Sensor sizes

Discussion in 'Digital Photography' started by Roger Whitehead, Jul 14, 2006.

  1. I often see these expressed like this: '1/1.8"'. Does this mean it is 1" x
    1.8"?

    That particular sensor is from the Canon PowerShot A620, a P&S camera.

    The sensor in the same maker's EOS 5D dSLR is described as "full frame". I
    understand this to mean it's the same size (more or less) as the image
    area of 35mm film. From memory, that's 24mm x 36mm or 0.95" x 1.4". If my
    supposition above is correct, this is smaller in area than the A620's!

    What's the answer, please?

    Roger
     
    Roger Whitehead, Jul 14, 2006
    #1
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  2. Roger Whitehead

    John Bean Guest

    John Bean, Jul 14, 2006
    #2
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  3. Roger Whitehead, Jul 14, 2006
    #3
  4. Roger Whitehead

    Bill Funk Guest

    On Fri, 14 Jul 2006 16:19:41 GMT, Roger Whitehead
    <> wrote:

    >I often see these expressed like this: '1/1.8"'. Does this mean it is 1" x
    >1.8"?
    >
    >That particular sensor is from the Canon PowerShot A620, a P&S camera.
    >
    >The sensor in the same maker's EOS 5D dSLR is described as "full frame". I
    >understand this to mean it's the same size (more or less) as the image
    >area of 35mm film. From memory, that's 24mm x 36mm or 0.95" x 1.4". If my
    >supposition above is correct, this is smaller in area than the A620's!
    >
    >What's the answer, please?
    >
    >Roger


    Here's a page that explains it pretty well:

    http://www.dpreview.com/learn/?/Glossary/Camera_System/sensor_sizes_01.htm

    --
    Bill Funk
    replace "g" with "a"
     
    Bill Funk, Jul 14, 2006
    #4
  5. Roger Whitehead, Jul 15, 2006
    #5
  6. Roger Whitehead

    Guest

    Roger Whitehead wrote:
    > I often see these expressed like this: '1/1.8"'. Does this mean it is 1" x
    > 1.8"?
    >
    > That particular sensor is from the Canon PowerShot A620, a P&S camera.
    >
    > The sensor in the same maker's EOS 5D dSLR is described as "full frame". I
    > understand this to mean it's the same size (more or less) as the image
    > area of 35mm film. From memory, that's 24mm x 36mm or 0.95" x 1.4". If my
    > supposition above is correct, this is smaller in area than the A620's!
    >
    > What's the answer, please?
    >
    > Roger


    In addition to the other good replies, including the good web site
    reference, there is another historical factor I can bring up. The
    first electronic focal planes showed up in camcorders as soon as they
    did in digicams. Now, historically, the first consumer camcorders used
    vidicon imaging tubes (actually, some of the earliest digicams did too
    (or at least electronic cameras). Vidicons were vacuum tubes, and were
    round cylinders to best withstand the pressure of the vacuum. The
    image format was what would fit on the end of the tube. It was always a
    4:3 ratio, and one could easily figure out what the dimensions were
    from the diameter of the tube, which was essentially the diagonal of
    the 4:3 rectangle. So, we would talk about a 1 inch sensor, which
    could be either a one inch vidicon tube or a CCD chip with a diagonal
    of 1 inch. That is how the diagonal got so much importance in
    specifying image format sizes.
     
    , Jul 16, 2006
    #6
  7. Roger Whitehead

    Prometheus Guest

    In article <>,
    writes
    >
    >Roger Whitehead wrote:
    >> I often see these expressed like this: '1/1.8"'. Does this mean it is 1" x
    >> 1.8"?
    >>
    >> That particular sensor is from the Canon PowerShot A620, a P&S camera.
    >>
    >> The sensor in the same maker's EOS 5D dSLR is described as "full frame". I
    >> understand this to mean it's the same size (more or less) as the image
    >> area of 35mm film. From memory, that's 24mm x 36mm or 0.95" x 1.4". If my
    >> supposition above is correct, this is smaller in area than the A620's!
    >>
    >> What's the answer, please?
    >>
    >> Roger

    >
    >In addition to the other good replies, including the good web site
    >reference, there is another historical factor I can bring up. The
    >first electronic focal planes showed up in camcorders as soon as they
    >did in digicams. Now, historically, the first consumer camcorders used
    >vidicon imaging tubes (actually, some of the earliest digicams did too
    >(or at least electronic cameras). Vidicons were vacuum tubes, and were
    >round cylinders to best withstand the pressure of the vacuum. The
    >image format was what would fit on the end of the tube. It was always a
    >4:3 ratio, and one could easily figure out what the dimensions were
    >from the diameter of the tube, which was essentially the diagonal of
    >the 4:3 rectangle. So, we would talk about a 1 inch sensor, which
    >could be either a one inch vidicon tube or a CCD chip with a diagonal
    >of 1 inch. That is how the diagonal got so much importance in
    >specifying image format sizes.


    Not forgetting that the sensitive target within the tube needed supports
    around it, hence the diagonal of the actual sensitive target was ~2/3 of
    the diameter of the tube. When solid-state sensors where introduced they
    were described by the equivalent tube diameter so that users would know
    which lenses would give correct coverage, i.e. if you have lenses
    designed for a 1 in. tube you would know that they would work with
    camera containing a "1 in. sensor".

    --
    Ian G8ILZ
     
    Prometheus, Jul 16, 2006
    #7
  8. In article <>, Prometheus wrote:
    > Not forgetting that the sensitive target within the tube needed supports
    > around it, hence the diagonal of the actual sensitive target was ~2/3 of
    > the diameter of the tube.


    Thanks, Ian.

    Roger
     
    Roger Whitehead, Jul 16, 2006
    #8
  9. In article <>, wrote:
    > In addition to the other good replies, including the good web site
    > reference, there is another historical factor I can bring up....


    Thanks. An interesting backgrounder.


    Roger
     
    Roger Whitehead, Jul 16, 2006
    #9
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