Auto teleconverter, 20D, and manual lens

Discussion in 'Digital Photography' started by jess, Nov 26, 2005.

  1. jess

    jess Guest

    I got a Kenko 300 Pro 300 2X converter the other day. It works fine
    with all non-"S" lenses, but when I try to use it with my 1000mm
    Maksutov-Cassegrain mirror lens (wholly manual) I get an "Err 01".
    If I count the mirror tele directly on the 20D it works fine.
    I can prevent the error message by putting a small piece of insulating
    material (paper, plastic) over the 20D contacts, but it makes me
    nervous to stick foreign objects inside the camera body. I assume I
    could get the same effect by taping over the contacts on the rear of
    the Kenko, but I haven't tried that.

    I've Googled the problem and searched this group but can't find
    anything useful. http://photonotes.org/articles/eos-manual-lenses/
    recommends "unlock and rotate the lens and TC", but moving around
    with an unlocked lens makes me even more nervous than insulating the
    contacts.

    Anyone here have this experience? Any recommendations (other than
    buying a 600mm "L" lens that I can't afford and using a 3X
    converter)?
    jess, Nov 26, 2005
    #1
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  2. jess

    Bill Funk Guest

    On 26 Nov 2005 10:06:22 -0800, "jess" <> wrote:

    >I got a Kenko 300 Pro 300 2X converter the other day. It works fine
    >with all non-"S" lenses, but when I try to use it with my 1000mm
    >Maksutov-Cassegrain mirror lens (wholly manual) I get an "Err 01".
    >If I count the mirror tele directly on the 20D it works fine.
    >I can prevent the error message by putting a small piece of insulating
    >material (paper, plastic) over the 20D contacts, but it makes me
    >nervous to stick foreign objects inside the camera body. I assume I
    >could get the same effect by taping over the contacts on the rear of
    >the Kenko, but I haven't tried that.
    >
    >I've Googled the problem and searched this group but can't find
    >anything useful. http://photonotes.org/articles/eos-manual-lenses/
    >recommends "unlock and rotate the lens and TC", but moving around
    >with an unlocked lens makes me even more nervous than insulating the
    >contacts.
    >
    >Anyone here have this experience? Any recommendations (other than
    >buying a 600mm "L" lens that I can't afford and using a 3X
    >converter)?


    You seem to have found a workaround.
    Since the lens is wholly manual, it's reasonable to expect there to be
    no contacts on the lens to mate with the contacts on the converter,
    right? Then, what would cause the error message? It seems that a short
    across the contacts on the converter would do that, and the paper
    insulates them from any metal on the lens.
    So, if the problem is that there's some metal on the lens bridging
    contacts on the converter, a solution would be to either grind some
    metal off the lens, or use paper to insulate the contacts from the
    lens.
    Will this do it?

    --
    Bill Funk
    Replace "g" with "a"
    funktionality.blogspot.com
    Bill Funk, Nov 26, 2005
    #2
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  3. jess

    jess Guest

    Yes, I have a workaround, but it doesn't make me very happy. I
    suppose I could crate a small plastic insulator; this would at least
    prevent small pieces of paper detritus from floating onto the sensor.
    I was hoping that there was an undocumented option in the 20D that
    would tell the camera "ignore the lens information ... a manual lens
    is mounted."

    The thing that confuses me is that the contacts on the teleconverter
    appear to mirror those on the camera. If the contacts on the camera
    are shorting, why not the contacts on the converter? If I mount the
    cmara directly to the telescope, I get "00" displayed as an
    aperture but am able to meter and take pictures. With the
    telescope/converter/camera combination I get "Err 01" and no
    picture when I trip the shutter.

    It's almost as though the camera is communicating with the converter
    but not getting the information it expects, so the error occurs. I
    have not tried insulating the contacts on the converter to see if that
    solves the problem ---I'll do that tonight. As far as I can tell the
    contacts on the converter are not touching anything conductive on the
    lens (actually, it's the T-adapter that couples the camera (or
    converter, if I'm using it) to the telescope.

    I don't like the idea of grinding metal off of anything, so I guess
    I'll just stick with an insulating shim. Thanks for the suggestion,
    though.
    jess, Nov 27, 2005
    #3
  4. On 26 Nov 2005 10:06:22 -0800, "jess" <> wrote:

    >I got a Kenko 300 Pro 300 2X converter the other day. It works fine
    >with all non-"S" lenses, but when I try to use it with my 1000mm
    >Maksutov-Cassegrain mirror lens (wholly manual) I get an "Err 01".
    >If I count the mirror tele directly on the 20D it works fine.
    >I can prevent the error message by putting a small piece of insulating
    >material (paper, plastic) over the 20D contacts, but it makes me
    >nervous to stick foreign objects inside the camera body. I assume I
    >could get the same effect by taping over the contacts on the rear of
    >the Kenko, but I haven't tried that.
    >
    >I've Googled the problem and searched this group but can't find
    >anything useful. http://photonotes.org/articles/eos-manual-lenses/
    >recommends "unlock and rotate the lens and TC", but moving around
    >with an unlocked lens makes me even more nervous than insulating the
    >contacts.
    >
    >Anyone here have this experience? Any recommendations (other than
    >buying a 600mm "L" lens that I can't afford and using a 3X
    >converter)?


    Try this google. It covers taping and that's what most do to fix your
    problem.

    http://www.google.com/search?hl=en&q=taping teleconverter contacts


    *********************************************************

    "I have been a witness, and these pictures are
    my testimony. The events I have recorded should
    not be forgotten and must not be repeated."

    -James Nachtwey-
    http://www.jamesnachtwey.com/
    John A. Stovall, Nov 27, 2005
    #4
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