I got myself the canon 550 back in May and have the 18-55 and 55-250 lenses. I take quite a lot photos at dogs shows etc and have found that im needed to swap the lenses quite a bit so thought I should look at getting another one. Im thinking of somthing with a range of around down at the 18mm end and up to 200mm ish but have no idea what is good. also im wondering if I should pay more attention to ones with lower F number as light at some shows can be quite poor. Should I look at the EF range as when I do get a new body I would probably got for a full frame one. Any ideas?