DIY Book Scanner

reggilbert wrote:The answering forum member also seemed to think it was worthwhile to invest in higher-speed cards, though he does not mention what kind of photography would show a benefit. It could be worth experimenting with card speed under the conditions the camera will be used in Haiti, since even a short delay in the camera processing speed, beyond the time it takes the operator to turn a page, could considerably length an operation with so many thousands of pages to scan.

Judging from his other posts, Brian is probably talking about action shots. If that's the case, he probably aims to use the camera's burst mode to take more than one shot per second, which requires very fast writing to the SD card to avoid filling the camera's buffer. That isn't going to be necessary for book scanning, where the physical work of lifting the platen and turning pages means that it's not possible to take photos that quickly, anyway.

I also found the comments about the dynamic range and highlight performance at ISO100 vs 200 interesting. I wasn't aware of that. I'm going to have to do a bit of experimenting to determine which is going to be the more appropriate setting for book scanning.

After a bit more research, it does look like ISO200 is the real base ISO, and ISO100 is achieved by software processing. Most cameras hide their "fake" ISOs from raw mode, but it seems the E-P1/P2 don't. In that case, I'd recommend using ISO200 on this camera for archival imaging - not 100. Sorry about the misunderstanding, Donna!

Thanks, folks, for the helpful input about high-capacity (but regular write-speed) SD cards and use of ISO200. We'll use both of those suggestions.

We encountered a challenge with the drawer slides. When used horizontally, for drawers, gravity doesn't come into play. But when used vertically, as with our book scanner application, the ball bearing cage may be drawn down by gravity. This is the case with a two-segment drawer slide that we started out using. We noticed that our range of vertical motion decreased and decreased until it was less than 2 inches high. It turns out that, with repeated motion, the ball bearing cage settled down low on the slide and would no longer go up any higher.

Following Daniel's helpful input yesterday, today I went to Home Depot and bought drawer slides that have three segments. The middle segment frames the range of motion of the bearing cage. We'll try these out today. The product is called 18-inch (450 mm) Full Extension Drawer Slide. The part number is D80618C-ZP-W, and the UPC is 8-85785-31314-5.

Thanks,
DonnaA

DonnaA wrote:Thanks, folks, for the helpful input about high-capacity (but regular write-speed) SD cards

I'd like to repeat my suggestion that tests be conducted on card write speed unless it is trivial to get replacement high-speed cards in Haiti if needed. It makes sense that this would seem to be a non-issue - it seems that none of the scanners who have posted on this forum for the last couple years has mentioned card speed or camera write delay as a problem. But I wonder if there is a difference between scanning a few dozen 300-page books that output to the minimum quality demanded by Scan Tailor and scanning 80,000 larger pages to presumably higher standards (given the daunting transfer to database that is envisioned). The particular combination of camera hardware, camera software, and card speed might in fact cause a delay that is longer than the platen-raising / page-turning interval. If I were to guess, a regular speed card will work fine, but just on the off chance that it wouldn't, it is easy enough to do a thirty-image check with the camera's included card or borrow a regular speed card, just to make sure, and if there turns out to be a delay to borrow a high-speed card from someone to see if it makes a difference. And the cost difference of $15-$25 is not so great if high speed turns out to be even marginally useful.

That's a good point, reggilbert, and I will do that experiment. I want to verify that the large capacity cards work ok, so I'll check for the write-speed tolerances in our usage scenario too. We do want to send the initial configuration with everything that is needed.

Thanks,
DonnaA

Look, write speeds will not be an issue. I was firing the EP-1 continuously for minutes on end with a class 4 card, and at the highest jpg quality it was just fine. Cameras have internal buffer for this reason and it is simply not a problem. I appreciate where you are coming from, but DonnaA should not spend time on this at all. Any class4, 6, or 10 card will be perfectly capable of keeping up.

So that it's clear to everyone, this scanner is now in DonnaA's possession and, if all goes well, will soon be in Haiti. Here's a blog post about the project:

http://www.diybookscanner.org/news/?p=207

Awesome! I consider projects like these a great defense against those juvenile politicians and lawyers who think copying projects are just about p1rating free b00kz, hur hur hur. So was that last photo in the post a pic of the hospital actually using your scanner? So this version has external lighting?

rob wrote:Awesome! I consider projects like these a great defense against those juvenile politicians and lawyers who think copying projects are just about p1rating free b00kz, hur hur hur. So was that last photo in the post a pic of the hospital actually using your scanner? So this version has external lighting?

That's in Denver, they're prepping it and testing it now for shipping to Haiti, and yep, it has the lighting system I described here, designed to run off a car battery for a whole day.

I'm sure we'll get a bunch of shots of it in operation at the hospital, at least ones telling us all the things that go wrong with it.

dear daniel,

somewhere in this topic you mentioned posting plans for this build and i was wondering if you were considering doing so anytime soon, or, if not full plans, at least more information about some of its parts. i can't figure out the platen-raising system from the various photos available and i'm not completely sure about the cradle-moving system either. i sense that a fair number of forum members live in the academic ecosystem and thus have time in the semester break to get projects like this going, definitely the case with me (back to teaching 1/19), so sooner posting would be nice. i'm excited about the portability of this generation of the scanner, as it would be great to build a machine for use now that could also feasibly be taken around to historical archives (for the very few that would permit its use) when i enter the research phase of a planned history degree next winter.

either way, happy holidays to you and all on the forum

reg gilbert