Welcome to part 2 of our Freebie Photography series where we are exploring the Exposure Trifecta. In our first installment, we discussed the aperture of a lens and how it affects both the light through a lens, and the depth of field when adjusted. If you missed it, you can read Part 1 HERE.
Today, we’ll go over the second of our three primary exposure functions, our shutter speed.
Controlling your shutter speed is probably the easiest of the Exposure Trifecta to understand, possibly one of the first functions we venture off of our full auto mode to try our hand at, and a tool that if used effectively can either freeze action, or allow movement in your scene. Playing with shutter speed can provide some fun results, and depending on your desired outcome, can produce drastically different images.
FREEBIE PHOTOGRAPHY 101 – THE EXPOSURE TRIFECTA, PART 2 – SHUTTER SPEED
Just as we went through explaining aperture, we’ll dive into shutter speed here. When controlling your aperture, shutter speed and your ISO, you can change how a singular subject, or scene is rendered in your final image. When a camera makes these decisions in Auto Mode, you lose the ability to control them. Sometimes it’s easier to let the camera make these decisions for us, but other times we are better served by taking the control. These articles are aiming to help those of us who are interested in understanding why and how to manipulate these functions to better control the resulting image.
Shutter speed is the amount of time that a shutter is opened, allowing light to fall on a sensor or film. It can be measured in fractions of a second through multiple seconds or even many minutes. The shorter (or faster) the shutter speed, the less time that a sensor, or film is exposed to the light coming through the lens. Of course, the longer (or slower) the shutter speed, the more time a sensor or film is exposed to light.
While there are applications where 60 second or longer exposures are called for, most of the time, we’re working with fractions of a second, and we can adjust these, similar to the way we adjust our aperture, in stops. Where an aperture stop is a calculated measurement of the diameter in relation to the focal length with each stop halving or doubling the amount of light let through a lens, a shutter speed stop is a half or doubling of the amount of time the shutter stays open which also halves or doubles the amount of light in a given exposure respectively. Below are a few examples of shutter speed settings in full stops.
1 sec – 1/2 sec – 1/4 sec – 1/8 sec – 1/15 sec – 1/30 sec – 1/60 sec – 1/125 sec – 1/250 sec – 1/500 sec – 1/1000 sec
You’ll notice that a few of our stops aren’t ‘exact’ doubles or halves of the former or latter like 1/8 to 1/15, or 1/60 to 1/125. This is a rounding to keep things somewhat tidy and while actual measured shutter speeds may be slightly different than their listed measurement, this is how it has always been in photography. To add to that, most every modern camera can adjust in between these full stops to 1/2 or 1/3 stops which puts one or two more shutter speed settings in between each of the full stops.
Simply put, a stop is a stop. If you achieve proper exposure with your aperture set to X and your shutter speed to Y, you’d get the same amount of light if you were to adjust each of those in equal increments in opposite directions, like X -1 stop and Y +1 stop.
Here are two pictures showing two identical exposures mathematically, but resulting in two different final images.
Both exposures above have allowed the same amount of light to hit the sensor by way of regulating it via the aperture and shutter speed. I adjusted my aperture and shutter speed equally in opposite directions, to get two different effects. Both of these shots were taken using a wide angle lens with my camera on a tripod. If handholding, I’d feel comfortable doing so with the first setting, while being able to stay steady for 1.3 seconds might be a much harder task.
The first image uses a reasonably “fast” shutter speed of 1/80 of a second. Handholding a shutter speed like this, with a wide angle lens as was used, normally allows for a decent “freezing” of mild movement or action. There is certainly still a blurring of movement at this shutter speed, but the water is more recognizable as cascading clumps as opposed to the silky effect in the second, slower shutter speed example. One of these shots (the faster shutter speed) would be pretty easy to handhold while the second would be far more difficult. This is where something like a tripod will come in handy if wanting to use longer shutter speeds.
Adjusting my shutter speed by 6 1/2 stops (1/80 – 1/40 – 1/20 – 1/10 – 1/5 – 1/2.5 – 1/1.3 – 1.3sec) forced my camera to adjust my aperture by 6 1/2 stops as well (f/1.7 – f/2 – f/2.8 – f/4 – f/5.6 – f/8 – f/11 – f/16) ultimately achieving the same exposure.
While I didn’t test my ability to zen out by keeping a 1.3 second exposure steady while handholding, we can see an immediate difference when shutter speed is altered for a subject with dynamic movement like a waterfall. This same effect can be seen when shooting anything that moves within reason and a slowed shutter speed can add movement inside an otherwise static scene.
As a widely accepted rule of thumb, to account for handshake or photographer based movement when handholding your camera, use the 1 over the effective focal length rule where you want to keep your shutter speed at or faster in fractions of a second to that of your effective focal length. Using this rule of thumb, if shooting a 50mm lens on a full frame camera, 1/50 second is as slow as you’d want to go to overcome your handshake which will normally result in an acceptably sharp image, of any static elements anyway.
