CCD and CMOS sensors explained

5 04 2011

If you have shopped for a digital camera recently you may have noticed on the specs sheet that the camera has either a CCD or CMOS sensor. Which stands for the the kind of sensor that your camera is using to convert light into a digital image.

Sensors work just like film. In the old days, light entered the camera and struck the film. The light corresponded with chemicals on the film; which released dyes and created a color photo. In the digital age, film has been replaced with digital sensors. Which both do the same thing, make a digital image, but in a different way.

Both sensors start by converting the light from the image into electrons. Next is where they deviate to their own methods.

CCD sensors take that electron charge and transport it across the sensor’s surface where it is then read at a corner. Where an analog to digital reader then takes each pixel and assigns a digital value to it. CMOS sensors have transistors at each pixel that boost and transport the electron charge using wires, according to Howstuffworks.

Due to differences between the two sensors, the end product is different. According to Howstuffworks, imaging devices with a CCD sensor produce higher quality images, especially under low light. Due to how the light is moved across the sensor itself. CMOS sensors, tend to produce noisier images lowering their image quality. They also have a lower sensitivity because of the light hitting the sensor may hit the transistor and not the photo diode, according to Howstuffworks.

I used to own a Nikon D60, which uses a CCD sensor, and I’m currently using a Nikon D90, which uses a CMOS sensor. Although CCD images are supposed to be less noisy images shot under low lights with my D60 were more noisy than my D90 pictures. Even then, both Nikon’s and Canon’s professional cameras, D3x from Nikon and the 1D Mk.2 from Canon, both use CMOS sensors. So, I feel that saying CMOS sensors produce images of lower quality than CCD sensors is incorrect.