This month's Hands on mailbox was full of interesting questions, so I thought I'd take the opportunity to answer them in more depth in my column rather than on the Question time pages. So if you've ever wondered why Cmos sensors are beginning to replace CCDs in digital cameras, want to use your camcorder as a webcam or have just accidentally reformatted a memory card and want to get your pictures back, read on. Having read the review of the Canon EOS 300D in PCW March 2004, Saty Navalkar emailed to ask what the advantages of using a Cmos chip are compared to the CCD chips widely used by all other digital camera manufacturers. Essentially, CCD and Cmos image sensors do the same thing - convert light into an electrical charge - but they differ both in their internal architecture and imaging capabilities. CCDs were developed in the 1970s specifically for imaging applications. A CCD consists of an array of photosites arranged in a grid (in a flatbed scanner it's a linear array, which is passed over the document by means of a step motor).
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