Hints: exposure

This section is about taking control of exposure. If you are happy to leave your camera set on automatic exposure and generally take 'average pictures' (whatever they are!), then you won't need to worry too much about this.

Auto mode is fine for many - or perhaps even most - shots. The problem with "AUTO" mode is that the camera makes its decisions based on fixed choices built into the camera's own operating system. These may or may not be how you want the camera to operate.

If you just want to know a bit more about the operation of your camera and make better pictures when things are not 'average', the following notes might help. Or they may help if you have picture problems. But do remember that these notes can only scratch the surface, and if you want to get into more detail there are many books that deal with the subject. Or come along to the Club and see if we can point you in the right direction (although our meetings do not always include formal tuition, there is usually someone who can help out).

Appropriate exposure for a given amount of light depends on three factors: the aperture, the shutter speed, and the film (or digital processor) 'speed'. Let's look briefly at each.


This is the adjustable hole within a camera's lens. The size is indicated by a number. The larger the hole, the smaller the number, eg, f2.8; the smaller the hole, the larger the number, eg, f8.0 or 16.

Related matters

Using a camera's 'aperture priority setting' allows you to set a chosen aperture and the camera will set the correct shutter speed (or will warn you if you have too much or too little light for the selected aperture setting).

Shutter speed

Shutter speed is how long the shutter is open, ie, the length of time the film [or digital image processor] is exposed to the scene being photographed.

Related matters

Using a camera's 'shutter speed priority' setting allows you to set whatever shutter speed you want and the camera will set the correct aperture [or will warn you if you have too much or too little light for the selected shutter speed setting.]

Film speed (or the digital processor equivalent)

In simple terms, this is the sensitivity of the film or digital equipment to light - how much light it needs to make a picture. It is usually represented by ISO numbers. Lower numbers are known as 'slow film' and higher numbers relate to 'faster film'. Slow film (lower numbers) need more light to create a picture. Fast films need less light to create a picture.