Hi - some advice please. I'm using a Canon 50D with an 18-200mm kit lens, which I'm enjoying thoroughly. It covers a great range from wide-angle through to telephoto and I'm very happy with it. I want to pick up a fast prime for indoor use - mainly parties and low light situations. It would be used for single portraits and 'unaware' group shots - you know the kind of thing, trying to get as many people in the room in a photo from the corner. I've read plenty of reviews on the Canon 50mm 1.4, Canon 50mm 1.8, Sigma 50mm 1.4 and Sigma 30mm 1.4. I don't have the budget to stretch to the Canon 1.2 range. I've been out of photography for a long time and in the past would have went for a 50mm without too much thought, but with the 1.6 crop the 30mm seems a good alternative. So please, some advice. On a crop - in those low light situations, the 50mm or the 30mm? Furthermore Sigma or Canon? I know there's been similar questions in the past and I've read a lot of threads, but I'm really looking for some specific advice. Thanks.