It's Sunday, I'm in San Francisco the day before the work starts and I'm out taking pictures with one eye on the fog and one on Flickr. It's all very well being part of a vibrant, experimentally minded and consistently challenging online digital image community — every journey is spiced with the expectation that you'll come across something unusual enough to make the hungry eyeballs take notice. But Flickr seems to have a very strong San Francisco-London axis, so the chances of finding an image that hasn't been done to death are slim. That's mildly discouraging.
Yet the magic of the viewfinder soon takes over and I forget all such reservations. I'm blasting away at stray rubbish blowing ironically in the wind, grumpy tramps, perspiring cyclists and random architecture. As I'm doing something vaguely arty with reflections in a large glassy building, I get approached by an elderly gentleman in a uniform.
"Sir? Sir? You can't take pictures of that"
I have been guilty in the past of picturing that which should not be pictured. A fascination with radio antennae got me into trouble in Morocco, while I have been warned by police on Hampstead Heath not to take pictures of a funfair because there were children present — I've still not come to terms with being a member of a culture that thinks that way. But a bog-standard building on one of San Francisco's busiest roads?
"The owners forbid it, so I'm going to have to ask you to leave"
I look at the pavement on which I stand. To where, I wonder, am I supposed to leave?
"This is a public place, isn't it? How can you ask me to leave a sidewalk?"
Security guards are often asked to defend the indefensible, so I'm not too surprised when he executes a neat non-sequitur.
"You can take pictures of any other building here, but not this one. The owners don't allow it." "I can't see how they can prevent it. I'm not breaking any laws, am I?"
In response, he points up at the building. "There are a lot of cameras in that building taking pictures of you", he says.
"Good!" I say, not precisely truthfully. "Then it's a fair exchange, isn't it?"
"It's not allowed," he repeats. "Please stop now."
"I don't understand," I say. "What law am I breaking? If the building's on a public road, why can't I take a picture of it?"
"If I was in England," he says, "there'd be rules I didn't understand."
There are times to stand one's ground and times to bid farewell: having an aversion to causing trouble in a foreign country, I elect to make a tactical retreat.. It's not that great a building. For anyone else who fancies a pop, it's 333 Market Street, San Francisco — and if you're not sure you'll recognise it, any half-decent search engine will throw up plenty of pictures. Google Earth has a particularly good one — but I'm sure you're not allowed to do a screen capture.