Camera attachment (new build, planning stage)

[onre]

Hello,

New member here. The material I'm building a scanner for is mainly old (50-100 years) books with usually small-ish size and 500+ pages. I've already done some rudimentary testing with an X-shaped synth stand and cardboard to figure out how the process will "feel like", so to say, and to get source images so I got to play with Scan Tailor. As hardware, I have a mismatched pair of Canon cameras, one being an Ixus 50 and other an Ixus 80. I'm looking for another Ixus 80 because of better image quality and optics. SDM is installed on both cameras and I built a switch for a powered hub to handle the triggering.

So, looking at what people have done, it seems like the most popular approach is to make the cradle movable and platen fixed horizontally, so that when you proceed with the scan, the cradle is moved to accommodate lowering the platen to the new position of the "dividing line" between pages (what is the proper term for this - and did the description make any sense at all?)

I find it rather compelling solution to attach the cameras to the cradle itself with height adjustment. Given that the cradle angle is 90 degrees, the cameras would then "automatically" be in right angle compared to the page and platen. The only required adjustment would be the height relative to the cradle board, so that the camera cross-hair is at the center of the page. Has anyone done this or is there some good reason for abandoning this idea? Alternatively they could be mounted on the platen as well, but I'd somehow like it better if they were not raised and lowered all the time.

All comments are appreciated.

[onre]

So this is where I am now. Platen is a temporary hack. A proper mechanism for raising and lowering it is what I'm planning right now. Currently I'm thinking of using something like short pieces of wire in the mounting to make it freely movable when in lowered position.

[daniel_reetz]

I really like your camera adjusters - I don't think I've ever seen a design like that here. Very nice.

I don't know how I missed your first post. Generally, the issue with attaching the cameras to the platen is that they tend to vibrate when you set it down. However, that doesn't have to be the case. Your cameras are light and it looks like your build is pretty solid, so it may not matter at all. Also, if your lights are bright, your shutter speeds can be faster and the vibration has much less effect.

EDIT: Is the base of your scanner set up like a keyboard stand? I love the idea of folding it away...

[onre]

Thanks for the reply.

The camera adjusters seem to actually work quite well. I've used large washers so that when tightened, they force the piece of wood to correct position. They're mounted on the cradle through the large pieces of wood, so the hole is long enough to ensure that the threaded rod is at 90 degrees angle. The idea came to me while wandering around in the local hardware store and seeing the rods. That's one of the better parts of the build. I think I'm not going to move the cameras to the platen after all.

The base of this prototype unit is not like a keyboard stand, but it's definitely a viable option. I'm planning to make a small series of these to provide to other people of our hobby project, and those might very well be foldable to make them easier to transport and store.

Looks like I'll be getting non-reflecting glass (used in framing paintings) for next version of the platen. I've been pondering about the platen lift mechanism, and the current idea is something like a gallows with pulleys and wire to lower and raise it. I'll try to draw a picture of what I'm thinking, and how it would work. Optimally it would be controlled by pedal, so that pressing the pedal will raise the platen. Also, the gallows frame would serve as mounting point for lights. The supports for the gallows would only be on the back side of the scanner, so that the front is completely open to make page-turning and platen positioning easy.

edit: ...and yes, this one is rather solid. When doing woodwork, I seem to always do the same "mistake" of oversizing all load-bearing parts. I could've used way less wood and the end result would have weighed half of what it does now, probably. Well, at least it feels very solid and nice.

[daniel_reetz]

There are two kinds of glass - non-reflective and anti-reflection-coated. People here have had bad luck with the first kind - it's the kind that has a "blurry" or matte surface on one side.

[onre]

All right. The kind I'm getting is the "non-matte", so I hope it'll be all right. The pieces arrive this weekend so we'll see about it soon enough

[onre]

Got the matte glass. Works for text-only scanning, but is not good. The other camera arrived, too, so I went to local hardware store to buy miscellaneous bits and pieces to build a prototype platen lift. Here it is in place, the lift rope is suspended on a hook on the side of the frame to hold the platen up.

[onre]

Allright, the first prototype is now about ready. At least I'm supposed to scan a lot of books with it during next two days!

[daniel_reetz]

I'm very excited to hear about your experiences with the rope lift on the platen. This is a very innovative/adventurous approach, suggested many times but as far as I know, never implemented. Thanks for keeping us up to date!

[onre]

Hello and thanks for being interested in this.

After installing a proper wooden handle in the rope the lift has proven to be a great success. Our team spent twelve hours at an archive site digitizing material, of which time at least six hours was spent using the scanner. None of the operators felt that using it caused any sort of physical strain. Better-quality pulleys would make the platen raise in an even more balanced manner. Now the front edge rises maybe an inch higher than the rear, but this is not much of a problem. Overall it has worked very well. Next project is to build a smaller version for maximum B5 sized books and do small improvements on this one.