On Wed, 03 Mar 1999 Barry B. Bean wrote:
<snip>
>3) When the aperture ring is moved from 3.5 to 5.6 on the wide end
>(35mm), the aperture closes slightly. My other Zuiko zooms are fixed
>aperture, so of course don't do this, but my Sigma/Quantaray
>28-80/3.5-4.5 doesn't show this behavior. Did I get a defective
>lens, or is this normal behavior in a Zuiko variable aperture zoom?
>BBB
Hi Barry,
The 35-70 f3.5-4.5 was designed for cameras with spot metering (but
obviously can be used on all OMs). When you look at the aperture ring,
between 3.5 & 5.6 there is a white dot. This dot corresponds to f4.5 and
is the minimum setting use can confidently use with spot metering. The
lens will then automatically change the aperture to maintain f4.5
throughout the zooming range so you don't need to worry about exposure
errors.
This automatic 'stop down' feature is also why this lens is so hard to
focus when you have the aperture set at (or beyond) the white dot. It then
behaves as if it's a f4.5 lens! A 2-series screen is a must with this
lens.
Bill Rice
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