Understand Noise in Digital Image
There is lots of confusion about image noise. The noise that is produced by image sensors when used at high ISO (amplified output).
Bottom line is, that nature sets the limits of the performance of sensors that use the same basic technology. And all current sensors do. Meaning, that they will all produce noise. Small differences can be established by using amplifying technology that produces little noise. And again all cameras do, some a little better than others.
So what makes that there are larger differences in noise performance between camera models? Well, one comes from the sensor/pixel size, because larger pixels capture more photons/light and need less amplification. A 12m pixel full frame sensor (like the D3) will produce less noise than a 12m pixel cropped (smaller) sensor (like the D300).
But the biggest difference comes from …….. noise reduction and not from the sensor or some wonderful new technology. This is nothing new and noise reduction was first widely used in digital compact cameras which use very tiny sensors. These cameras and their small sensors produced so much noise that noise reduction was necessary to get decent output even at lower ISO. No wonder that strong noise reduction is used in all modern compacts. Fuji was the first to introduce clever noise reduction in compacts that didn’t damage the image data too much.
For DSLR’s very little to no noise reduction was used in the earlier models. But when the megapixel race started and the pixel sizes began to shrink, it became necessary to use more noise reduction at higher ISO, but still very moderate compared to compacts.
So what has Nikon actually done with the D300 …. see full article.