This tutorial is a guide to help you make the most of some of those features.
• Understanding exposure
• Metering modes
• Exposure compensation
• Auto Exposure Lock (AEL)
• Flash options
When you take a photograph, a sensor inside your camera is exposed to light. There are three elements to this exposure – the brightness of the light, the length of time it is allowed to act on the sensor and the sensitivity of the sensor.
The lens aperture controls the brightness of the light. It opens or closes to let more, or less, light through to the sensor. The duration of the exposure is controlled by the length of time the shutter is open (the shutter speed).
The sensitivity of the sensor is controlled by the ISO setting. Whilst an ISO value of 100 has negligible amplification, the amplification at higher ISO settings makes it possible to obtain images in very low light.
This might make you think the best ISO setting is the highest one. But one of the effects of increasing the ISO is an increase in ‘noise’ – coloured specks that start to appear in the images. So, in very low light, exposure can be a compromise between detail and noise.
Many of the latest IXUS and PowerShot cameras feature the HS System. This combines the DIGIC 4 image processor with a high sensitivity CMOS sensor that lowers noise levels by up to 60% at all ISO speeds. This provides higher-quality images, even in low light.