Digital Noise
Nikon DSLR's are well known for their noise-reduction capabilities. The ability to reduce noise is not the same for every Nikon DSLR, however. The components that go into making camera bodies vary and can have a significant impact on the amount of noise that will be present in the images it captures. It's what's inside that counts.
Noise
Noise is the appearance of random flecks of color in a digital photo where there should be nice smooth colors. If you've ever seen a photo that looks grainy or appears to be a bit snowy, you may be looking at an example of noise in a digital photo. Sometimes we might say a photo looks fuzzy when we see one with a lot of noise.
Causes
A digital camera's sensor collects photographs as light. That light and the subject of your photo need to then be converted into an image. This happens electronically inside the camera. That process can cause some of the pixels to interfere with their neighboring pixels electronically. The result is pixels that contain random colors. This is amplified at higher ISO's because the camera needs to use more of a charge to convert the light to an image. The higher the ISO, the more noise will be introduced into an image.
Noise Reduction
There are two main components that help keep noise to a minimum. The size of the image sensor is the biggest. A bigger sensor spreads out the pixels, reducing the amount of electrical interference between them when they go through their conversion of light to image. The other is software built into the computer that recognizes noise. The software alters the color and smooths out the area reducing the visible appearance of noise.
D300s and D700
The two bodies have a similar number of mega-pixels. The D300s has 12.3 MP while the D700 has 12.1 MP. The big difference is the D700 has a full-frame sensor that is larger than the D300s' APS-C sensor. Spreading out the same number of pixels across a larger area will usually result in less noise and in this case it does. The amount of noise present in an image from the D700 at ISO 320 is roughly the same as the amount of noise present in an image from the D300s at ISO 125. The measured difference is about 1.5 stops of ISO between the two bodies across the ISO range from 100 to 6400. The D700 will consistently deliver photos with less noise than the D300s at equal ISOs.
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