How to capture light with a digital camera
The camera’s image sensor is what captures light when the shutter opens. There are two primary types of sensors used in digital cameras today: one is called a CCD (Charge Coupled Device) and the other is called CMOS (Complimentary Metal Oxide Semiconductor).
How does a CCD or CMOS work?
The camera’s image sensor is the equivalent of the film that you would buy for your regular camera. A photograph is captured on film when the film is exposed to light.
A digital image sensor converts light into electrical signals, which are then converted into an image inside of the camera using the camera’s image processor.
I have seen beautiful images produced by Olympus, Nikon, Canon and Sony cameras. I have compared them side by side. I have enlarged them by 300%. With my discriminating eye, can I tell the difference between a CCD or CMOS sensor? Not really.
Dust and the SLR sensor
Dust is the bane of most electronics equipment, especially computers. The good news for most digital camera buyers is that their cameras are completely sealed, so that dust can never get inside.
If you are considering a digital camera with interchangeable lenses (a digital SLR) then dust can be a problem. If a particle of dust happens to land on the image sensor when you are changing lenses, this tiny particle will show up as a large spot in your digital photographs.
Many of the more modern digital SLR cameras have sophisticated ways of cleaning the sensor, and have mechanisms that prevent dust from landing on the sensor.
Also, the dust problem is pretty rare if you are careful. The main point here: when you change the lenses on your digital SLR, try to do it in a fairly clean environment. Once a particle of dust gets on the sensor, it is a real pain to get it off.
The Basic Rule of Thumb
Arguments abound about why CCD and CMOS sensors differ from each other, but this should not sway your decision-making when you’re comparing different cameras. Look for other features first, then find out what type of sensor the camera has.