The lens cap for my OM 50/1.8 says "39mm" in it. I assumed this is the filter size, and also the size for the lens hood, but I have since read that 49mm is the correct size for the hood? I just want the cheapest hard or rubber hood I can find it for (only paid £20 for the lens itself!). Would this do the job: Heliopan LONG Metal Lens Hood 49mm : Teamwork Digital Ltd, Suppliers of Professional Digital and Large Format Photographic Equipment If so, does anyone know of anything cheaper? Paying the same for a lens hood as for the lens itself feels just wrong!