We talk a lot about specific crew positions at times, but if you're just starting out, it's hard to get a sense of what many of these people do unless you can see them in action. Thanks to Evan Luzi at The Black and Blue, you can check out this video he posted showing the major departments and some of their crew positions. These positions can vary slightly depending on the country you're in, but for the most part, this is what you'll encounter on pretty much any organized set.
Video is no longer available: www.youtube.com/watch?feature=player_embedded&v=Vg22IhSNWSQ
I think there are a lot of positions that filmmakers try to do themselves to save money, but in my experience, the Assistant Director and the Unit Production Manager/Line Producer are the ones where it really helps to have experienced people. If you're working in low budget, I've found that having these people can really help you think on your feet and move quickly. Often with low budget it's a race against time to get everything shot in the short time allotted, but with experienced people at these specific positions, you might have a better chance of getting everything you need done on time and on budget.
As I always say, if you haven't checked out Evan's site before, it is absolutely a gold mine for information related to being a camera assistant, as well as little nuggets like this that he finds every once in a while.
[via The Black and Blue]