>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!
: Jan Steinman <mailto:jans@xxxxxxxxxxx>
: 19280 Rydman Court, West Linn, OR 97068-1331 USA
: +1.503.635.3229
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