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Re: [OM] Meter readings with 600mm telephoto

Subject: Re: [OM] Meter readings with 600mm telephoto
From: "John Petrush" <petrush@xxxxxxxxxxxxx>
Date: Tue, 24 Nov 1998 20:49:01 -0800
This got me to looking at my T-mount adapters (I have several for various
tele- and micro- scope attachments.  On mine, there are three equally spaced
screws that, when loosened, allow the outer ring to rotate about the inner
mount.  If others have this same type of construction, would it not then be
possible to "tune" the rotation orientation to meter correctly?  Just a
thought........

John P
______________________________________
there is no "never" - just long periods of "not yet".
there is no "always" - just long periods of "so far"

>>From: "C. Hertzler" <hertzler@xxxxxxxxxx>
>>
>>Jan Steinman <jans@xxxxxxxxxxx> wrote:
>>
>>>If it is a T-mount lens, then all bets are off for proper metering,
>>>because the T-mount manufacuturer has no idea about the speed of the
>>>lens it will be mounted on.
>>
>>That is not necessary. The lens gives only a relative aperture
>>information to the camera. In an automatic lens, it tells the
>>camera: "I am open", or "I am set to x stops below open". In a T
>>mount lens, it is always  in the open position...
>
>I beg to differ. I have a T-mount that is right on, and another that is two
>stops off. I can swap them on the same lens and see the difference on the
>meter, and I can measure the position of the coupling pin and detect a
>difference.
>
>>It doesn't make a
>>difference, which absolute value it is.
>
>Perhaps I wasn't clear. If the T-mount is saying "I am set to x stops below
>open," then of course it makes a difference! I SUSPECT many cheap T-mounts
>aren't too precise in the positioning of this coupling pin, but I KNOW at
>least one is off!




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