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December 30, 2008 - Dave Hecei
Anyone who has shot film probably knows about ISO, or film speed. This number – 64, 100, 200, 400, 800, etc. – is a representation of how sensitive the film is to light. The higher the number, the more sensitive it is to light. If you wanted to shoot in lower light, use a higher ISO film. For situations where you have lots of bright light, then you can use a lower ISO speed. There is a trade off in the different speeds. Lower ISO films are more colorful and have tight film grain for sharper photos. To get higher ISO speeds, the film has to have larger film grains so images can look ‘grainy’. In choosing an ISO you need to compromise the speed with the amount of grain and sharpness.
Enter the digital camera that has no film. Digital camera sensors act as the film, and just like film can operate at different light sensitivities. Just like film cameras, digital cameras have ISO settings. The great thing about digital is that you can change the ISO at any time, unlike film where you were pretty much stuck at one speed throughout a roll of film. On a digital camera, the ISO actually acts to boost the sensitivity of the image sensor. When shooting at higher ISO settings, the electronic enhancing of the image usually causes noise in the image. This noise is very similar to grain in high ISO film. The higher the ISO setting, the more noise you will get.
Newer DSLR cameras have hit the market with better sensors, but they also have better processors inside. These chips can perform amazing things to the digital image, helping to reduce or eliminate much of the noise induced by boosting the sensitivity of the sensor. The first cameras to do this were of course the professional models, like the Nikon D3. As with most technology, it does eventually trickle down to the consumer lines.
For those who don’t want to, or can’t afford to, upgrade their camera body, there are some nice software solutions for removing noise. Two amazing packages are Noise Ninja, from Picture Code (www.picturecode.com), and Neat Image (www.neatimage.com). They both have home and pro level versions, prices vary.
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