I've been out with it today with a different lens and a test roll. I'd had a play with it during the week using the bulb setting and the mirror slap seems to happen when the mirror falls and so the shutter will be closed by then. When I found it in an antique shop, I'd originally thought that the body was knackered but the lens appeared ok abd I wanted the lens to go on my OM1. It turns out that the body's ok and the lens is knackered. But an OM30, particulaely given it's battery requirements, fits awkwardly into my equipment plan. But it didn't cost a lot, so I'll probably donate it eventually and get an OM4 which is what I intended in the first place. Buying it was probably a mistake in retrospect.