Camera Clinic: - occasional hints and tips to develop technique
Generally a camera will meter (sample) light from across the whole frame, then give you a sort of average exposure.
This can mean that highlights are over exposed or shadows under exposed (or both). There are various ways to overcome or minimise this BUT for now, lets just look at using spot metering.
In spot metering mode the camera takes a measurement from a single point or spot. This area is often at the centre of the frame, but it may be linked to the active (focus) AF point.
Where is it?
You will need to find out if your camera has a fixed spot – or if can you move it, BUT you do need to know where it is - generally represented by a small circle (spot) in your viewfinder.
To activate the spot meter if you have one, you will either
find a button/dial on the camera
or, have to select it via your camera's menu
How to Use It
You can use spot metering in conjunction with Auto Exposure Lock
The auto exposure lock (AE-L) function on a DSLR camera lets you physically lock the exposure reading from anywhere in the scene – i.e. where you place you SPOT METER point.
So, place your SPOT over the part of the frame where you want the meter to read the correct exposure. Then, depending on your system, you can:
use the AE or AEL (same thing - might even be an asterisk/star) button to lock in that exposure – reframe the shot and take
Or, you may be able to half press the shutter – to get the focus and metering locked – then hold it, reframe and shoot.
Most DSLR cameras have an auto exposure lock button – try to get to know your camera.
Some cameras will let you fix focus point and exposure (spot) together so that you can frame your shot first (for example on a tripod) – then move your focus and exposure point in the viewfinder.