Project 52, Week 2

Exposure - Shutter Speed

Introduction

Last week we learned about the basics of exposure, how we need to get just the right amount of light into the camera to take a photograph that is neither under nor over exposed.  This week we will learn exactly what part shutter speed plays in this process.

The triangle of exposure

Your camera has 3 ways to restrict or increase the amount of light coming in through the lens:

1. Shutter speed

2. Aperture

3. ISO speed

Think of the light waves pouring in through the lens.  The shutter speed is the amount of time the digital sensor (or film) is exposed to that light.  The aperture is the size of the hole through which the light pours (large hole = more light).  The ISO speed is a measure of how sensitive the sensor or film is to the light (very sensitive = doesn't need as much light to reach correct exposure).  We'll cover aperture and ISO in the next couple of weeks - this week is all about shutter speed.

Shutter speed

For normal day to day photography, shutter speeds are measured in fractions of a second.  If left on 'P' or 'Auto' mode, your camera will probably select a shutter speed in the mid range of 1/60th to 1/200th of a second.  This is usually perfectly fine, but you should be aware of what it is doing and what the results will be.  For static photos you probably won't notice much difference if you use fast or slower shutter speeds, but if you take a picture of something that is moving, you might notice 'motion blur' appearing if you use shutter speeds of 1/60th of a second or slower (don't forget 1/200th second is faster than 1/60th second).

Compare this picture of a fast moving Ron playing Quidditch, taken at a very fast shutter speed of 1/800th of a second:

with this one taken at 1/60th of a second:

The photo at the very top of the article was also taken at 1/60th of a second, but it is pin sharp because Ron was stationary. 

What does this mean for me?

If you are taking a photo of anything moving (toddlers, racing cars, sports day, football match, wildlife), consider taking control of your shutter speed so that you don't getting a disappointingly blurred photo - the faster the thing is moving, the faster shutter speed you will need.  Your camera doesn't know that your subject is moving, and it won't know to dial in a faster shutter speed - it will stick to the mid range of speeds because that's what it's programmed to do.  All you need to do is move the dial to 'S' (or 'T' or 'Tv' on some cameras - stands for time value) and change the shutter speed to 1/200th, 1/400th or above.  (If you don't know how to change the shutter speed, look in the camera's manual.  Most manuals can be downloaded online if you've lost yours - look on the camera manufacturer's website.)

Just be aware that there are always trade offs in photography.  If you whizz your shutter speed up to 1/400th sec either your aperture or your ISO speed is going to have to compensate for the reduced amount of light coming in through the lens.  We will learn more about this next week when we look at aperture.  When you are taking your photos for this week's project, make sure you are outside in plenty of daylight and you shouldn't have any problems (if the camera can't get enough light in it may just refuse to take a photo, or it may take a badly underexposed one). 

This week's photo project

If you put your camera control onto 'S' it will let you dial in which shutter speed you want.  Try this now, and take the same photo using shutter speeds of anything from a whole second up to the fastest shutter speed your camera can manage.  Find something that moves and experiment with fast and slow shutter speeds.  If this is fairly basic stuff for you, try putting your camera on a tripod and taking some photos with very long shutter speeds. 

Have a go on the Canon website's interactive 'get off auto' website - you can try all this from the comfort of your armchair.

The aim of this week is for you to visualise what you want to do (deliberately freeze something that is moving, and also deliberately incorporate motion blur in a photo) and then make the camera do what you want it to by changing the shutter speed.  There will be plenty of trial and error, but keep checking your photos and you will learn from them.

Download your photos and file the ones you are pleased with and the ones you are disappointed with in different places so you keep a record of your progress. 

Next week:  Exposure - Aperture

Last week:  Exposure - Introduction