One of the keys to taking good pictures is to make sure that you allow the right amount of light into your camera. Your camera (whether film or digital) is, in essence, a light-proof box. A picture is taken when you press down on the button and allow the shutter in the lens to open. This allows some light into the box which then hits the film or the digital sensors, creating the picture.
There are two ways to control how much light gets into the camera when you press down on the shutter. The first way is to control wide the opening is. Some lenses allow you to create a very wide opening, while others force you to use a more narrow opening. I discussed one of the effects of choosing the appropriate aperture (that's the fancy word to describe how wide the opening is) in a previous post.
Another way to control the amount of light is to control how long the opening in the lens is kept open. Some high end cameras have a minimum shutter speed of 1/8000 of a second. That means that the lens is kept open for only 1/8000 of a second. My camera's fastest shutter speed is 1/4000. Of course, for some shots, you'll want to use a very quick shutter speed. If you're taking a still picture of Derek Jeter swinging a bat, you'll want a very quick shutter speed, because his bat is moving at high speed. If you hold the lens open for a long time (such as 1/30 of a second), then the bat will appear as a blur.
The shutter speed that you choose for your picture is crucial. The reason is because if you choose a shutter speed that's too quick, you might not get enough light into the camera to make the shot work. If you choose a speed that's too slow, your subject will appear blurry. Even if your subject stands completely still (suppose it's a building), you can still have a blurry subject if your shutter speed is too slow. The reason for this is camera shake.
Most people are unable to keep their hands perfectly still. Hands have a tendency to involuntarily shake. As a result, even if you think you're holding your camera perfectly still, chances are that you are not. Your shaking hands may not make a difference if your shutter speed is 1/4000 of a second (unless your hands shake very quickly!), but at slower shutter speeds, you begin to notice the blur in your pictures. At what point does camera shake start to become an issue? Well, the rule of thumb is that you should never shoot at a speed slower than 1/focal length. So, if you're using a 50mm lens, don't shoot at speeds slower than 1/50 of a second. That means that if you're using a lens with a longer focal length, the effects of camera shake become more pronounced. With a 300mm lens, you shouldn't shoot anything slower than 1/300 of a second.
So, what happens if your lens is opened up as far as it will go, and you still can't get enough light into the picture without shooting slower than the recommended speed? The best solution to this problem is to use a tripod. By using a tripod, you eliminate most of the problems associated with camera shake. Since you're not physically holding the camera anymore, you can now shoot at slower speeds.
While the technical aspects of shutter speed are all fine and well, I suppose you're wondering what you can do with it creatively? Well, there are some things you can do. A few weeks ago, I posted a picture of Grand Central Station. In the picture, I left the shutter open for 30 seconds. During that time, some people moved and some didn't, creating some "ghosts" in the picture.
Another fun thing to do with shutter speeds is to create light trails. I took these two shots on the Brooklyn Bridge last April, shortly after I purchased my camera.
There are two plazas on the bridge where you can stand and walk out over the vehicular traffic that is moving on the bridge. I didn't have my tripod with me, so I held it very firmly against the railing of the bridge* and snapped the picture. Because I had the shutter open for so long (2 and 4 seconds) and because the traffic on the bridge was moving at a normal rate, the light trails remained, even after the cars themselves had moved on.
If you have a camera where you can control how long the shutter remains open, I encourage you to play around with it. There are lots of fun things you can do with the shutter speed.
Have you done anything creative with shutter speeds? If so, let me know and post a link to it in the comments.
In the meantime, as always, comments, critiques and criticisms about the pictures I posted are always welcomed and appreciated.
* Having a tripod wouldn't have helped so much anyway. One major problem that I have about taking pictures on the Brooklyn Bridge is that the *entire* bridge shakes!
On The Wings of Gerber Daisies
Sometimes, an Out-of-Focus Shot Works Well Too
The Ghosts Of Grand Central
Shooting From A Different Angle
Sunflower Arrangement (discussion of lens apertures and depth of field)
Empire (basic discussion of lenses)
Statue of Liberty
Trinity Church, September 11, 2008