Noise in a digital image is the same as grain in a film image. Noise looks like random speckles where it should be smooth. While there are times this look enhances an image, generally we avoid noise (kind of like banana flavoring – once in a while okay, but usually pretty distasteful).
To not have noise, you need to stay away from the things that cause it!
Noisy Things:
- High ISO – Keep your ISO as low as you can for a smoother look.
- Underexposed photos lightened in post-processing – Noise is most prevalent in shadows. When you lighten an underexposed photo, the noise in the shadows will increase.
- Long Exposures –When your shutter is open for seconds rather than fractions of a second (like for a night shot), you’re going to start seeing noise. To help this, both Canon and Nikon dSLRs have a Long Exposure Noise Reduction feature. See your user’s guide for how to turn it on.
Other Tips for Less Noise:
- Use a higher-end camera. For example, a Canon 1D will have barely, if any, noise when shooting at higher ISOs. Comparatively, when using the same ISO with a Canon Rebel, it could ruin the image.
- Purchase a noise-reduction plug-in such as Noise Ninja, Noiseware, or Dfine. As a bonus, these smooth skin as they reduce noise. Lightroom 3 also supposedly has a great noise-reduction feature, but I have not yet upgraded to test it.
- Put your camera on a tripod. If you don’t have a moving subject, this will make it possible for you to lower your shutter speed instead of raising your ISO.
Something else to know about noise:
Images usually look noisier on a computer screen than they do printed.
My rule of thumb is to avoid as much noise as possible, but I’d much rather get the shot than not – even if that means having noise in my image.
Source : http://www.spectrumphotographytips.com
