I bought a Porta Brace Rain Slicker for my Canon XL-H1. Not going to shoot in downpours, but if there's a drizzle I'll go ahead.

My question is about protecting the lens itself, which remains exposed to the elements. Is the only option to make sure the lens is always pointed down? Would a lens filter add any protection from water?

I've filmed for very long periods during serious rainstorms, and normally all that is needed is a decent rain cover plus a UV filter over the front of the lens.

The Porta Brace raincover should be able to withstand plenty of monsoon weather with no problems (I used to use the Kata CRC-11, but for the past year have been using a different warterproof cover designed by a company in UK). I also have a small waterproof cover with velcrose attachments that fits to the front of the lens for when I'm forced to leave the camera out in the rain between shoots.