Zooooooooooooooooooooooom! A car flies by and you take a quick picture of it. Your camera freezes that moment in time and you have a picture of car that is seemingly going no where. It's flat, nothing seems to be happening in your image. How could you improve this? One answer could be taking full control of your shutter speed.
Shutter speed is the length of time that your camera's shutter stays open allowing light in to hit the sensor. The longer your shutter stays open, the more light you are allowing in. Conversely, the faster your shutter speed, the less light you allow in. Remember this fits into the exposure triangle and needs to be balanced with aperture and ISO as well. Shutter speed is most often expressed in fractions of a second such as 1/200 or 1/4 but can also be expressed in seconds like 1" or 30". One thing to keep in mind is the longer you keep you shutter open, the more stable you need to be to account for body movement (or else use a tripod). If you are not stable this will result in a blurry image that appears out of focus. Depending on what type of photography you are doing (or what you are trying to convey) will depend on what is the proper shutter speed to use.
Let's say you are shooting your kid's sports match. Whats the best way to approach this? You need a shutter speed that is fast enough to freeze time but also slow enough to let enough light in for a proper exposure. Personally I try not to go under 1/200 when I am shooting anything in motion and even that can be considered "too slow." For sports even quicker may be needed at around 1/500. Another important piece of info to note is what focal length you are shooting at will effect what is the slowest shutter speed you can use. In photos taken with a wide angle or wider angle focal length, details are less important therefore you can get away with using a slower shutter speed. However if you are using a zoom lens details are more important and this will cause you to need to use a much faster shutter speed.
Note that when shooting images handheld you should never go below 1/focal length with your shutter speed. For example if I am shooting at 200mm I should never be shooting anything slower than 1/200 of a second (please account for crop on focal length which I will explain in a following article).
However lets say you're not shooting sports and you want to convey a different message, maybe some motion blur in a car in a city shot to show how busy the city is. How do you achieve this? Slow down your shutter speed. Personally when I am trying to convey motion blur I aim in the 1/10 to 1" range when its comes to shooting waterfalls or car blur. In waterfalls it gives you that creamy look while still holding texture. For cars it allows you to really stretch the length and convey motion. Now if you slow down your shutter speed, this needs to balance, since you're allowing more light in you would need to make your aperture hole smaller (a bigger f number). Motion blur shots during the day are hard since you will end up overexposing most of the time. You can manipulate the amount of light your camera uses by using what are called filters which we will discuss another time.
Night time landscape photos in order to be sharp will need to be taken on tripods with a long exposure of somewhere between 5" - 30" in order to allow enough light in. I will write a post on night photography in the near future.
Below are some images that I will list settings of to help you understand how shutter speed can be conveyed.
I hope these examples at least helped you understand how shutter speed functions. If there is any confusion feel free to leave a comment below so I can address anything I missed. Again remember to use a tripod for anything slower than 1/focal length of your lens!
Stay true to you.