Weather Proofing On 300 f4?

My 300 f44 IS got a soaking in Saturday, and now it seems to be hunting for focus. This is with or without IS, all distance ranges, and all focusing modes on my 400D. Does anyone know exactly how weather proof this lens is?

The 300L-F4 is weathersealed, but your 400D is not.
Have you tested the body with another lens?

Weathersealing, from what I've read, is effective if the lens is mounted on a weathersealed (read: 1 Series) body and has a filter on the end of it.

the 300 f4 is NOT weather sealed.

DavidEB wrote in post #2473882
the 300 f4 is NOT weather sealed.

DavidEB is correct, that is only my 5th mistake this year

Thanks guys. The body was pretty much coveed by the hood on my jacket, but the lens got a good soaking. I've tried another lens, and that was fine, so it looks like I could have a problem.

For future reference, the "Weather Sealed Lens List."

https://photography-on-the.net …08338&highlight​=weather+L

When clients would call and say "i forgot to take off my watch..." I would tell them to open the crown and heat the watch with a hair dryer. You might give that a try.

WARNING: DO NOT USE A HEATGUN!!!

It's currently in the airing cupboard, drying out, so hopefully it will be o.k. for next Saturday..

DavidEB wrote in post #2473882
the 300 f4 is NOT weather sealed.

They are all "weather sealed"... or not.....which entirely depends on the definition of "weather sealing" that one uses.

Some people thing "submersible down to 4 ft", some people think "drip proof". Unless we have a bona fide technical standard to which that "weather resistance" conforms, we are just stumbling in the darkness of Canon's trickery and laity views.

The hair dryer works faster, thus, preventing rust. Having never seen the inside of a 300L, I do not know if there are any components that will rust.

So the next question is, can anyone recommend a good DSLR rain hood? Preferably big/long enough to cover the 300.