Canon A20 infrared pictures and focus

Discussion in 'Digital Photography' started by Kim, Sep 8, 2003.

  1. Kim

    Kim Guest

    I got a Hoya R72 infrared filter for my aging Canon A20 and have been
    experimenting with some infrared shots. They come out pretty well when
    there's plenty of sunlight, but everything is always out of focus.
    I've only tried shooting landscapes which would be focused on the distance,
    so I didn't think focusing would be a problem.

    The A20 does not have a manual focus option and sharpening in Photoshop
    doesn't help much.

    Is there anything I can do about this or am I just going to have to get a
    camera with manual focus?
     
    Kim, Sep 8, 2003
    #1
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  2. This may be a bit tricky, but how about setting the focus before putting on
    the filter? That is, depress shutter halfway, put on filter & shoot.

    Juan

    "Kim" <> wrote in message
    news:Xns93F07C610164Bkimwatsonblueyonderc@216.65.98.9...
    > I got a Hoya R72 infrared filter for my aging Canon A20 and have been
    > experimenting with some infrared shots. They come out pretty well when
    > there's plenty of sunlight, but everything is always out of focus.
    > I've only tried shooting landscapes which would be focused on the

    distance,
    > so I didn't think focusing would be a problem.
    >
    > The A20 does not have a manual focus option and sharpening in Photoshop
    > doesn't help much.
    >
    > Is there anything I can do about this or am I just going to have to get a
    > camera with manual focus?
     
    Juan R. Pollo, Sep 8, 2003
    #2
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  3. Kim

    Matt Arnold Guest

    "Juan R. Pollo" <> wrote in message
    news:Xr07b.130962$...
    > This may be a bit tricky, but how about setting the focus before putting

    on
    > the filter? That is, depress shutter halfway, put on filter & shoot.
    >


    This wouldn't work. This is because when you focus, you're using visible
    light wavelengths. When you put the IR filter on, the IR wavelengths are
    longer and will not focus on the CCD with your pre-set focus. There may not
    be much in it, but that method won't produce a fine focus if you're after
    that.

    The only way is to put the filter on and use the manual focus to get it pin
    sharp. But because you've not got a manual focus, you're going to have a
    problem and I'm not sure it's possible.

    Matt Arnold
    Go further with your Fuji cam: http://www.camerashed.co.uk
     
    Matt Arnold, Sep 8, 2003
    #3
  4. "Matt Arnold" <> wrote in message
    news:bji7ru$rnr$...
    >
    > "Juan R. Pollo" <> wrote in message
    > news:Xr07b.130962$...
    > > This may be a bit tricky, but how about setting the focus before putting

    > on
    > > the filter? That is, depress shutter halfway, put on filter & shoot.
    > >

    >
    > This wouldn't work. This is because when you focus, you're using visible
    > light wavelengths. When you put the IR filter on, the IR wavelengths are
    > longer and will not focus on the CCD with your pre-set focus. There may

    not
    > be much in it, but that method won't produce a fine focus if you're after
    > that.
    >
    > The only way is to put the filter on and use the manual focus to get it

    pin
    > sharp. But because you've not got a manual focus, you're going to have a
    > problem and I'm not sure it's possible.
    >
    > Matt Arnold
    > Go further with your Fuji cam: http://www.camerashed.co.uk
    >


    Try stopping the lens down as much as possible... won't cure the problem
    entirely, but will help, in any event.

    - jz
     
    Jeff Zawrotny, Sep 8, 2003
    #4
  5. Kim

    Buster Guest

    If any of you have older still camera lenses, you will notice that
    there is a red mark on the depth of field scale in front of the
    aperture ring. This is the IR offset mark for focus. This is because
    IR does not focus at the same plane as visible light and since you
    can't see it, you can't tell where to focus. On your camera, it is
    using a CCD (not film) designed to see IR and the LCD allows you to
    preview the IR image. I remember shooting IR with film and an 87
    filter. The 87 filter totally blocks visible light. You had to focus
    without the filter, then shift the focus to the red IR mark and
    install the filter. It didn't allow much spontaneous shooting.
    Buster


    On Mon, 08 Sep 2003 22:25:44 GMT, "Juan R. Pollo"
    <> wrote:

    >Hmmm...all this talk about different focusing lengths doesn't make a lot of
    >sense. My Sony vidcam focuses just great when in Nightshot mode, I don't
    >think it uses any special separate IR focusing apparatus. It's the same
    >focus under IR as it is under regular mode.
     
    Buster, Sep 9, 2003
    #5
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