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Thread: HELP: Not Sure How to Use the 6x7 55mm F4 Lens on 645D

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    HELP: Not Sure How to Use the 6x7 55mm F4 Lens on 645D

    Just purchased this lens and the adaptor for 645D. There is a slide on the lens showing Auto and Manual, I move the slide to the right in the direction of Auto and it springs back to the left towards Manual. Not sure how this works and why its there. Also, I set the F stop manually but it does not show up in the Top LCD on the D, It shows F and No number( Aperture) Can you explain this as well
    Its a gorgeous lens well crafted. Thank you,

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    Re: HELP: Not Sure How to Use the 6x7 55mm F4 Lens on 645D

    Quote Originally Posted by rollsman44 View Post
    Just purchased this lens and the adaptor for 645D. There is a slide on the lens showing Auto and Manual, I move the slide to the right in the direction of Auto and it springs back to the left towards Manual. Not sure how this works and why its there. Also, I set the F stop manually but it does not show up in the Top LCD on the D, It shows F and No number( Aperture) Can you explain this as well
    Its a gorgeous lens well crafted. Thank you,
    Not sure which version you have. The switch is spring loaded, when moving from Auto (visible) to Man, you are stretching the spring. The switch should remain in Man until you press the switch and then the spring returns the switch to auto. F stop will not appear in 645D with the adapter, but open aperture metering functions.

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    Re: HELP: Not Sure How to Use the 6x7 55mm F4 Lens on 645D

    That's the auto/manual diaphragm switch. When the lens is mounted on a Pentax 67 camera, the default is for the lens to be set to "auto" to allow automatic diaphragm operation; the switch is moved to "manual" to stop down the lens for depth of field preview.

    This is similar to the way the Takumar lenses for classic Pentax screw-mount 35mm SLRs work. On those lenses, if you want to move the switch while the lens is off the camera, there's a tiny pin on the lens mounting surface that you need to press in. (Mounting the lens on a camera pushes the pin and enables the auto/manual switch to work.) Not the very obvious large pin that operates the diaphragm - there's a second one, much smaller, elsewhere on the lens mount. I don't have a P67 camera or lenses so I don't know whether they are exactly the same in that respect, but if you want to operate the switch while the lens is not mounted on a camera you might look for that extra pin. In any case, the auto/manual switch should work when the lens is mounted.

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