I say “effective” focal length because when shooting a particular focal length on a smaller sensor, it crops into the image which effectively multiplies to a field of view of a longer focal length. If you’ve heard the term “crop factor” this is what is being described. To achieve the “effective” focal length, multiply your actual focal length (this is a physical measurement and is the same regardless of any crop factor) by your crop factor. For instance that 50mm lens on a m4/3 camera would effectively crop to an equivalent 100mm lens. Crop factors for popular formats are as follows:
- 1″ sensor (Nikon 1 series, Sony RX100, Canon G7X, etc) 2.8x crop factor (I round to 3x)
- 4/3 sensor (4/3 or micro 4/3 system) 2x crop factor
- APS-C sensor (Sony, Pentax, Nikon = 1.5x crop factor – Canon = 1.6x crop factor)
This is not to say that we cannot get sharp results when using slower shutter speeds, and depending on technique, often aided by some type of optical or sensor based image stabilization, we can decrease the shutter speed with a decent result. Keep in mind though that nothing can account for subject movement other than freezing that movement by way of a fast enough shutter speed, or added flash when you’re allowing the flash to dictate the exposure by overcoming the ambient light involved in any given scene. If you’re adding flash and balancing this with existing light, you can see ghosting if your shutter speed is on the slower side, where your subject movement is still recorded in the image around a sharp “frozen” subject which has been lit by the flash.
We discussed the 1 over the effective focal length rule, which is about as slow as one would want to go to combat hand shake or camera movement, but what about freezing subject movement? There are no hard, fast rules but if wanting to freeze a quickly moving subject, shutter speeds above 1/1000 second are often called for. Keep in mind that if a subject is moving across your scene laterally, you will need a faster shutter speed to freeze movement then if your subject is moving toward or away from you. Of course, if your subject is moving toward or away from you, you will also need to keep an eye on your focus as that movement may take them outside of your depth of field, or challenge your camera’s auto focus system beyond its ability.
I would say that in my experience, if I were shooting the same subject from two different angles (one which would put its movement across my field of view versus one where it moves toward or away from me) I need to at least double my shutter speed to freeze its movement when traveling laterally versus vertically toward or away from me. If I’m shooting a fast moving car zipping by me, that shutter speed may need to be 1/4000 sec where I would normally be able to get away with 1/2000 second if that same car, traveling that same speed were to be coming toward me. Again, this is not a hard rule, and further complicated by the velocity and direction of movement coupled with our working depth of field or even our, or our camera’s ability to keep up with focusing, but movement tends to be far more pronounced when moving across your frame.
Let’s do a simple experiment with handholding to gain a decent understanding on our personal thresholds to keep an image sharp.
- Set your camera to your Shutter Priority mode on the mode dial. Normally designated by an S, Sp, T or Tv (shutter or time priority/value). This will allow us to change our shutter speed while the camera adjusts the other necessary components for a proper exposure. Check your camera manual if you’re not sure how to do this.
- Using a singular focal length (set a zoom lens to one focal length and stick there for this exercise), start off with a shutter speed at that 1/effective focal length. If you’re using a 1″ sensor camera, take the focal length and multiply by 3x, if using a micro 4/3 sensor camera multiply by 2x and if using an APS-C camera multiply by 1.5x (if you’re shooting with a FF camera keep it to 1/focal length).
- Choose a static subject (don’t shoot outside where wind could affect our subject movement) and try to stay in one spot while going though this exercise. Take a shot.
- Now, adjust your shutter speed in 1 stop increments with each shot using a longer and longer shutter speed until you notice that your hand shake has negatively affected the sharpness of your shots.
I shot using a micro 4/3 camera and a 75mm lens (2x crop factor making for a 150mm equivalent focal length), neither of which provided me with any type of image stabilization. My first shot, which was pretty sharp was taken at 1/160 second. To spare you the boredom, I’ve skipped a shot between each, showing two stops difference going from 1/160sec to 1/40sec to 1/10sec. The 1/40 second shot is not sharp, but still legible. The 1/10 second shot looks like I tried shooting during an earthquake.
- Shutter speed is simply the amount of time the shutter is open, exposing a sensor or film to light traveling through the lens.
- Bright conditions will require a faster shutter speed, while darker conditions will require a slower shutter speed to achieve proper exposure, all other settings being equal.
- Shutter speed can effectively freeze or blur subject motion. Either result may be desired, but when shooting with slower shutter speeds, camera movement or hand shake can more easily affect the sharpness in the final image.
- Shutter speed can compensate for hand shake, or photographer movement, with the commonly accepted rule of thumb of 1/effective focal length where we keep our shutter speed at the equivalent to the focal length measurement (multiplied for any crop factor) for the lens we are using.
- Lens or Sensor based image stabilization can help compensate for hand shake, but will do nothing for subject movement.
There we have it. Round 2 done and dusted. Please feel free to comment below with any questions, observations or personal anecdotes.
Read the other two parts of the Exposure Trifecta:
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Thanks for the read and happy shooting,
Enjoying reading your instructional postings. Never hurts to review things…
Actually I just wanted to comment on your photos of the waterfall. I was quite impressed & surprised with the depth of field you were able to achieve with the 1/80th – F1:7 shot.
Looking forward to your next posting.
Jim Kendall – NBSC
Thank you Jim. Working on it as we speak, er type ;). The reason for the DOF is that I was within my hyper focal distance at f/1.7 with my focus distance probably about 75 feet away. The falls in the foreground alone are 70′ high to give the shot some scale.
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