It's not just the weight of the camera that's important. You see, an 8x10 has a much bigger bellows than a 4x5, so you can force out a lot more pepper spray. There are a few tricks to it, however. You don't want to clip the corners of your groundglass, or the pepper will come out
towards you. You need to use a pinhole lensboard, and not a real lens, so the pepper will spray efficiently out the front. And of course, you
need to appeal to the bear's sense of vanity by asking him to pose right in front of the camera, where the spray will have the most impact.