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Thread: Mamiya 645 Pro 50mm f/4 Shift

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    Member DanTidswell's Avatar
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    Mamiya 645 Pro 50mm f/4 Shift

    I'm certain that this is a stupid question, but can someone tell me what this rotating part of the lens does?



    I did look for a manual before asking - honest! :-)

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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: Mamiya 645 Pro 50mm f/4 Shift

    It is the lens tab that connects to the exposure coupling pin on a Mamiya 645 Pro. Basically it is used on the older non-electronic coupled cameras to tell the body the f/stop selected on the lens.

    Quote Originally Posted by DanTidswell View Post
    I did look for a manual before asking - honest! :-)
    Try page 10 here: http://www.cameramanuals.org/mamiya_...ya_645_pro.pdf
    Remember: adventure before dementia!

    As Oscar Wilde said, "my tastes are simple, I only like the best"
    Likes 2 Member(s) liked this post

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    Member DanTidswell's Avatar
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    Re: Mamiya 645 Pro 50mm f/4 Shift

    Thanks Graham, I would never have figured that out on my own, that website is a wonderful resource.

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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: Mamiya 645 Pro 50mm f/4 Shift

    It's an absolute gold mine if you have an older camera! I use it all the time.
    Remember: adventure before dementia!

    As Oscar Wilde said, "my tastes are simple, I only like the best"

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    Senior Member ondebanks's Avatar
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    Re: Mamiya 645 Pro 50mm f/4 Shift

    Quote Originally Posted by GrahamWelland View Post
    Basically it is used on the older non-electronic coupled cameras to tell the body the f/stop selected on the lens.
    Sort of...more precisely, it tells the metering prism the f/stop *difference* between full aperture and the stop set on the lens for shooting. It is a relative aperture indicator, not an absolute one. For example, mount an 80/1.9 lens and set it to f/5.6; note the position of that coupling lug. Then mount a 300/5.6 lens and set it to f/11; the coupling lug rotates to the same position, as in both cases there's a difference of 2 stops.

    I think the system is rather clever in its simplicity. It tells the meter what it needs to know for correct exposure; no more, no less. Feeding in an absolute aperture value would allow back-calculating of the light eV level, but would not result in a different exposure.

    Ray

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    Member DanTidswell's Avatar
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    Re: Mamiya 645 Pro 50mm f/4 Shift

    That is quite elegant Ray

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    Re: Mamiya 645 Pro 50mm f/4 Shift

    The system was developed after the old Nikon systems of the 1960's which also sported this claw type connector on the lens.
    Rod
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