In a previous post, I spoke about the aperture. Now, I’d like to talk about the other half of the exposure dynamic duo, shutter speed. Whereas aperture had everything to do with the lens, nothing to do with the camera. Shutter speed is the opposite. It has everything to do with the camera, nothing to do with the lens. OK, view camera boys, back off! I’m talking SLRs!
But first, I have to answer a question: Yes? You in the back! … *groan* No, shutter speed has nothing to do with wind velocity, hurricanes, or wooden shutters! Sheesh!
A major disadvantage of some of the point and shoot camera crowd is a lack of ability to control the shutter speed or aperture. Basically, you get what the camera gives you. The camera works to get you a clear picture where everything is in crystal-clear focus. But, what if that is not what you want?
Blurring on purpose? Absurd!!!
The above picture, my son’s basketball team running ‘suicides’, was done using a method called panning. You hold the camera at eye-level and rotate at the waist while following the action. You need to use a slow shutter speed, in this case 1/8 of a second, in order to get the blurred effect. This effect gives the picture a sense of motion.
What is shutter speed?
Shutter speed is the amount of time expressed in seconds, or fractions of seconds, that the shutter curtain is open and allowing light to fall upon the sensor or film. My Nikon D300 has shutter speeds ranging from 30 seconds, on the long end, all the way up to 1/8000 second, on the high end. There is even a ‘bulb’ setting that allows you to hold the shutter open for as long as you want. This can make for some interesting night shots. Exposure = quantity (aperture) + time (shutter speed).
Fast shutter speeds
Higher shutters speeds, generally speaking, are about 1/250 second or greater. Higher shutter speeds allow you to freeze action. This comes in very handy when you are shooting sports, or some other fast paced action that you’d like to freeze. You can capture a moment in time, like the picture of this diver to the right, at the point of no return. Notice how the water droplets at the bottom of his shorts are frozen in time.
Slow shutter speeds
Slower shutter speeds allow you to capture motion over time. It gives your image an overall artistic feel. My favorite motion studies are of water. I like to set my camera upon the tripod and expose an image for multiple seconds. Of course, you have to have a fairly low light level to do this, or a filter that reduces the amount of light coming in so as not to overexpose (let in too much light) the picture. In this photo, to the left, the shutter has been left open for about 20 seconds. Everything that is stationary, rocks, plants, etc. remains in sharp focus. That which is moving, the water, takes on a pleasant blurred effect. This type of shot can only be accomplished by using a steady tripod, or some type of camera support.
Without a tripod, save for panning, slow shutter speeds can be a disadvantage because they record camera shake. You may have the hands of a surgeon, but surely you cannot hold perfectly still. Your breathing, heartbeat, and nervous system all contribute to camera shake. Additionally, where you stand, how you stand, the wind, etc. make their own contributions to this vibration. Lenses with image stabilization help to reduce this vibration, but are no substitute for a good tripod, but that’s another article all together.
It’s rather difficult to get sharp, hand-held pictures at the lower shutter speeds. A rule of thumb for selecting a shutter speed is that you shouldn’t shoot at speeds less than 1/focal length. So, if you have a 50mm lens, then don’t hand hold at less that 1/50 second. The longer the lens, the higher the needed shutter speed. A 500mm lens would require at least 1/500 of a second. Personally, I like to double that number, and prefer not to hand hold under 1/(2 * focal length). Mind you, only a very small percentage of my shots are taken hand held, save for sports.
Well, I cannot beat this horse anymore. So, I’ll just have to get another one ride off into the sunset. Until next time! (No horses were harmed in the making of this post!)