Hi,
I took a shot last night with the speed dial set to 4 on my FM2n.
Am I right in thinking that the shutter should have stayed open for four seconds?
The FM2n shutter speed dial does not have any speed longer than 1 second. 4 is actually 1/4th sec. To open the shutter for 4 seconds, you must use B(ulb) and hold the shutter button for the 4 seconds.