how much stops an IS lense affect, compare a normal lense?
Ex. if I shot with the 50mm, my secure shut has to be at least 1/80 (50x1.6=80 and we talking about my new 450d, APS), what with a 50mm IS?
I bought a 55-250 IS, sure better than my old 75-300 II and it would cover the 60, 65, 70mm that sometimes I miss out...and...what do you think about that lense? its 55-250 IS 1:4-5.6?