Hi all! I am buying a Canon 600D soon with a default 18-55mm lens, and I would like to know what extra lens to get for farther pictures (100-200meters away)? I would be using it for plane spotting and taking pictures of airplanes at the Beijing Capital Airport. Some people recommended the 55-200mm lens, or the 70-200mm lens, and others have said you want one that goes up to 300mm. I am confused, and don't understand a lot of the f-values or what the mm do, so could you give me a recommendation? I want to spend about $100-200. Thanks