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I was wondering if a CMOS will work without its lenses, I want to install a pinhole instead of the lenses, something like this: Fig.1 Matrix=CMOS. Will still work?

Jogarama
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1 Answers1

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Will a more or less focused image be projected onto the sensor?

Sure, as much as any other pinhole camera. Keep in mind that the smaller the pinhole, the less blurry the projected image will be. The larger the pinhole, the blurrier the projected image will be.

Will the projected image be bright enough to produce a usable photo?

If the hole is small enough to provide a sharp enough image to survive the significant enlargement ratio from a small smart-phone camera's sensor to a typical display size and still look "focused", it's probably going to be so small as to not allow enough light through to overcome the signal-to-noise limitations of such a small sensor unless you're working in very bright light, as in even brighter than outdoors in direct sunlight.

Michael C
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    "the smaller the pinhole, the less blurry the projected image will be" is only true to a point. after that diffraction will take its toll. – BobT Jun 12 '23 at 13:29
  • With pinholes, the effect of diffraction is much less than the effect of a wider aperture until well past the point where any usable light is allowed to pass unless one is exposing for hours. – Michael C Jun 13 '23 at 01:06
  • for such cameras, it might be better to use a camera obscura technique where you back-photograph an enclosed screen like parchment paper. – dandavis Jun 15 '23 at 17:29
  • Michael C, no, this is not correct. For 50mm "focal" length, the optimal pinhole size is 0.30–0.35 mm, which means the shutter speed for ISO 100 is just 1 second on a sunny day or 5–20 seconds in overcast conditions. So, BobT's is right. – Ankor Jun 16 '23 at 03:25
  • @Ankor At that point the question is whether exposure times measured in seconds instead of hundredths of seconds are usable or not. – Michael C Jun 16 '23 at 07:18
  • @Ankor The other question is how much any diffraction is noticeable. "Optimal" only applies if one is enlarging and viewing at high magnification, such as 100% (one image pixel = on screen pixel that can be resolved by the viewer) with digital or large enough to see individual grains of film. Since the size of film grain (or pixelpitch) can vary significantly, there is no specific "optimal" size unless one knows the size of the film's grain or the sensor's pixel pitch. If the effect of diffraction is less than the size of a film grain or digital sensel, then it is not detectable. – Michael C Jun 16 '23 at 07:28
  • @MichaelC, no, that's wrong again. "Optimal" in terms of resolution is the same for any sensor and any magnification; the resolution of a pinhole picture is very, very low, so virtually any sensor or film capture all the details. How exactly, in your opinion, optimal aperture depends on the pixel pitch? About usability of 1 s exposure, I just answered to your point that diffraction is visible only when you are exposing for hours — that's simply not true, as I've shown. – Ankor Jun 16 '23 at 15:09
  • I remember experimenting with a pinhole camera in elementary school. We were never given any guidance on what the appropriate exposure time should be, so all our pictures came out completely blank. – Mark Ransom Jun 17 '23 at 03:51
  • The formulae used to define "optimal" are not based on pinhole cameras. They're based on cameras using refractive optics. Applying formulae developed for refractive optical systems to a pinhole camera does not change the fact that the threshold where those formulae place 'acceptably in focus' is based on refractive optics, not pinholes. – Michael C Jun 19 '23 at 08:49
  • @Ankor "'Optimal' in terms of resolution is the same for any sensor and any magnification." Nope. Totally incorrect. Viewing conditions always determine how many degrees/minutes/seconds of arc at the imaging plane can be resolved by the viewer at a specific enlargement/display size and viewing distance. Any calculations which do not specify display/viewing conditions are based on an assumption of "standard" display/viewing conditions: 8" on the short side of the frame viewed at a distance of 10" by a person with 20/20 vision. – Michael C Jun 19 '23 at 08:54
  • @MichaelC, well, absolutely wrong messages again. "The formulae used to define "optimal" are not based on pinhole cameras" — that's a lie, the formula is designed specifically and only for pinhole cameras, it's a tradeoff between diffraction and the fact that resolution linearly decrease with aperture diameter increasing. It makes absolutely no sense for refractive optics, it's correct for pinholes and pinholes only. – Ankor Jun 20 '23 at 18:00
  • @MichaelC, "Any calculations which do not specify display/viewing conditions are based on an assumption of "standard" display/viewing conditions" — no, that's a gross misunderstanding on your side. Viewing conditions don't alter optimal aperture size, because we choose the aperture size to maximize the resolution on the film plane. Then, after printing, in any viewing conditions you can't achieve result better than this, because any other pinhole size will lead to lower resolution. In some display conditions you won't be able to see the difference, but you can't achieve better result. – Ankor Jun 20 '23 at 18:04
  • "Optimal size" based on film plane resolution only applies if the magnification is great enough to see pixel/film grain level differences. Very few display/viewing conditions meet that requirement. If they do, then you didn't have enough pixels/film grains for your intended usage. – Michael C Jun 21 '23 at 00:27
  • @MichaelC, no, resolution of a pinhole is so low, that with any magnification the eye resolution exceeds it, so the "optimal size" applies. Film grain size plays no role, because resolution of any film is much higher than one of a pinhole. So, even if we'd have film with an infinite resolution, it doesn't matter, the "optimal size" of a pinhole stays the same. With ultra low resolution film you won't be able to see the difference between the optimal size and some other size, but with any film, under any conditions you can't achieve better result, only the one that's not worse. – Ankor Jun 27 '23 at 01:00