Shooting at a farmer's market
A friend of mine whose family runs an organic farm has asked me to go with her to shoot some photos of a farmer's market. The company that runs this farmer's market wants to use the photos on their web site, and they would like photos of people enjoying the market -- they're not looking for photos of the vendors, or the merchandise, but of kids having their faces painted or people looking at the produce, etc.
My question is: When people are out in public in a shopping situation like this, how do you handle this type of photography? Do you always need to request their permission to take a shot (which sometimes will mean that you lose the more natural 'moment'?!) and/or do you need them to sign releases allowing the pictures to be used on the web site? I know there's some law that suggests that if people are out in public places, they have no reasonable expectation of privacy and what not... otherwise, street photographers wouldn't be able to publish much. Having said that, I remember in Bryan Peterson's book "Understanding Exposure", he said he always gets people to sign releases when he takes pictures of them in public places.