Correct name for "pinhole lens" used in covert cameras?

Discussion in 'Digital Photography' started by Alison J, Jun 13, 2009.

  1. Alison J

    Alison J Guest

    Can I ask you specialists some questions about digital cameras.

    I want some info on the optical quality of the lenses used in small
    digital camera units lie this:

    Many sites call that a "pinhole lens" but when I search for
    "pinhole lens" I get hits for lenses created by making a pinhole in
    a card.

    Is this tiny glass or plastic lens more correctly called by some
    other term which I can use for a search?

    Thank you.

    PS---I would appreciate any links to info on the typical optical
    quality and specification of these lenses. (Usual angle of view,
    typical low light sensitivity, depth of focus, etc.) I can guess
    these are probably low spec but how low?
    Alison J, Jun 13, 2009
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  2. Alison J

    John Navas Guest

    When you use URL redirection without preview you'll lose much of your
    audience, since that's how spammers and scammers work. Instead:
    Try "pinhole camera"
    John Navas, Jun 13, 2009
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  3. Alison J

    Guest Guest

    or just use the original url. if it's properly delimited with angle
    brackets, it can span multiple lines and remain clickable.
    Guest, Jun 13, 2009
  4. Alison J

    Matt Ion Guest

    You can search on "pinhole camera", as Navas suggests (and in fact, as
    is suggested by the title of the page you linked to), or you can add
    "CCTV" to your original search:
    Matt Ion, Jun 13, 2009
  5. Alison J

    daveFaktor Guest

    The camera is known as : "Camera Obscura" Not sure it that's spelt
    correctly but it sound right.
    daveFaktor, Jun 13, 2009
  6. Alison J

    PatM Guest

    You are hurting my brain, but IIRC that type of lens is called a
    "Pancake Lens".
    PatM, Jun 14, 2009
  7. Alison J

    Matt Ion Guest

    That is spelled correctly, but that's not what he's talking about.
    That's what his searches keep finding, it's not what he's looking for.
    Matt Ion, Jun 14, 2009
  8. Alison J

    dj_nme Guest

    That's called "'pinhole lens" because the hole the video camera needs
    for it's lens to poke through is very small, it looks a bit like a
    pinhole and can sometimes be concealed behind a pop-rivet or what looks
    like a hole left by a missing srew.
    The lens could perhaps be better described as an "afocal lens", because
    everyting appears to be in focus (or at least equally blurred) and thus
    does not need to be focused during installation.
    dj_nme, Jun 14, 2009
  9. Alison J

    PatM Guest

    Here is the DSLR version of a pancake lens, which they say in
    knicknamed a pin lens:

    It might be what you are looking for.
    PatM, Jun 14, 2009
  10. Alison J

    Bob Larter Guest

    Bob Larter, Jun 14, 2009
  11. Alison J

    John Navas Guest

    Not necessarily -- it will still be broken in many news clients.
    John Navas, Jun 14, 2009
  12. Alison J

    John Navas Guest

    While most relatively large lenses aren't at their best wide open, the
    better ones are quite close, with superb optical quality, and at their
    best closed down by only 2-3 stops, which contradicts your claim. And
    their worst performance may well be stopped all the way down due to
    John Navas, Jun 14, 2009
  13. Alison J

    Guest Guest

    then the news client is broken. this is 2009, it's time to update.

    plus those services don't necessarily maintain the url reference
    forever and if someone finds the post on google groups some time in the
    future, the link will be dead and they'll have no way to load the page.
    Guest, Jun 14, 2009
  14. Alison J

    John Navas Guest


    I deal with the world as it is, not what I'd like it to me,
    but as always, YMMV.
    John Navas, Jun 14, 2009
  15. Alison J

    Guest Guest

    translated: i'm stuck using primitive software and refuse to upgrade.
    Guest, Jun 14, 2009
  16. Alison J

    Paul Furman Guest
    It's inherently going to be a very small low resolution camera requiring
    bright light to form an image through a tiny hole. Tiny hole means tiny
    amount of light. Even if you could focus such a lens on the sensor of a
    high performance camera, diffraction would limit resolution severely.
    Tru pinhole photography requires very long exposures due to the tiny
    amount of light passing.

    This one for example:
    1/3" CCD Image Sensor (4.8mm x 3.6mm, the very smallest)
    512 x 492 pixels
    Min Illumination: 0.1 Lux
    Lens Pin Hole: 5.5mm, f/3.5
    Size: 32mm x 32mm

    Probably a clear glass/plastic cover, an open pinhole would let dust in.
    The diagonal of that sensor is 6mm so the 5.5mm lens is a normal lens,
    with a field of view comparable to a 50mm lens on a 35mm format camera.
    The aperture of f/3.5 means 5.5/3.5 = 1.6mm diameter opening. That's
    probably too big for an actual pinhole so perhaps there is an actual
    lens in there. If so, it's probably nothing fancy because diffraction
    will wipe out most of the detail anyways. It wouldn't be worth putting a
    better sensor in there either.

    I have a pancake lens for 35mm format, the opening is 16mm dia. which is
    45mm f/2.8 capable of very high resolution images in low light.

    Paul Furman

    all google groups messages filtered due to spam
    Paul Furman, Jun 14, 2009
  17. Alison J

    Paul Furman Guest

    Go to hell, I was in the ballpark.

    And I doubt there are any infinity focus microscope lenses with a 1.5mm
    dia. front element <g> so you haven't contributed anything here but
    bile, as always.

    While it may be technically possible to get more resolution from such a
    tiny lens (I'd estimate 2MP), it's certainly not common. I challenge you
    to find anything with a 1.5mm front opening that captures more than 640
    pixels wide (1/3 of a megapixel) if even that. Go up to a 6mm opening
    (1/4 inch) & you can do a lot better.

    This place lists a 2.6mm diagonal sensor lens that does about 100 lppmm
    but with a sensor that's only 2mm wide, that's not much resolution:
    It's designed for CIF (352×288 pixels - 1/10th of a megapixel) and would
    have a 0.5mm dia. aperture at f/2.8.

    They also list a 1.5mm aperture lens 'for Mega" presumably meaning a 1
    megapixel sensor 4.8mm wide which is perhaps just barely possible at 80

    Paul Furman

    all google groups messages filtered due to spam
    Paul Furman, Jun 15, 2009
  18. Alison J

    Bob Larter Guest

    This is a complete & utter load of bullshit. Cheap Chinese laser
    pointers do not use >75mW rated laser diodes. Attempting to put that
    much power through one will kill it stone dead instantly. You obviously
    don't have the faintest idea how to measure the output of a laser.
    Bob Larter, Jun 15, 2009
  19. Alison J

    Rich Guest

    Leeuwenhoek microscopes (on hand, few that there are) went up to about
    266x. It is theorized he had them up to 500x. In addition, it is
    very possible his lenses were ground aspherical, unlike small
    spherical lenses you can buy today so the correction across the field
    with his would have been superior. Which is how he was able to
    observe small things in detail and even bacteria and detect Brownian
    motion, while those using compound microscopes with spherical lenses
    had no hope of seeing things in that detail, in those days.
    Rich, Jun 15, 2009
  20. Alison J

    Bob Larter Guest

    Rubbish. You're making the whole thing up.
    Bob Larter, Jun 16, 2009
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