Analog film photography and cameras

Yup. What I was thinking of is how it would work with meter correctly with auto stopdown if it doesn't have the OM-system biasing lever? I'll find out soon enough since I've bought it now (forgot to ask the guy about the details). Anyway, if I have to use it in manual it's not a big deal.

Do you mean that genuine OM lenses stay wide open while you meter, focus and compose and only stop down when you actually fire the shutter?

I would have thought that would have been taken into consideration by the 3rd party lens manufacturer and that the lens would have what it needed to do this. Either that or the aperture will stop down as you move the ring, should still meter for aperture priority ok but the finder will darken as you stop the lens down.