Trap Focus with manual lens

Discussion in 'Digital Cameras' started by Sandman, Sep 4, 2013.

  1. Sandman

    Sandman Guest

    Blog:
    <http://jonaseklundh.se/pages/Trap_Focus_Med_Manuell_Lins?lang=en>


    Trap focus doesn't work with manual lenses for Nikon (or Canon as far
    as I'm aware). Trap focus is a method where you set the camera to
    focus on a specific spot and as soon as it detects focus on something
    entering that zone, it fires of an exposure. Unfortunately, this
    requires an autofocus lens for unknown reasons. The camera is
    perfectly capable to detect whether or not there is an object in focus
    on a manual lens, but it won't let you expose only if such an event
    occurs. When depressing the shutter button on a manual lens, it always
    fires of a shot.

    But, there is a solution in the shape of an AF-chip that you glue on
    to the manual lens. I have a Lensbaby Composer Pro and the reason I
    want to use trap focus is because the lenses for the Lensbaby
    sometimes heavily distorts the image in the viewfinder so it's hard to
    determine whether or not you're in focus or not. But the camera knows,
    most of the time at least! So I ordered a Dandelion chip and here are
    the steps to mount it.

    <http://jonaseklundh.se/aimg202072.jpg>

    For reference, here's the connection of a normal lens

    <http://jonaseklundh.se/aimg202071.jpg>

    This is my Composer Pro, lacking the above connections since it's a
    manual lens.

    <http://jonaseklundh.se/aimg202073.jpg>

    These are the parts that came in the Chip kit. A template for
    placement and a small plastic mounting bracket when needed.

    <http://jonaseklundh.se/aimg202067.jpg>

    The chip was glued to the plastic mounting part, which was needed in
    my case since the Composer Pro has a part of the metal missing where
    the chip should be mounted.

    <http://jonaseklundh.se/aimg202066.jpg>

    Then I removed the mounting piece from the lens and with the template
    I glued the chip. The template slides in to a grove on the lens which
    ensures that the chip is placed 100% correct.

    <http://jonaseklundh.se/aimg202064.jpg>

    Then I assembled it all together, and here's how it looks

    And it works! The camera now thinks it has a autofocus lens mounted,
    and won't fire off the shutter unless it detects focus. Sure, it
    requires some practicing, since you can overshoot the focus point
    since you are focusing manually, but I'm very pleased!
     
    Sandman, Sep 4, 2013
    #1
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