is important to understand and use the metering modes correctly. In Manual mode, each of the settings is manually dialed, as suggested. This is a slower and more precise approach, which can ensure the perfect exposure if used properly.
Shake-Blur and Minimum Shutter Speed Rule
Shake-blur is the blur introduced because of the hand movements while taking a shot. There is a simple way to avoid that blur, and it is by using the minimum shutter speed rule.
The rule states that to avoid shake, the minimum shutter speed should be either 1/100 or 1/focal length x crop factor – whichever is faster. Therefore, for an 85mm lens on a full-frame body, the minimum shutter speed should be 1/100 (faster than 1/50).
The same lens on a crop body will have a minimum shutter speed of 1/127.5 or 1/150 because there’s no stop as 1/127.5 and we look for the next possible value (faster than 1/100).
Creative Usage of Shutter Speed – a Few Applications
Some of the applications of shutter speed are:
Star Trails Photography
It is based on the speed of rotation of the earth and the movement of stars. While not visible to naked eyes, we know that the maximum shutter speed for Milky Way photography is 500/focal length (x crop factor – if any). It is also known as the 500 rule.
- For star trails, the reverse is true. You need to have the exposures much longer to form a considerable trail, which are then stacked together to form star trails.
One of the most beautiful applications of slow shutter speed is motion blur. If you shoot a bird while tracking, and have slower shutter speed, the background and the wings will have motion blur – depicting movement.
- The same effect will happen while shooting a dance movement, or a racing event, etc.
Regarding racing events, action sequences, wildlife, etc., we often go for freezing motion. It happens when the shutter speed is faster than the speed of motion.
- For example in certain birds, you may need a shutter speed of 1/2000. In some racing events, you may need a shutter speed faster than that, and you will be able to see the dirt flying and smoke, all frozen at that moment.
This particular photography lets us use shutter speed to the best of our vision. Whether we want smooth motion or frozen motion, we can decide that based on our composition and the idea.
If we have slower shutter speed, it will result in a silky feel to the water. If we have high shutter speed, it will give us a waterfall and a few droplets frozen in its motion.
Using longer exposures, we can get smoother motion in landscapes, nightscapes, etc.
- For example, the motion of the clouds, the water in the sea or river, or simply car trails – all are taken at considerably longer exposures.
Shutter Lag in DSLRs
Shutter lag is the time between hitting the shutter and the time when the front curtain opens up for the image to record.
In modern-day cameras, shutter lag is higher in point-and-shoot and digital cameras, mostly due to the charging of CCD device which triggers the shutter.
It is also because exposure metering and auto-focus take some time. Prosumer level cameras have considerably reduced shutter lag, and it is minimal in high-end DSLRs.
Shutter Speed with Speedlights and Studio Strobes
Speedlights and studio strobes depend on sync speed. It means that shutter speed faster than the sync speed will show a certain portion of the image black. It is the rear curtain that is caught before being closed. Shutter speed usually ranges around 1/200 to 1/160 and is camera-body dependent.
Higher-end models of speedlights and strobes usually have a feature called high-speed sync which lets you shoot at speeds of up to 1/4000. In cameras, there are two options for working with speedlights – front curtain sync and rear curtain sync. These determine the time at which the flash will fire. In front curtain sync – which is the default mode in cameras, the flash fires as soon as the front curtain opens, resulting in sharp images due to the speedlight, and motion isn’t detected.
In read curtain sync, the flash fires when the rear curtain starts to close. What this results in is the recording of motion before the time when flash fires. In places where there is decent ambient light, it can be used creatively to produce some breathtaking images. Images taken by some event photographers fall into this category – which simply let the imaginations fly and use technology to their advantage.
Conclusion on Shutter Speed
Shutter speed is a creative tool, but only when we understand the nuances of how the camera shutter works, and how the light is recorded. Once we’ve done that, we can use shutter speed to tell our stories in the way we want them.
Raghav Gautam His work can be found at raghavgautam.photography.
Further Readings: Photography Courses – Best Online Classes