Canon 300mm zoom lens - what to get?

I have the 70-300L and used to own the non-L. I've never owned the 28-300, but I suspect that the 70-300L is quite a bit better, if only because it's a lot newer.

I don't know what camera you have, but this points out the better autofocus of the newer lens, especially if used with the newer 5DIII camera.

And of course, all other factors being equal, the bigger the zoom range, the lower the quality.

By the way, the 70-300 non-L is also excellent value for money, being considerably cheaper. Almost as sharp as the L, and very compact. Its little annoyances include a rotating front element and no full-time manual focusing.

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