Photographing Niagara Falls Advise

Here are a few shots from Niagara falls. Nice attraction but very crowded when I was there last week.The fireworks shots were taken through a tinted window. All taken with Canon 7D and 17-40 except the maid of the Mist pictures which were taken with an olympus waterproof camera. In the end I picked up a Tiffen .9 ND but only used it a couple of times.