What digital camera to use Specification in details to capture pictures business card size very clear?

Any camera will capture pictures "business card size" very clear. That is an extremely low resolution for pictures, and any camera can handle it. Unfortunately, a business card has different dimensions than a camera, so you're going to have to crop the picture to the size you need.

If you mean you want to actually take pictures of business cards, chances are you won't be able to - you'll have to take it off auto focus and focus yourself. Any auto focus camera will not be able to focus on anything that small that clearly.

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If that is the size you are interested in then any camera with no more than 2Mega Pixel will do you may go down to 1 Mega pixel. You do not need to spend the extra $$ for a camera with more than 2MP.

You want one that has a good macro capablity and allows for focusing very close in. The Nikon are good at this.