Daniel Reetz, the founder of the DIY Book Scanner community, has recently started making videos of prototyping and shop tips. If you are tinkering with a book scanner (or any other project) in your home shop, these tips will come in handy. https://www.youtube.com/channel/UCn0gq8 ... g_8K1nfInQ

Sola Technical's $70 acrylic scanning platform on Ponoko

Built a scanner? Started to build a scanner? Record your progress here. Doesn't need to be a whole scanner - triggers and other parts are fine. Commercial scanners are fine too.
vitorio
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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Post by vitorio » 13 Feb 2012, 13:10

No, you pick it up with your hands. Gingerly.

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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Post by goldo » 13 Feb 2012, 17:33

yes but, in order to turn the pages of the book, does the v-shape stay in contact with others plastic elements ? Or do we need to take it off fully apart of the rest (next to the rest of the other plastic elements) ?

I want a system where I raise the v-shape, turn the page of the book and lowers the v-shape. I will not remove the v-shape completely, place it next to, and replacing it every time every time...

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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Post by vitorio » 13 Feb 2012, 18:48

goldo wrote:I will not remove the v-shape completely, place it next to, and replacing it every time every time...
That's what you would have to do with this one. Sorry.

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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Post by vitorio » 19 Feb 2012, 06:02

I have decided that this scanner is an excellent scanner for someone who wants to learns all of the "why"s of book scanning. Why reflections are important. Why manual focus is important. Why lighting is important. Why angles are important. Etc.

However, if you would like to actually scan books with this scanner (or, I expect, the later model which is now available), I cannot suggest you use it.

With the working blackout tent and lighting complete, I began doing some final tests with varying wattage lightbulbs. It suddenly became painfully clear that the facing pane of the platen was reflecting back onto the page I was taking a photograph of, and also that white facing pages would actually wash out the page I was trying to take a photograph of.

I ended up coloring the facing platen in with a black marker to subdue most reflections, but it's still there if you look closely. Reducing the lightbulb power down to a small 45w flood helped a little as well.

I like these GE "Reveal" incandescent lightbulbs, the color quality (after setting the white balance on the camera) is a little better than normal "soft white" or "decorative" bulbs. With the white balance set properly, there is little difference between wattages above 65w (I tried 100, 150 and 200), and 45w seemed most accurate.

With this Sony DSC-W570 compact camera, I can set the ISO down to 80, set the white balance, have it do multi-point metering, but the "aperture" is a neutral density filter so I can't mess with that. There is also no manual focus. This is killing me, as the camera will occasionally not focus on a page, and it's not always obvious until after I review it. When it is bad enough to be obvious, retaking the picture doesn't help, because it's a failure to autofocus at all.

I'm not sure why this isn't called out whenever people are asking about cameras. If you can't manually focus, scanning a book may be impossible if the autofocus fails. I'm not sure what to do about this, short of putting things on the page to help the camera focus, and then removing them for the shot. Doing that under the platen will be tricky, because I have to walk around the other side of the scanner to take the photo.

I've photographed 20 or so pages and I'm currently going through figuring out Scan Tailor with them.

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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Post by daniel_reetz » 19 Feb 2012, 15:16

vitorio wrote: I like these GE "Reveal" incandescent lightbulbs, the color quality (after setting the white balance on the camera) is a little better than normal "soft white" or "decorative" bulbs. With the white balance set properly, there is little difference between wattages above 65w (I tried 100, 150 and 200), and 45w seemed most accurate.


...There is also no manual focus. This is killing me, as the camera will occasionally not focus on a page, and it's not always obvious until after I review it. When it is bad enough to be obvious, retaking the picture doesn't help, because it's a failure to autofocus at all.

I'm not sure why this isn't called out whenever people are asking about cameras. If you can't manually focus, scanning a book may be impossible if the autofocus fails.
I agree, the Reveals are excellent and I have them on a copystand right now.

As far as the cameras, I called that out in the original Instructable a few years ago but we still have the problem of few current, good camera recommendations and I feel this acutely as the Guy In Charge Or Something. Manual focus should go on the list.

