I got one of the eBay (HeavyStar) hoods for my Canon 50/0.95. It takes a 72mm. Got one from them and I'm very impressed at this US$7.95 hood. This is a very good deal considering collectors are now paying 450+ for the original Canon hood.
I think Guy had said how nice these were and I concur.
I like the fact it's screw in. Just put the IR cut filter on screw the hood on and forget it. Do need to figure out a cap for this 72mm monster but it has a 77mm OD. So, I should be able to find one or make one.