What features are a MUST when buying a digital SLR camera for a beginner? (budget is up to 600.00, maybe 650.00 with shipping included) What features can I pass on if necessary? Do any particular brands have additonal lenses that cost much more than for other brands? Any that are likely to be a better price? What about ISO , what should I look for and can someone please explain ISO to me? What about buying used? Good idea or not? Finally, what items do you usually need for your new camera, but that are not usually included with your kit?