Non-binding-breaking Book scanners (Was: Looking for PDP handbook
cisin at xenosoft.com
Fri Feb 19 13:21:16 CST 2016
>> http://www.diybookscanner.org/ :)
> Ooh, that's pretty cool.
Yes, but, . . .
I've participated in building a few similar devices.
Instead of the two sides MEETING in a V, there should be an open area
right at the spine to accomodate the greater thickness of the spine
itself. Having the two side panels able to slide up and down, with pegs,
a few inches would accomodate that and permit a varying amount of spine
Lighting. Ideally, lighting for copy work should be at a 45 degree
(1/4PI) angle. That way specular reflection (glare) from glass cover
(still needed occasionally!) or even just glossy paper, is not going
towards the camera. If the trough faces north/south, then that can be
done with light(s) north and south of the unit. Using two lights makes it
much easier to get acceptably even illumination. Some people prefer
various forms of diffuse light, or coaxial lighting ("ring" light).
Having the camera at a fixed position relative to the work holder is great
IFF you are doing consistent size. Different sizes could be dealt with
through variable focal length ("zoom") lenses, but that is not always the
ideal solution. I like to use FLAT-FIELD lenses, which are generally
fixed focal length (sometimes called "primary lenses"). Enlarger lenses
are an extremely cheap source for those. Being able to move the
camera/work distance closer/farther requires a movable mount to change
distance, but keep the camera centered relative to the work. North/south
motion can be easily handled by moving the book along the trough,
preferably with a fence, or simple bench-dog stops. The other motion
generally requires the camera mount to be a pole at a 45 degree (1/4PI
radians) angle relative to the work. Since the work is at a 45 degree
angle from vertical, that means that the pole can be VERTICAL, with the
camera mount aimed at a 45 degree angle. The post should be offset
slightly from the north/south center, with the movable camera mounts
holding the cameras at 45 degree angle (preferably with the focal node
close to that central plane).
Positioning of the book would require placing it so that it is centered
north/south (calibration marks, as well as fence or bench-dogs, are very
helpful!) and moving the camera up and down and focussing for distance.
NOTE: use of other than 90 degree (1/2 PI radians) for the book holder
would require further changes!
Grumpy Ol' Fred cisin at xenosoft.com
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