Camera Shutter Speed
The camera shutter speed is the amount of time for which the shutter is open when you take a photo. A long shutter speed increases exposure, while a short one reduces exposure.
For this article, I'm going to assume a fixed aperture, so that short and fast shutter speeds and their effects can be compared directly. For the record, if you decrease the shutter speed, you have to increase the aperture size to maintain the same exposure.
Controlling camera shutter speed
Camera shutter speed is controlled by a wheel on the camera body (it feels serrated). The shutter speed can be set very precisely with this wheel, in increments of seconds and fractions of seconds.
For example, you could set the shutter to be open for 1/8th of a second, or 2 seconds. The range is usually quite large, from 1/1000th of a second to 30 seconds or "bulb" which lets you leave the shutter open for as long as you leave the shutter release depressed.
Photo Blurring
Quite a common problem with photography is getting blurred images. Blurring occurs when the camera moves while the shutter is open. To fix this, we can either make sure the camera doesn't move while the shutter is open, or we can set the shutter to be fast enough for any movement to have a negligible effect.
The appropriate shutter speed will depend on conditions, so play around. I suggest a tripod to remove all camera shake (inevitable motion of the camera which can result even from a light breeze) and you should hold your camera correctly.
Let me now move on to what happens with fast/slow shutter speeds. You can get some really interesting photographic effects with just this one variable.
Fast Shutter Speed
In this case the shutter is open for just a fraction of a second.
What do you think the resulting photo will look like?
I'm going to use a waterfall as my example. If I take a photo of a waterfall with a fast shutter speed, the result will be a "freeze frame" of the waterfall: I should be able to capture individual drops of water and the water will look stationary.
This is a waterfall in Holland Park, London, UK. This first image was taken with a shutter speed of 1/40th of a second.
As you can see the water looks a like a "freeze frame", but the effect would be a lot more pronounced with a much faster shutter speed.
Slow Shutter Speed
The next one was taken with a camera shutter speed of 2 seconds.
In this one, the water really looks like it was flowing and to me it looks "cleaner".
Just to remind you, the aperture sizes of these two were completely different - I used the shutter priority auto mode to take care of that for me as I wasn't in a position to adjust both easiy.
Show me some cool slow shutter photos!
OK.
This is my guitar. The light is a torch with the glass cap removed. This photo also demonstrates an effect called "depth of field". Notice that only a small region of the fretboard is in focus...
This digital photography technique is called "light painting".
OK fine, have another....
Wow, they must have been running really fast... or I left the shutter open for 2 seconds!
I hope this helps you to understand the basics of camera shutter speed!