Originally posted by kiwi_jono I have only just got around to reading this post and its a very good guide.
Only thing I would like to chime in with, although technically not the camera /lens, is care also needs to be taken with your camera bag / pack, in that...
1. Different bags have differing amounts of weather resistance. Don't assume that if it comes with a rain hood its 100% weather proof. Good brands with "All weather" rating are a good start.
2. Hopefully fairly obvious but if it starts to rain and your bag has a rain hood - do use it as most bags will seep water after a time without it. Also the hood needs to be fully wrapped around the pack.
3. Don't put you bag down on very wet surfaces (and definitely not standing water). Even "all weather" bags will leak through their bases if put in standing water. For packs same goes for lying it straps down in water.
4. If there is strong possibility of walking in a lot of rain, consider put your gear in water tight bags within your camera bag / pack.
5. After being in the rain (especially for extended periods) make sure you take all your gear out and check it for moisture. Then open bag up and put in a warm and dry place. Worst thing to do is put a damp bag away with gear still in it.
6. Obviously opening the bag in rain is to be avoided - unless you are under some good shelter.
I have once ended up damp finding its way into a pack during a walk in fairly heavy rain. The pack had a rain hood which was in place. The moisture got in because the rain ran down the back of my rain coat (and jacket hood) and down the back of the pack (which is not covered by the hood). My camera gear was fine but I put it in a warm dry place to ensure it was completely dry (separate to where I put the damp pack of course). It was not a particularly good pack at the time (forget the brand) and probably other packs will handle this better but if I got caught in heavy rain again I would certainly check the back of the pack and consider using a poncho over self and pack.
Yes, this is great advice.
The only mobile equipment storage I completely trust in wet weather is my waterproof hard cases. I've been on a few boat trips where one of my cases got very wet from both rain and spray, and upon opening it at my destination there had been - as expected - absolutely zero ingress of water. Allegedly, they'll even withstand complete submersion for a certain amount of time, though that's something I hope never to test. But, of course, they're no use for carrying gear on a shoot - they're strictly for getting it to and from a location. Beyond that, I find my Kata bag's rain cover does a good job in keeping most of the bag dry, though I wouldn't want to be carrying it in heavy rain for long, for the reasons you mention.
I don't think anyone's mentioned the "type" of rain (for want of a better word) yet, so I'll raise it. Big, heavy rain-drops should make anyone think carefully about their gear and bags, but very fine drizzle can be equally drenching without the photographer noticing it. Years ago, when visiting the island of Lundy off the coast of Devon, I went out for a long walk with my camera and fitted lens, stored in a small Tamrac shoulder bag. It wasn't even raining, as such - rather, it was misty and there was an incredibly light drizzle... a "fret", really. By the time I got to my first location for taking shots, my Tamrac bag was so wet that I didn't use it for the rest of my walk. Plus, I found I had to wipe my camera and lens down almost as often as I would in heavier rain, as the standing water built up really quickly around controls, buttons, the viewfinder, lens mount etc...