Old Sigma Zoom-Master 35-70 question

[Diamond Dave]

A friend just gave me an old (1985) Sigma Zoom-Master 35-70mm OM mount lens. When I depress the depth of field preview button on the side, I can't see the aperture stop down inside the lens (I've set it at its minimum, f/22).

So the question is: is it broken? I don't want to waste time or film to find out.

Thanks.

 

[Diamond Dave]

Nobody?

 

[iolair]

What body are you using this on?

I use old Sigma lenses (not *that* old, mind) on a digital Canon, and they won't let me stop down the aperture at all - I'm stuck wide open. Could be that yours has the same issue.

 

[Diamond Dave]

On an Olympus OM-PC...but the lens won't stop down off the camera either. However, the Zuiko 50mm I have (OM mount obviously) will, just by depressing the DOF button, on or off the camera.