Tutorial - Shutter Speed
When taking a photo, your sensor is exposed to light so that it can record what it sees. The length of time your sensor is exposed to light is called the shutter speed.
Generally, most cameras can be set to have a shutter speed somewhere between 30 seconds and 1/4000th of a second, with professional dSLRs being able to go up to 1/8000th of a second.
Now, what is the difference in the picture when you use a 30 second shutter speed compared to a 1/4000th of a second shutter speed? Well, the longer your shutter speed, the more blur your photo will have.
If you are hand holding your camera and shooting with a longer shutter speed, the amount of blur due to unsteady hands will increase. This type of blur, due to hand movement, is usually not attractive. The entire image does not look sharp and can make someone feel dizzy. You want at least a portion of the image in focus, something for the viewer to anchor on.
Fast Shutter Speed
Slow Shutter Speed
Slow Shutter Speed
However, there are times when you want some blur in your image. Usually the type of blur you want is due to the subject moving. For example, when you take a picture of a waterfall, the longer your shutter speed, the more smokey and smooth the water looks. This can be an aesthetically pleasing scene. However, if you were to try and hand hold the camera, while getting the smokey water, you would not be able to hold the camera steady enough to get the rocks or surrounding area around the waterfall sharp. This is where a tripod comes in. A tripod will hold the camera steady so that only the water is moving while the rocks and surrounding environment is sharp as in the second picture above.
There are a couple of ways to slow down your shutter speed. However, without changing your aperture or ISO, the easiest way is to use a filter. We will discuss how to change the required shutter speed using aperture and ISO in the 4th part of the Basic Photography tutorial.
Filters are pieces of glass that generally go in front of the lens to alter the light. There is a huge selection of filters, however the three most common ones for digital photography are a UV filter, (basically just a clear filter used to protect the front element of the lens from scratches) a circular polarizing filter, (used to minimize glare and reflections, and saturate blues and reds) and neutral density filters. The ones that affect the amount of light and therefore your shutter speed are neutral density filters and, to a lesser extent, circular polarizers.
We are mainly concerned about the neutral density filters right now. They are dark filters, intended to not change the light in anyway other than letting less light hit the sensor. When taking photos in daylight, the amount of light can force you to have a fast shutter speed, for example, in the waterfall photo above. By using the neutral density filter the photographer was able to limit the amount of light hitting the sensor and lengthen the shutter speed to blur the water.
Fast Shutter Speed
There are times when you want to freeze the action. For example, a bird in flight or as someone scores a point in sport. To do this, you need a faster shutter speed. This means there is less movement while the shutter is open and the image will be sharper.
Without changing any other settings, when you speed up your shutter speed, less light hits the sensor. This means that your image gets darker. To fix this, you will have to add light to the scene. Depending on where you are, and what you are shooting, there are a few ways to fix this. If you are indoors, you could open curtains, turn on lights or possibly go outside. if you are already outside, then you will probably have to either add light in the form of flashes, or change some of your settings. We will go over the settings you could use in Part 4 of the Basic Photography Tutorials where we will talk about how Aperture, Shutter Speed and ISO all fit together. Right now, however, we will talk about flashes.
There are two different ways to light a photograph. There are flashes or there is continuous lighting. Continuous lighting is used more in video production or baby photography (as it's not wise to use strong flashes). In this tutorial we will be speaking about flash photography as it can have an effect on your shutter speed.
One thing about flash photography is that even in the manuals, people talk about the power setting. The higher the power setting, the brighter your photo will be. That concept makes sense. However, when you lower the power of a flash, the brightness of the flash stays the same. What changes is actually the duration of the flash. When you "lower the power" on a flash, the duration of the flash actually shortens. Some flashes, depending on the model, can fire at 1/50 000th of a second.
If you are taking photos of humming birds, even shooting with a shutter speed of 1/8000th of a second is not fast enough to freeze the wing movements. To do this, a photographer will usually set up three or four flashes around the area where a humming bird frequents. With the flashes set at their lowest power, the duration is usually fast enough to freeze the wing beats as well as provide enough light to overpower the ambient light. Since flash overpowers the ambient light, the blur from the wing does not show up in the final picture.