Oly 50mm f/2 FT lens with adapter with OM-D E-M5 behaviour...?

Hi all,

I recently had the chance to use the Olympus 50mm f/2 FT lens on my E-M5 (with the adapter, of course), forcing myself to use that at my brother-in-law's wedding and manually focusing all the way.

Not something I'd care to repeat, by the way--but that wasn't what bothered me.

What bothered me was how the Live View or EVF doesn't seem to reflect any aperture change at all, effectively making any attempt to shoot with it guesswork. The DOF previewed was constantly f/2, even when the settings and the results were, say, f/4 or smaller!

Am I missing something here? Because I was sure the lens behaved properly on my mom's E-500.