B+W TOP-POL Linear Polarizer (58mm) lens mount_Olympus OM plus a pretty respectable f4

plus a pretty respectable f4 constant aperture

but excellent for fill and closer range low-light shooting

It looks like a rangefinder lens

It doesn't affect function at all

colour coded to avoid cross-contamination and designed to rest securely on the edge of a developing tray instead of just sliding in

B+W TOP-POL Linear Polarizer (58mm) lens mount_Olympus OM plus a pretty respectable f4B+W TOP POL Linear Polarizer for 58mm filter threads. A high quality polarizing filter to reduce glare and reflections. Note that a linear polarizer like this one may interfere with the autofocus system of a film or digital SLR. Image is for illustrative purposes only. Actual item may vary slightly.