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Message: <blockquote data-quote="mtyoung400" data-source="post: 1678969" data-attributes="member: 66935">G'day everyone,I'm currently looking at purchasing either a 100-400mm f4.5 L IS, or a 300mm L IS f4.5. At the moment I'm leaning towards the 100-400mm as I;ve heard a lot of good stuff about this lense, as well as seeing what other people's photo's are like with it.Something that Roy posted is a very relevenent comment, and one I'm trying to find out more info on; Does the 100-400 produce softer images when opened right up? My current 70-300mm does this and it's one issue I dont want to have in a new lense. If it does then getting the sharper 300mm would be better. The addition of a 1.4tc would make it a f4.5 lense with 420mm reach, but would that produce a sharper image than the 100-400mm opened wide up?</blockquote>