Ok i know very little about Olympus digital cameras and lenses however IF Olympus produces digi bodies with crop sensors that have the same OM lens mount as the 35mm film cameras, is it possible that you have a lens designed for a crop sensor and not full frame ( ie 35mm film) ?
That would cause it, but the M43 digital cameras have a different mount to the original OM film cameras. The mount diameter is much smaller.
Not unless it's a viewfinder with 100% coverage. Not many were. Most were 95% or less. I do know that some Nikons (F- pro models) had 100% coverage, but a lot of their other cams had like 92% only. So that would leave an outer margin unvisible in the 'finder.The vignetting would have been visible in the viewfinder so did that not ring alarm bells before pressing the shutter?
Not unless it's a viewfinder with 100% coverage. Not many were. Most were 95% or less. I do know that some Nikons (F- pro models) had 100% coverage, but a lot of their other cams had like 92% only. So that would leave an outer margin unvisible in the 'finder.