Hi, I am a newbie in DSLR. Recently purchased a canon DSLR and a canon fixed 50mm lens. When I try to shoot the street (the street will consist of below me using the 50mm lens f1.8 at night @ ISO 1600, I will get shutter speed of 1s. I am just wondering if I buy a tamron 200-500mm and aim at the street (so that the street will fill more of the frame), will I get a faster shutter speed? But I quite worried that the tamron @ its max zoom is f6.3.