my son just made me a grandpa,a little girl.and i want to take some nice pictures of her.i have a canon xt.i want to get a 2.8 50mm lens a fast lens for in doors.my girlfrend as the xt to and she wants to take pics of young girls at the beach in the morning at the cape canaveral sea shore. would this lens be to fast for her to use at the beach in the morning? or should i get something a little slower like a 3.8 or what ever number they make 3- 4.8? or should i just by the 2.8 and she can stop down . what lens would be good for her. thanks for your replys.