Open container citation in San Francisco?

I was walking in the Tenderloin with 2 friends on Thursday and we had open beers in brown paper bags. 2 cops stopped us and they claim it was to tell my friend to put her camera away due to the bad nature of the neighborhood but then they made us take our beers out of the bags and gave us citations. We think it was because we looked like tourists and being that the state is in the shitter, they assumed they could get money from us. I gather that it is illegal to drink in public even if you cannot see the container, although I thought it was okay. It’s bullshit. We weren’t even drunk and had JUST opened the beers a block away. Is this a violation of our rights?

Does anyone know how much an open container citation fine costs? Is it worth it to show up at court and fight it? Does the whole “if the officer doesn’t show, the citation is thrown out” rule apply for this? Also, my friend was visiting from NY – what happens if she doesn’t pay the fine (they have her ID information and that she was staying at my residence, but can’t she easily claim someone stole her ID?) ? I’ve done some research but would like your opinions because you guys always come through :)