Manual Techniques - ISO
ISO - International Standards Organisation
ISO enables to take images without using the flash and takes advantage of the natural light available in glommy conditions.
As the light gets dimmer the ISO needs to be adjusted.
ISO is set by M mode and selecting the set button which gives you the choice of ISO settings as shown below.
The higher the ISO the greater the risk of 'noise' which makes images look 'granier'.
ISO 100 - Bright daylight, sunny conditions, hand held shooting, where clean images (no noise are priority)
ISO 200 - As for ISO 100, but where a faster shutter speed or a slightly longer focal length is required and where you may also need flexibility with apertures and shutter speeds.
ISO 400 - Indoor or slightly overcast conditions, where you want to avoid using flash or you need fast shutter speeds and full aperture control to shoo hand held.
ISO 800 - Overcast or dark indoor shooting, sports or action photography, where you need to freeze the motion and noise issues are not a problem.
ISO 1250 - Low light or indoors, long lens shooting (hand held) at this level noise could become an issue.
ISO 1600 - Night time, low light, very long lens shooting. Noise will be evident in shots.
ISO 3200 - As for previous ISO but where high shutter speeds are required. Noise will be evident in shots.
Examples of different settings of ISO
ISO Setting: 200
ISO Setting: 1600