Gregory Maxwell wrote:
For digitizing what?
Exactly, that's the first question.
Archive.org digitizes books using a pair of canon 1Ds (? perhaps it was a 5D? In any case the 5DII would be sufficient now) on a custom stand with a hacked up copy of gphoto2 to actuate the cameras.
That's Brewster Kahle doing things many years ago (2002? 2003?). Today, a much cheaper low-end digital SLR, or even compact cameras will give you the needed 10 or so megapixels. But again, if you need to pay your staff, a ten times more expensive camera might easily pay its own cost in increased speed, or increased shutter lifespan.
I'm not sure how they're dealing with curvature (I think they just may lay a glass plate on the pages), but it would be easy enough to solve using a laser pointer with a pattern generating holographic grating and a second exposure to capture the page distortion and some fairly simple software processing after the fact.
The Internet Archive apparently uses a fixed glass, and lowers the book cradle to turn pages, http://aipengineering.com/scribe/
Other designs have a fixed book cradle and lifts the glass, e.g. the Atiz DIY, http://diy.atiz.com/
I thought the Internet Archive design was very clever, since it keeps a fixed distance from lens to book surface (beneath the glass), until I saw the bkrpr.org where you just lift everything. That's a design for 2009! I haven't tried to build one myself yet.
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However, you can capture lots of books (that can be opened fully) with a single camera, laying the book flat on a table with a glass on top. That's just like a flatbed scanner (but much faster) turned upside down.
In January 2008, I used a 10 megapixel Canon EOS 400D (Digital Rebel XTi) with a 50 mm lens to shoot this, laying flat on a table under a glass, http://runeberg.org/stridfin/0226.html
On that webpage, the image is reduced to 120 dpi (1.2 megapixel), but the original is 300 dpi (7.5 megapixel). The map shown is reused in http://en.wikipedia.org/wiki/Battle_of_Alavus
That's an example of how one specialized book can be very useful for a limited Wikiproject. This book was published in 1909 for the 100th anniversary of the Finnish War (1808-1809), and digitized in 2008 for the 200th anniversary.