All the three last choices seem to mean the same (never shoot wide open).
I have two f2.8 zooms, 17-55f2.8 IS and 70-200f2.8L IS and don\'t hesitate to use them wide open when the need arises. However, if I have just a bit more light, I stop them to f3.2 to f4 to get a bit sharper results. Also, quite as often I stop them to get some more depth of field. So, which alternative should I vote?
Like f4 zooms, also f2.8 zooms improve in sharpness when stopping down. But they do it one stop earlier. In fact, my 17-55f2.8 is mostly shaper than my 24-104f4L IS, both lenses wide open. With some focal lengths the corners might be sharper with the 24-105 at f4 than with the 17-55 at f2.8.
I don\'t have the 70-200f4L IS so I cannot compare my 70-200f2.8L IS with it. But what I\'ve seen reviews and samples, the f4L IS is very sharp, so the situation there might be a bit different, especially at 200mm which is the weak point of the f2.8L IS.
Finally, don\'t generalize like \"f2.8 zooms\" because they are all different. And it also depends on what you compare them with. Basically f2.8 zooms can do all that f4 zooms can - but they can also shoot at f2.8 to f3.5.
Jan 04, 2009 at 02:43 AM
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