Re: Infrared photography

Discussion in 'Digital Photography' started by phil-news-nospam@ipal.net, Sep 28, 2008.

  1. Guest

    In rec.photo.digital DaveC <> wrote:

    | I want to photograph and video in infrared mode.

    I'd like to know the spectral range possibilities of various sensors, both
    in how long they can go for IR, and how short they can go for UV (assuming
    the filter on the sensor is removed or replaced). I have heard figures of
    1000nm and 1200nm for IR, but no figures for UV.

    Are there cameras with special sensors that go well beyond what normal cameras
    intended for the visible spectrum can do?

    --
    |WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
    | by the abuse department, bellsouth.net is blocked. If you post to |
    | Usenet from these places, find another Usenet provider ASAP. |
    | Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |
     
    , Sep 28, 2008
    #1
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  2. On 28 Sep 2008 03:51:18 GMT, wrote:

    >In rec.photo.digital DaveC <> wrote:
    >
    >| I want to photograph and video in infrared mode.
    >
    >I'd like to know the spectral range possibilities of various sensors, both
    >in how long they can go for IR, and how short they can go for UV (assuming
    >the filter on the sensor is removed or replaced). I have heard figures of
    >1000nm and 1200nm for IR, but no figures for UV.
    >
    >Are there cameras with special sensors that go well beyond what normal cameras
    >intended for the visible spectrum can do?


    When I was searching for IR-ready and UV-ready cameras (I had a penchant to
    photograph all the hidden patterns in plants that insects and other animal
    orders depend on) I found that the Sony "Super-HAD" CCD sensors had the most
    sensitivity to the largest spectrum of IR frequencies, covering the widest
    bandwidth with the most sensitivity (in consumer cameras). You can find the
    spec-sheets on various CCD arrays online. This was (5?) years ago when I did my
    initial research and I'm not about to recreate that for you by Googling it for
    you again. The IR frequencies that you want to expose for on these sensors being
    determined only by the bandpass filter used in front of the lens array. Their
    "Super-HAD" CCDs are conveniently used in all their inexpensive "NightShot" and
    "NightFraming" capable IR-ready consumer P&S cameras.

    Now on the other hand, only one camera out there (no longer available, I don't
    think, and I don't recall who manufactured it because it was prohibitively
    expensive, I didn't even want to think about trying to purchase it) was designed
    to do both IR and UV with the flick of a switch. It was an expensive specialty
    camera manufactured by Canon, Panasonic, or some other popular company, designed
    to sell to research and forensics investigation departments.

    UV is a whole other beast to contend with. Most optical glass in nearly all
    camera lenses is a good absorption filter for many UV wavelengths. Even the
    micro-lens array and Bayer-filter on the sensor is a UV blocking filter to some
    extent. Imaging most of the UV bandwidths requires special and EXPENSIVE lenses
    that will allow transmission of UV to any electronic sensor. Short-wave UV
    transmission is totally obliterated by nothing more than a layer of flint or
    crown-glass as thin as the material in a drinking-glass or standard
    daylight-filter. In high-resolution UV photomicroscopy, for example, it requires
    specialty lens elements made of hard pure-quartz and soft fluorite, throughout
    the whole light-path, from subject to recording medium. Due to the high melting
    point of pure quartz and the difficulty in figuring soft (and easily
    moisture-destroyed) fluorite into the right curves (the reason L-Glass lenses
    are so expensive) you aren't going to easily obtain camera lenses that can
    transmit a wide bandwidth of UV with most consumer's bank-accounts. Most CCD
    cameras will be somewhat sensitive to the long-wave UV spectrum, but only some
    of it. Limited by the very optics that are a part of all white-light-imaging
    lens assemblies. Long-wave UV, yes, you can reach into that bandwidth somewhat
    successfully with standard lenses and common CCD sensors, but don't even think
    about imaging in the short-wave UV spectrum with any of the standard glass lens
    elements available on the market. Even L-Glass lenses are incapable for this use
    because they are a mixture of more-common glasses elements plus fluorite
    elements. The standard flint and crown glass components (as archaic examples
    only, there are hundreds, if not thousands of modern glass recipes) will quickly
    filter-out any short-wave UV that the L-Glass lenses' few fluorite elements
    might pass.
     
    carlislestamford, Sep 28, 2008
    #2
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  3. Guest

