I'm looking to buy a Vivitar 28-80mm f/3.5-5.6 Autofocus Zoom Lens for Canon EOS Autofocus Film & Digital SLR Cameras online. I was wondering is this a good lens for my Rebel XT Canon? I'm shooting a wedding soon. I doubt it will come in time, But i heard its a great on the go camera for just about everything. Please help thanks.