I am going to buy a Canon DSLR (T2i or T3i) with a Sigma 30mm or 50mm f/1.4 lens for clear, low light train shots. I am also planning to get a telephoto for outdoor train shots. I have narrowed it down to the Canon 70-200mm f/4L USM and the Canon 200mm f/2.8L. Both lenses, according to reviews, are great buys. However, I want to know which of the two lens are perfect for me. Please note that I will have the money to buy either of the two.
http://www.bhphotovideo.com/c/product/183198-USA/Canon_2578A002_EF_70_200mm_f_4L_USM.html#pr-header-183198
http://www.bhphotovideo.com/c/product/129190-USA/Canon_2529A004AA_Telephoto_EF_200mm_f_2_8L.html#pr-header-129190