If you've been shooting with digital cameras for any length of time, you probably have heard the phrase "noise." But what is photography noise? And what effect does it have on your pictures?
What Is Noise?
Simply put, noise shows up on images as unwanted color specks. These will often be of a different color to the image. For instance, pink specks could show up in green grass. Often, noise looks like grain on an image.
What Causes Noise?
Noise can be caused by excessive heat. This is known as "thermal noise." More commonly though, noise is caused by increasing the ISO on a DSLR camera.
As you increase ISO, you gain more light into your image. As with any electrical system, however, this gain introduces noise into the system. And, because the light levels are weaker, signals are amplified and the noise is amplified in conjunction.
Why Are Some DSLRs Better at Dealing With Noise?
To understand how DSLRs deal with noise, you need to understand digital sensors.
Digital cameras -- whether compact or DSLRs -- are equipped with a CCD or CMOS image sensor. These sensors are made up of pixels, which can be thought of as light sensors which convert light into an electric charge. These charges send analog signals to an A/D converter, which converts them into digital pixels.
The size of these image sensors, or chips, affects the amount of noise that a camera produces. A smaller chip means that the effective size of the pixels is smaller, and this leads to more noise.
Therefore, the larger size of each pixel that a camera has, the less noise it will produce. But, in conjunction with this, a crop frame or APS-C camera is likely to produce more noise than a full frame camera as, again, the sensor will be smaller.
However, it should be noted that digital technology is improving all the time, and new technologies are appearing that may reduce the problem of noise even further.