@Leavingoldhabits Hi again, I’ve started playing with an Arduino and a light sensor. At the moment all it can do is read the LED light source from the flatbed scanner during the calibration sequence, and record the results.

The N650U has three stages of calibration:

1. It starts with the LED fluctuating between ambient brightness (860) and full brightness (700), then turns off briefly (860)
2. Steady increase from ambient to full brightness.
3. Steady decrease from full brightness back to ambient.

The next step will be to introduce some kind of timestamp for each moment of the recording. Then the hard bit will be to shine a light source onto the sensor so simulate a proper calibration.

I haven’t recorded the calibration on the LiDe 110 yet, but I will. I didn’t realize it when I modified it, but the book says it will scan at 2400x4800dpi which works out to over 550mp for an A4 scan, which dwarfs the 20mp of my mirrorless, lol.

So, when I say “change the image”, I mean the torch does affect the calibration, in the sense that I get different patterns of stripes based on the position of the torch, but it’s still just outputting stripes.

Here are two scans I made by waving the torch around randomly during the calibration, then resting the torch on the glass.

For some reason each pixel is just outputing the same brightness for the whole duration of the scan, except for that black spot where the torch is, which is weird.

I managed to change the image by just shining a torch into it during the calibration and the scan. This is exciting, I might be making progress :-)

@Leavingoldhabits Hi again, can I ask you some technical questions? I’m struggling modify my scanner. I’ve removed the clips holding the PCB, and I even made a test scan in that state, and it still worked. Then I spent hours milling out the pinhole array. But when I assembled it again, I get weird scans.

I have modified two different scanners. LiDe 110 - I get a tall narrow PNG file with some digital noise. I assumed I damaged the sensor, or a ribbon cable or something, so I shelved it, and looked for another scanner.

N650U - I took more care modifying this one. I get a full width PNG file, but it has a narrow strip of white on one side, and black everywhere else. I wonder if it is related to the initial calibration that it does before scanning. I left the LED in tact, but I removed the prism, so maybe it’s lighting up just that one end of the calibration strip?

Did you have any calibration problems? Have you encountered anything like this? Do you have any advice?

Thanks

I love your post, I’ve been thinking of ways to capture images from large format lenses, and you inspired me to start experimenting with flatbed scanners.

I’m using a Canon N 650U because I had one lying around. I haven’t modified it, so the light source still exists.

I’m genuinely surprised how easy it is to get an image. I experimented by putting the scanner directly under the ceiling light in my kitchen, and I can hold the lens over the flatbed and see the image forming well enough that I can get it into focus. Then just hit the scan button and tada, one image of a ceiling lamp. I didn’t need to dismantle the scanner, or use a gg screen or anything. It just works with the scanner and the lens.

Since then I’ve rigged up a system to hold the lens in place, and a slider to move it up and down to focus. And I drape a cloth over everything to keep stray light off the sensor.

Exposure is difficult. My large format lenses don’t have any aperture control, so I either have to build one, or use an ND filter. Or if I don’t have enough light, I add more continuous light sources.

I saw your comment about vignetting, but I didn’t understand it at the time. I’ve mostly been experimenting with a lens that creates a 100mm image circle, and it works fine. But with another lens, I’ve just tried to scan the entire A4 surface, and the corners are black with a small image in the centre, even though I can peer under the curtain and see a nice bright image from the lens that covers the whole flatbed. I concluded that the sensor will only accept light from one direction, and can’t see light arriving from an angle. So, yeah I’m considering surgery to fix the aperture slit in front of the sensor. I don’t really know what to expect when I open it up. Did you find it easy to remove and modify? Can you offer any advice before I get elbow deep in scanner parts?

Also, my images all come out in black and white, which is weird. Objects sitting on the glass come out in colour, but the image formed by the lens scans in black and white only.

The whole rig is too heavy to pick up right now, so I mounted a little mirror on top, so I can point it anywhere, lol.