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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Post by Heelgrasper » 21 Feb 2012, 13:15

Before the hacking I had made a post here about the problem might being the distance from camera to platen.

I based that on the fact that a Sony DSC-W570 has a minimum focusing distance of only 5 cm when zoom isn’t used (wide) but 1 meter with the zoom maxed (tele) as seen here: http://www.digitalreview.ca/content/Son ... view.shtml (among other places).

For my good old Canon PowerShot A540 the same numbers are 5 cm and 30 cm and I’ve noticed that as soon as I zoom just a little it seems be 30 cm. So when I have to photograph something small (I often do since I metal detect and find coins about 1 cm in diameter) it’s either no zoom or full zoom where the field covered is almost the same.

Then why use zoom at all? Because with no zoom there tend to be a bit of barrel distortion and I would think that is quite important to awoid when it comes to book scanning. The “problem” for the Canon I have can be seen here: http://www.dcresource.com/reviews/canon ... 40-review/ . It’s pretty easy to test the same way for yourself. I don’t know if it’s an issue with the Sony but without zoom the lens is equal to a 25 mm lens on a good old SLR and that would usually give a bit barrel distortion. Old school rule of thumb was that things look pretty normal at 50 mm.
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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Post by vitorio » 21 Feb 2012, 16:54

Heelgrasper wrote:Before the hacking I had made a post here about the problem might being the distance from camera to platen.

I based that on the fact that a Sony DSC-W570 has a minimum focusing distance of only 5 cm when zoom isn’t used (wide) but 1 meter with the zoom maxed (tele) as seen here: http://www.digitalreview.ca/content/Son ... view.shtml (among other places).

For my good old Canon PowerShot A540 the same numbers are 5 cm and 30 cm and I’ve noticed that as soon as I zoom just a little it seems be 30 cm. So when I have to photograph something small (I often do since I metal detect and find coins about 1 cm in diameter) it’s either no zoom or full zoom where the field covered is almost the same.
Thanks for re-posting!

So, I haven't been able to find exactly what the focus distance is, and I don't see it on the page you linked. Before the hacking, I did some tests and posted some photos, but the gist is:
  • You appear to be correct: once I zoom in, there's a focusing problem. The book is ~16" away from the camera.
  • The focusing problem is irrespective of whether there's acrylic in the way or not, and once I hit the out-of-focus point, zooming in further doesn't help.
  • Without zoom, I can get closer to the page and it still focuses fine. I can't get close enough to not use zoom at all with my current setup, but I am interested in a no-zoom/full-zoom setup now!
  • When zoomed in just a little, it still has trouble focusing sometimes, but not all the time. I have registration marks on white paper taped to the inside of the platen now to help with this, but I haven't tried a full book yet.
Unfortunately, I don't think I'll have time to run through the book this week or this coming weekend. Maybe next weekend.

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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Post by Heelgrasper » 21 Feb 2012, 18:01

vitorio wrote: So, I haven't been able to find exactly what the focus distance is, and I don't see it on the page you linked.
It's at the table at the bottom of the page:

Minimum Focusing Distance
iAuto (W: Approx. 5cm to Infinity
T: Approx. 100cm to Infinity)

The 100 cm seems to be a bit much in my eyes but of course most people don't start zooming in if they are closer than 100 cm to object.
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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Post by dpc » 22 Feb 2012, 17:08

Isn't a page being in focus more important for reliable OCR than barrel distortion? Can't barrel distortion be mitigated in a post-process prior to OCR?

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Re: Sola Technical's $70 acrylic scanning platform on Ponoko

Post by Heelgrasper » 22 Feb 2012, 17:20

The page in focus is a must. Barrel distortion you live with or perhaps deal with in postprocessing. But you will still have to live with having to move the camera quite close if it's a small book and you want it to fill out the picture. I just tried real quick and it looks like a distance of roughly 9 inches between camera and platen if you want to scan a book with a page size of 6 x 8.5 inches (small but not unheard of). I would think that in a lot of configurations 9 inches is a bit problematic.

And there's no reason that it should be an issue. When my rather old cam can manage going as close as 30 cm at full zoom, why should new models need 100-120 cm?
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