DIY Book Scanner

The Cannon A2300 are on sale this week, and has a 5x lens and a few more pixels than the A2200, but lacks manual focus.

http://www.usa.canon.com/cusa/support/c ... shot_a2300

Those that have the 2200 does the autofocus usually work or do you find yourself needing to go to manual?

I would not choose a camera which didn't support manual focus. Most books have pages with lots of white space at the beginnings and ends of chapters (and elsewhere). Most autofocus cameras depend on contrast in the center of the image to work properly, and fail on these pages which don't have text in the part of the image the camera attempts to focus. The default seems to be "focus at infinity" which is never what you want in a bookscanner.

People have tried various workarounds (e.g., shoving a page into the image for the focus, then withdrawing it for the shot), but I think the better option is to begin with a camera that supports manual focus.

ETA: Actually, though I said "manual focus", what I really use is "autofocus lock". The number of cameras which support this option is larger than the number which support true manual focus. I had not realized previously, for instance, that my shirtpocket Powershot SD1200IS has autofocus lock support (half-depress shutter to autofocus, and press the normal/macro/infinity button to lock the focus). Since it also has higher resolution than the cameras I'm currently using for my scanning, I'll probably be shooting some tests with it soon.

daniel_reetz wrote:If any of those models support CHDK, then that's the one to buy.

I have seen "CHDK" mentioned a lot on this forum. What are the main advantages of using it that make it so crucial? For example why would a 16 MP Canon with "CHDK" be superior to one of the new but comparatively priced 20 MP Nikon Coolpix?

CHDK exposes features of the camera that might not otherwise be available with the camera's stock firmware. I'd say the main feature provided by CHDK used in book scanning is the ability to trigger the camera's shutter remotely from a push button located near your hand.

dpc wrote:CHDK exposes features of the camera that might not otherwise be available with the camera's stock firmware. I'd say the main feature provided by CHDK used in book scanning is the ability to trigger the camera's shutter remotely from a push button located near your hand.

I spoke over the phone to a Nikon technician at their showroom here in Bangalore and he said that they are aware that there is a market for students who want to use their cameras as an alternative to Xerox machines and they are taking notice. He said that their cameras have Blue Tooth /wireless connectivity and can be fired using your mobile phone or other device and you could even fire more than one camera at same time. He invited me down to the showroom to demonstrate a workflow for capturing images from a book. I will go after the holidays and if it is inspiring give a report. If what he says is true then a 20 MP Nikon at same price as a 16 MP Canon is a no brainer. 25% more pixels.

I still think you should strongly consider going the Canon/CHDK route, as the features you get blow pretty much everything else at that price point out of the water:

• Apply all kinds of settings, exposure, sensor sensitivity, manual focus, shutter speed, etc, stuff you usually only get with higher-end cameras
• Do full remote capturing from your computer: Trigger capture -> directly store on your machine without going through an extra "download from SD-Card" step
• You can script literally everything about your camera, thanks to the built-in Lua interpreter
• Shoot in RAW/DNG

From what I could gather, the Nikon wireless triggering is based on a very limited RESTful protocol that doesn't go beyond "trigger shot, download image".
Plus, the community is rather active and super helpful!

I already have 2 Canons so I will try CHDK, but for me it was not so much the price point but the higher resolution 20 MP compared to 16 MP which give you much better images to start with. Will still go to the Nikon showroom to see what they have to offer.

jbaiter wrote: [*]Shoot in RAW/DNG

What are the advantages of RAW for someone who uses Adobe "clear scan" as the last step?

I think in that case you don't really need it
RAW is nice because you have a lot more control about how your images are processed, as it's basically a 'raw' dump of the data the camera's sensor outputs.
I haven't used it myself extensively, but I think it's a 'nice to have' when you want to be able to do some more customization.

Shyamasundara wrote:I already have 2 Canons so I will try CHDK, but for me it was not so much the price point but the higher resolution 20 MP compared to 16 MP which give you much better images to start with. Will still go to the Nikon showroom to see what they have to offer.

Unless you are scanning newspapers or something similarly large I would question the value of a 20 MP camera for this application. A standard-sized book can be more than adequately captured with an 8 MP or 10 MP camera. Beyond that, you're increasing your processing time and storage requirements without significantly increasing the quality of the final product. Even small type (superscripts in footnotes, for instance) can be easily resolved in a 12 MP image.

Of course, if you're also planning to use the cameras for general photography, there may be a good case for 20 MP.

I use CHDK to create a custom grid for framing the books, and a timer script with audible cues for shooting. As jbaiter has mentioned, CHDK can also be used to preview the images on a computer, shoot, and download the images to the correct folders on the computer as they're captured and dozens of other things nobody's even thought of yet.

I would not recommend RAW images for this application; they explode your storage requirements, and would only be justified (IMO) if you're doing something like archiving artwork for the Metropolitan Museum.