Is worth getting the Canon EF-S 17-55mm f/2.8 IS USM lens if I already have the 18-135mm f/3.5-5.6 IS lens?
What equipment do I need for a wedding if I already have a Canon 60D, 50mm f1.8, 18-200mm f3.5-5.6 and a Neewer Tt560 speedlight?