I have a Canon 5D Mark ii. I have a 70-200 f/2.8 lens. I could get the shutter speed but not the zoom. I guess I'd have to get a bit close. Maybe I'll ask for the 300 for my birthday. I do have a 2X converter for my 70-200 but I will lose 2 f-stops. It should still work, don't you think? At 1600 ISO do you get a lot of noise when printing? How big can you print without distortion?