We are new to DSR, having previously used a digital compact - I have experimented a little bit with aperture and shutter priority on the compact. We are travelling to Canada at the end of October, visiting Toronto, Niagara and Churchill to see the polar bears and want to buy a telephoto lens particularly for the wildlife bit. I imagine the 18-55mm lens we already have would be better for the cityscape, so would a Tamron Zoom Wide Angle-Telephoto AF 28-300mm f/3.5-6.3 XR Di LD Aspherical IF Macro Autofocus be the right lens to buy? (we don't want to spend a fortune). I am a bit concerned about the aperture range. Would a 3.5 or smaller aperature be okay for wildlife or should we be looking for a lens with a larger aperture?