There is a certain etiquette my foodie friends and I observe when dining out. We don't touch the food until the photographers in the group have taken pictures of it.
Very rarely does this take more than a minute, because although they like to document their dining experiences (and some of them blog about it), most of my friends are aware that the food is there to be eaten, not simply pictured.
Not everyone seems to have this awareness, though. At many restaurants, I have watched in bemusement as foodies (who I don't know) at nearby tables pull out their cameras and take photos of every dish from every possible angle. Upon being shown to their table, they choose where they want to sit not because it has the best view of the rest of the room, but because that particular seat has the best lighting for their food photographs.
Chefs are usually of two minds when it comes to diners photographing their fare. On one hand, it is flattering that people are so interested in their food that they want to show what they ate to their friends - and if it is done by a blogger, it can be good publicity. But if the photographer takes too long in getting the right shot, the quality of the food can suffer because it isn't being eaten at its optimal temperature. Sauces dry out on hot plates, herbs and other leafy garnishes can wilt, things that should be crunchy become soggy, cold ingredients melt or become warm, while hot ingredients become tepid.
If you do photograph dishes at restaurants, be considerate to other diners, especially the other people at your table (who, if they're polite, won't start eating until you finish your impromptu photo shoots).
Check your camera settings, including white balance, before the food starts arriving so that when a dish is served, you can photograph it as quickly as possible. Don't intrude on other diners: turn off the flash, please! And stay put: take the photos at your table, don't move the food to a nearby window ledge, even if the lighting is better there.
Most importantly, if the restaurant has a policy of not allowing photographs, then put the camera away, sit back and just enjoy the meal.
Truc (tryk): noun, masculine, trick, gimmick, device. A French word for a chef's secret.