I took my D50 w/Quantaray 70-300 to an NBA game and they let me in no problem. However, after taking non-stop photos the entire warm-up and first quarter, I was tapped on the shoulder by security and asked to check the camera with them. Apparently it was deemed "professional" due to the length of the lens (and the Quantaray is fairly small when it comes to zooms). On the walk to check it in, I asked about it, and he told me that it was an NBA policy not to allow any lenses over 6". He said it was best to call before any event as each organization might have different rules. At least they had a secure are to check the camera (I removed the card before leaving it and left early to pick it up).