Definition: Image Sensor

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Image Sensors are the nitty gritty end of the digital camera. Basically the digital version of film. But just as there are lots of different types of film that you can buy, there are also lots of different types (or sizes) of image sensors, and this can be important when choosing a digital camera.

What is an Image Sensor:

An Image Sensor is a device that converts an optical image to an electric signal. It is used mostly in digital cameras and other imaging devices. It is a set of charge-coupled devices (CCD) or CMOS sensors such as active-pixel sensors. (from Wiki)

Why is the Image Sensor important?

Image sensors come in different sizes, and which size you have will affect the image quality of the photographs taken with it. Full frame sensors are the same size as 35mm film, but they are part of very expensive professional DSLR camera’s!

As always lets look at the simple description:

Compact digital cameras generally have a 1/2.5″ sensor (3% of full frame sensor)

Common DSLR digital cameras generally have an APS-C sensor (around 40% of full frame sensor)

Whats the difference?

So DSLR’s have much larger sensors than those in compact digital camera’s, therefore they have greater image quality.

Some digital compact cameras can be 10 megapixel’s, the same as some DSLR’s (or more) so how come they aren’t as good when it come to image quality?

This is where the size of the image sensor comes in. Take two 10 megapixel camera’s - one compact and one DSLR. The manufacturer is trying to fit the same amount of pixels on the smaller compact sensor as they are on the much larger DSLR sensor. And this is the important part, the compact’s pixels have to be smaller to fit on the sensor, and therefore it reduces the amount of sensitivity and light that the pixels can capture and that works out as a loss in image quality.

Obviously this only comes into the buying equation when you are concerned about image quality, which is another reason why I am looking at a DSLR as my next camera.

Image quality becomes a big factor when you want to print images or enlarge them, anything much larger than 6 x 4 or maybe 7 x 5 and you will notice the difference between the compact and the DSLR.

Mandy

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