    In rec.photo.digital carlislestamford <> wrote:

    | UV is a whole other beast to contend with. Most optical glass in nearly all
    | camera lenses is a good absorption filter for many UV wavelengths. Even the
    | micro-lens array and Bayer-filter on the sensor is a UV blocking filter to some
    | extent. Imaging most of the UV bandwidths requires special and EXPENSIVE lenses
    | that will allow transmission of UV to any electronic sensor. Short-wave UV
    | transmission is totally obliterated by nothing more than a layer of flint or
    | crown-glass as thin as the material in a drinking-glass or standard
    | daylight-filter. In high-resolution UV photomicroscopy, for example, it requires
    | specialty lens elements made of hard pure-quartz and soft fluorite, throughout
    | the whole light-path, from subject to recording medium. Due to the high melting
    | point of pure quartz and the difficulty in figuring soft (and easily
    | moisture-destroyed) fluorite into the right curves (the reason L-Glass lenses
    | are so expensive) you aren't going to easily obtain camera lenses that can
    | transmit a wide bandwidth of UV with most consumer's bank-accounts. Most CCD
    | cameras will be somewhat sensitive to the long-wave UV spectrum, but only some
    | of it. Limited by the very optics that are a part of all white-light-imaging
    | lens assemblies. Long-wave UV, yes, you can reach into that bandwidth somewhat
    | successfully with standard lenses and common CCD sensors, but don't even think
    | about imaging in the short-wave UV spectrum with any of the standard glass lens
    | elements available on the market. Even L-Glass lenses are incapable for this use
    | because they are a mixture of more-common glasses elements plus fluorite
    | elements. The standard flint and crown glass components (as archaic examples
    | only, there are hundreds, if not thousands of modern glass recipes) will quickly
    | filter-out any short-wave UV that the L-Glass lenses' few fluorite elements
    | might pass.

    What about plastic lenses we ordinarily would scoff at? There are some better
    quality plastic materials these days. Maybe it could be a semi-useful, even
    if not the best quality, lens specific for shorter UV that you could ever hope
    to get out of glass, without having to mess with quartz.

    --
    |WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
    | by the abuse department, bellsouth.net is blocked. If you post to |
    | Usenet from these places, find another Usenet provider ASAP. |
    | Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |
     
    , Sep 28, 2008
    #3
  4. On 28 Sep 2008 07:48:25 GMT, wrote:

    >
    >What about plastic lenses we ordinarily would scoff at? There are some better
    >quality plastic materials these days. Maybe it could be a semi-useful, even
    >if not the best quality, lens specific for shorter UV that you could ever hope
    >to get out of glass, without having to mess with quartz.


    Some acrylics and specialty plastics are indeed exceptional in the visual
    wavelengths. This is why they were so popular in the "almost disposable" 35mm
    and 126-film cameras of the past. Quickly molded in mass numbers with the
    perfect properties and curvatures needed. One or two plastic lens elements
    taking the place of expensive and difficult to figure/assemble
    multiple-component achromat glass arrays, the inexpensive and lightweight
    acrylic lenses preventing nearly all chromatic aberration problems.

    I have not researched how they might be used for IR and UV though. UV might be
    difficult because the carbon-based materials are often fluorescent (or
    absorbing) to particular UV wavelengths. Though I'm sure there must be some
    plastics that would easily fit the bill. I've often thought that many of our
    modern cameras today could benefit greatly from their (plastic lenses')
    properties, especially with chromatic aberrations being a prevalent problem in
    many digital cameras/lenses. Not to mention just the weight benefits and
    cost-savings. I assume they don't incorporate them (on internal lens elements
    only, to prevent abrasions) only because of the marketing aspect of advertising
    "plastic lens components". The average consumer would not understand their vast
    benefits over glass lenses and, as you say, scoff at them. Revealing only their
    ignorance and stupidity.

    There is not a large outcry for UV and IR capable cameras. I would be first in
    line to buy an inexpensive tri-bandwidth (IR, Vis, UV) performer, but I'm the
    exception rather than the rule. I wish my camera to be able to image in all the
    frequencies that could be captured by a CCD array. As well as record audio from
    sub-sonic to ultra-sonic frequencies. Your average person has no concern over
    what they can't see nor sense, out of sight -- out of mind. They have no
    curiosity about something that is beyond their crippled perception of reality.
     
    carlislestamford, Sep 28, 2008
    #4
  5. Guest

    In rec.photo.digital carlislestamford <> wrote:

    | There is not a large outcry for UV and IR capable cameras. I would be first in
    | line to buy an inexpensive tri-bandwidth (IR, Vis, UV) performer, but I'm the
    | exception rather than the rule. I wish my camera to be able to image in all the
    | frequencies that could be captured by a CCD array. As well as record audio from
    | sub-sonic to ultra-sonic frequencies. Your average person has no concern over
    | what they can't see nor sense, out of sight -- out of mind. They have no
    | curiosity about something that is beyond their crippled perception of reality.

    Many years ago I was actually thinking about a design for "an antenna camera"
    to produce some rough imaging of RF frequencies. It would, of course, have to
    be a huge array to get anything approaching a "picture" below the microwave
    frequencies. It might be interesting to do this from a distance "looking" at
    the downtown area of a major city, and merge the 124000000nm to 120000000nm
    view with the 700nm to 400nm view to see all the wifi radiation spots.

    --
    |WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
    | by the abuse department, bellsouth.net is blocked. If you post to |
    | Usenet from these places, find another Usenet provider ASAP. |
    | Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |
     
    , Sep 29, 2008
    #5
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