I am looking to purchase my first SLR digital camera but I am very confused. I currently own a Fuji S5500 which has a built-in lens that has a 10x optical zoom. I understand that with an SLR camera the type of lens you add determines the type of photographs you can take. How do I calculate what magnification a certain lens would take? I would like to have at least 10x zoom with my new camera set-up. For instance what zoom does a Canon EOS 400D with an 18-55mm (standard) lens give? How about a Nikon D40X with 18-55mm lens? I don't want suggestions on what camera to buy just how to determine what the magnification would be with a certain lens. I hope this all makes sense!