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Do Digital Cameras Need Shutters?

Turns out, there's no need for a shutter. iStockphoto.com hide caption

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iStockphoto.com

Technology can be confounding. For the most part, we understand it only on the peripheries.

The rare exception seems to be photography. In high school, plenty of students learn the basics of a film camera. That's what I did, so as I shopped for a new digital camera, it suddenly dawned on me: I understand the relationship between film, exposure and a shutter but why does a digital camera need a shutter?

I took the question to David D. Busch, the author of a ton of books on photography, among them Digital SLR Cameras & Photography For Dummies. In essence, he said, digital cameras don't need a shutter. It's just easier and better if they have them.

"Many point-and-shoot cameras ... actually have no physical shutter, which is why they have a 'shutter click' noise you can turn on and off," he said via e-mail.

After The Jump: Busch Gives A More Detailed Explanation.

But there are drawbacks to this, he said. The extra electronics needed in shutter-less cameras usually mean a smaller chip, which "reduces the amount of area that can be used to capture light. Such sensors typically have more noise ('grain') in the images, and are less sensitive to light."

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And more importantly, perhaps, he adds, in a camera with a shutter "any residual charge on the sensor remaining just before the picture is taken is 'dumped,' leaving a clean sensor ready to capture an image. The closed mechanical shutter is then opened to admit light, and closed again after the exposure is finished. The charge on the sensor at the instant the shutter is closed is transferred off the chip and stored as an image."

We know you have these kinds of questions floating around in your head. Send them to us. We'll find answers.