Image Sensor

In the old days, cameras had films that captured all the light let in by the shutter. When you had a regular camera, if you wanted to take special pictures you would buy the "more expensive film". Digital cameras don't use film obviously, but the counterpart is known as the image sensor. The reason it is important is because you can't buy a new image sensor if you wanted "special" pictures.

There are currently two different kinds of image sensors, CCD and CMOS. The former is the technology used for the past two decades and it is fine. The advantage of CMOS is for the manufacturer in that they are cheaper to make. At present, there is no need to base your decision on a consumer digital camera on which type of image sensor is used. However, professional digital cameras such as the Canon EOS D60 use CMOS image sensors. This is likely to become the standard of higher-end cameras.

However, the size of the image sensor is important. As usual, size does matter. If two cameras have the same megapixel count, the one with the larger sensor will produce better quality pictures. The reasons for the difference are related to mathematics and how the light is processed, so we will not go into that, but if you're interested read this article at www.photo.net.

Image sensor size is probably a more important determining factor of the price of a digital camera than the pixel count. But this is where a compromise must be made. Many people are looking for a small camera that can fit in a pocket, so it can't be expected that ultra-compact cameras will have large sensors. There's not enough room.

Aside from the size of the image sensor, the sensitivity of an image sensor also dictates part of the price. If you remember purchasing film, you are familiar with ISO 100, 200, or 400. The higher the ISO number, the more sensitive the film and the less light it needed to take the picture. There are other advantages to using high ISO film, including not needing flash in dim light and better freezing of moving objects.

In the same way, digital camera image sensors have ISO ratings. Just about every digital camera will have settings with a sensitivity equivalent to ISO 100 film and ISO 200 film. Many will have an ISO 400 setting, but above that the images from cameras with small sensors gets pretty noisy. The more expensive digital SLRs with much larger sensors have much higher sensitivity settings. At ISO 400 they are virtually noise free and some can go as high as ISO 3200 or even ISO 6400!

It is sad that most retailers advertise digital cameras by only listing their resolution. It becomes up to the consumer to figure our why one 4MP camera is $250 and another 4MP camera is $600. Now you know one of the main reasons. Next we will discuss the other reason, the zoom capability.