My next purchase consists of a lens, polarizing filter for all lenses, a flash, and a sync cable (?) for the flash so I can use it off camera... Here is everything I am purchasing... Can someone please confirm that this is everything I should need for all things to work? --Hoya 58mm Circular Polarizer Multi Coated Glass Filter (Adorama) --Sigma 70-300mm f/4-5.6 APO DG Macro Tele Zoom Lens for Canon EOS Cameras (Adorama) --Bower Dedicated Dual Intelligent Digital Flash / Ring Light Combo for Canon EOS Cameras (Adorama) --Precision Design E-TTL Off-Camera Flash Cord for Canon Digital SLR Cameras (Amazon) --Adorama Step-Down Adapter Ring 58mm Lens to 52mm Filter Size (Amazon - it's only $1.99 vs. $6.95 on Adorama) Is this everything I should need for the flash and to make this polarizing filter fit on all my lenses including the sigma lens listed? All 3 lenses that I will have are going to be either 52 or 58mm diameters.