Zeiss on Canon

Discussion in 'Canon' started by piterengel, Oct 6, 2008.

  1. piterengel

    J. Clarke Guest

    Your point being?
    J. Clarke, Oct 21, 2008
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  2. piterengel

    Eric Stevens Guest

    You do. That's the origin of the Nikon CPU lens.

    The camera knows whether or not its focused but without a message sent
    back by the lens it has no idea of the range at which it is focused.
    The later Nikon cameras use that information for some of the things
    they do with exposure.

    Eric Stevens
    Eric Stevens, Oct 21, 2008
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  3. piterengel

    Paul Furman Guest

    OK, yeah, that's for ttl flash metering. The bigger reason for Nikon
    chipping of old lenses is that many Nikon models will refuse to meter at
    all without a chip on the lens, but it's my understanding all Canon
    models will meter with any lens (maybe not ttl flash metering though).

    There are some other issues with knowing the max aperture (assuming you
    have an aperture linkage, not doing stop-down) where there's a little
    adjustment made for vignetting on fast lenses, and this is given as a
    reason not to allow 3D matrix metering but I think that's BS. Most of
    the chipping as I understand involves throwing any random cpu from an
    old broken lens in there to fool the camera. This isn't really going to
    give useful information but as I said, it doesn't matter that much and
    generally works fine... maybe a little exposure compensation needed when
    shooting wide open on a fast lens.

    Paul Furman

    all google groups messages filtered due to spam
    Paul Furman, Oct 22, 2008
  4. piterengel

    Paul Furman Guest

    The little green AF confirm light works fine with a D200 & up, and I
    recall reading that it works on any Canon body. Lower Nikon models will
    not meter (probably need to put in manual mode?) but I thought the AF
    confirm works.

    Paul Furman

    all google groups messages filtered due to spam
    Paul Furman, Oct 22, 2008
  5. Unfortunately, this is not true with Canon. AF confirmation needs
    a chip (I dunno why, seems stupid to me, unless you have real fun
    with focus shift due to aperture changes) at least with the 20D.

    But then, maybe the reasoning goes like "If you use manual focus
    lenses, exchange your ground glass fo a third party offer, which
    causes some metering problems of it's own."

    Wolfgang Weisselberg, Oct 22, 2008
  6. Not all Canon lenses (that includes the 50mm f/1.4) return focus
    distance information, still TTL flash metering works. Only for
    direct flash focussing distance can be a help, for indirect flash
    you are outta luck anyway. :)

    Wolfgang Weisselberg, Oct 22, 2008
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