CMOS Sensor

• The D90 has a CMOS Sensor that is about half the size of the standard "full frame" in still photography. A full-frame sensor captures everything that the lens captures. The CMOS sensor crops out about half of what the lens see as information enters the camera.
  
  

Dust Reduction

• The Nikon D90 includes a dust-reduction feature that sends a small spurt of electricity to the sensor when you turn on the camera. The short current causes dust to spring off of the sensor.
  
  

Megapixels

• The D90's CMOS sensor records files with a maximum of 12.3 effective megapixels. The maximum print size at 300 pixel per inch is 14 inches by 9 inches.