It's time for another installment in the Exposure series, today we'll be discussing shutter speed. Before you continue, be sure to read the first installment, as I'll be referencing how aperture relates to shutter speed. You can find the first part here: Exposure Part One: The Almighty Aperture . Now that that's out of the way, let's get started!
On A Wing...
Shutter speed is the physical speed that your camera opens and exposes its sensor to light. Your camera has a small curtain that lifts when you press the shutter button and closes after a determinate amount of time. Shutter speed is measured in fractions of a second, with most cameras achieving 1/4000th of a second on the fastest end, all the way down to 30 seconds on the slowest end. There's even a way to leave the shutter open for as long as you need, called "Bulb", but we won't get into that today. Most photography will stay within the fractional range, not extending to slower than even 1/30th of a second. When you're outside, you'll find yourself using faster shutter speeds, and slower for indoors shooting. Knowing the proper settings for indoor and outdoor subjects is an important part of good exposure, but knowing when to break the rules is important to finding your voice.
In Motion.
As with aperture, shutter speed has an effect on controlling exposure, but that's not necessarily its intent. Shutter speed is a way to either stop motion, or artistically show motion. When you first start learning photography, you want to adjust your shutter speed so it's fast enough to not capture any motion blur, but slow enough to achieve ideal exposure. Let unpack that term, motion blur; it is blur that appears on your image for one of two reasons. First, if you're taking photos of a living subject, like a model or an animal, small unintentional movements will be picked up at slower shutter speeds. Second, when you hold the camera in your hand, no matter how steady you are, it will pick up your own movement at slow enough shutter speeds. The latter instance is where a tripod comes in handy.
Velocipede.
The relationship between shutter speed and aperture is easy to learn, but difficult to master. One tool that every camera has is the light meter, a built in calculator that determines what the best settings to use in relation to achieve proper exposure. When you look through your viewfinder, you'll see a set of tick marks, with one that moves left or right when you change aperture or shutter speed. The goal is to get the tick mark in the middle, not too far on either side. If your shutter speed is too fast, your photo will come out too dark, underexposed. If your shutter speed is too slow, your photo will come out too bright, overexposed. Most of the time, it's that simple. When you're outside on a sunny day, taking photos of flowers with your aperture at f2.8, your light meter will tell you that your shutter speed should be fast, something like 1/1000. Now, if you change your f-stop to f5.6, you'll notice at shutter speed 1/1000, the exposure is darker. This is how the aperture and shutter speed work together, I like to think of it as a balancing act. As your aperture closes up, you're letting less light in, so how do you compensate? You slow down your shutter speed, allowing more light in over time. You could say it's the relationship of space and time, aperture lets more light to hit the sensor by allowing more coverage, and shutter lets more light in by allowing more time.
Like the movies!
So how to you use aperture and shutter speed together artistically? Well, that's entirely up to you! Think about the relationship, and what you want to show with your image. If you're doing street photography, you might want to keep a relatively broad depth of field, but you want a quick shutter speed so your subject isn't blurry. Same goes for sports photography, if you want to get the moment that foot meets football, focus on having a faster shutter speed, and if your exposure is still too dark, open up the aperture to compensate. If you want to show motion blur, like the above Star Wars reenactment, you'll want to slow your shutter speed to get the cool light trail effect. You'll notice though, that if you're trying to achieve a motion blur effect during the day, your image will only become brighter and brighter as you slow your shutter speed. The best way to compensate is to simply close your aperture, thus darkening your exposure. This is how the balance works, if your exposure is too bright but you want to retain your shutter speed, change your aperture. Same goes for if your exposure is too dark, open the aperture to get more light hitting the sensor. Keeping in mind this balance will help you immensely, especially when your vision calls for certain settings, but your exposure just isn't what you want it to be.
Too slow!
I hope this installment was helpful, stay tuned for next week, where I'll be explaining ISO, the final pillar of Exposure, and how all three pillars work together to help you create the best photos! Please sound off in the comments if you have any questions, thoughts, comments!