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A comment on Imaging Without Lenses. Parent comment

Re:Imaging Without Lenses by sp332 on Monday February 05, 2018 @12:17PM (#16310264)
I can't quite visualize the problem. As long as you make the focal length of the first cylinder equal to the distance to the second cylinder + the distance from there to the sensor, and make the focal length of the second cylinder just the distance to the sensor, then both dimensions should converge at the right point?
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Re:Imaging Without Lenses by hliyan on Monday February 05, 2018 @12:29PM (#16310334)
I thought so too. But apparently that doesn't give you a _point focus_, rather a square focus, which doesn't work.
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Re:Imaging Without Lenses by sp332 on Monday February 05, 2018 @12:36PM (#16310374)
Ok, I get it. A circular mirror focuses all directions equally, while two cylindrical ones focus only exactly left-right and exactly up-down correctly, leaving every diagonal out of focus to varying extents.
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