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I'm only just learning tonight how to interpret camera specs, and I'm feeling a little frustrated. I have a project in mind that will require me to film a 6x6" (15 x 15 cm) view up-close at +/- 30 fps - preferably less than 1" (2.5 cm) away from the lens.

I am okay with fisheye lenses, I do not need a rectilinear lens and think I can correct the distortion in post. The camera will be underneath a glass plate and will film objects that sit on the glass plate. Form factor constraints require that the glass plate be that close to the camera.

After looking around, I can't find any USB camera modules that can accomplish this off the shelf. I'm hoping that I am just misunderstanding the specs and that someone can point me to a USB camera module that will meet my requirements.

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    \$\begingroup\$ You are asking for essentially a 180 degree field of view. If the center of the frame is 1 inch from the lens the corners will be about 3 1/8 inches so there will be considerable distortion. It is unlikely you can get that much depth of field, so something will be very blurred. Maybe you should describe the project and we can help with the plan. \$\endgroup\$ Feb 17, 2022 at 6:12
  • \$\begingroup\$ Thanks @RossMillikan. The camera is underneath a glass plate and photographing objects that sit on the glass plate. Form factor constraints require that the glass plate be that close to the camera. The 6"x6" field is also a constraint. \$\endgroup\$
    – user20672
    Feb 17, 2022 at 6:24
  • \$\begingroup\$ I'm okay with fisheye distortion, for what it's worth. I think I should be able to correct it in post-processing to some extent \$\endgroup\$
    – user20672
    Feb 17, 2022 at 6:25
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    \$\begingroup\$ Are the objects flat surfaces or three-dimensional objects? \$\endgroup\$ Feb 17, 2022 at 9:08
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    \$\begingroup\$ Also curious what kind of moving objects will sit on the glass plate. Perhaps a camera array is an option, where each unit captures a small part of the object? This previous question is about reducing the minimum focusing distance of a camera, perhaps it's helpful. \$\endgroup\$ Feb 17, 2022 at 10:55

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The camera and lens will have some depth themselves so you need even more vertical space under the glass plate. My suggestion would be to employ a folding mirror. Place a mirror under the glass plate at 45 degrees and then the camera is placed imaging parallel to the glass plate. This allows a long focal length which will make images easier to use and probably more in focus. You can make the vertical size even shallower with two cameras and two folding mirrors each imaging half the glass plate.

enter image description here

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  • \$\begingroup\$ Great idea! I was discussing this exact idea with a friend the other day \$\endgroup\$
    – user20672
    Feb 19, 2022 at 19:33
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The following module works for my purposes:

SVPRO 2MP USB Camera Module Fisheye Lens 180 Degree Camera Board Free Driver UVC

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  • \$\begingroup\$ Adding a link would be convenient. \$\endgroup\$
    – Eric S
    Feb 20, 2022 at 1:19
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For still photography an ordinary flatbed scanner can accomplish that over USB.

The subjects will sit on a glass plate as well.

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  • \$\begingroup\$ Thanks! It's a real-time application (~30fps). My understanding of flatbed scanners is that they would not be able to accommodate that. \$\endgroup\$
    – user20672
    Feb 17, 2022 at 7:32
  • \$\begingroup\$ @user20672 30fps sounds like video. \$\endgroup\$ Feb 17, 2022 at 11:31
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I doubt it. Imho it is not feasible.

The lens needs to be very close. So it needs to focus very close. But at the same time, you want to focus 6 times further away. I also think that that kind of distortion will be too extreme to correct. And you want to correct every single frame? You also need to illuminate the object.

Probably you can construct some camera array with some software to stitch images together or increase the distance to the plane.

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  • \$\begingroup\$ A stitched array is a clever idea. \$\endgroup\$
    – Eric S
    Feb 17, 2022 at 22:15
  • \$\begingroup\$ Thanks! I bought a 180-degree fisheye lens with a very short focal length. I'll let you know how it goes. \$\endgroup\$
    – user20672
    Feb 18, 2022 at 21:29
  • \$\begingroup\$ Please! it will be interesting! \$\endgroup\$
    – Rafael
    Feb 18, 2022 at 22:01

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