70-200 f4: replacement for f2.8 or addition?
Agree, 2.8 is 2.8 as another poster said. Though the 300 F4 is in many a sports photographer's bag and I suspect the 70-299 F4 will be too.
Not all operate in big arenas where the separation of 2.8 is all but mandatory.
I really doubt many 300 f/2.8 owners bought it for the additional DOF primarily. With me is was that it can operate in half the light of the f/4 model. Moreover, it can handle converters in dimmer light which really makes a difference.
Prior the the new f/8 sensors, there was an issue trying to AF at higher than f/5.6. The 300 f/4 then was mostly limited to a 1.4 converter while the 300 f/2.8 could use any converter. Double the light and converter use got the big bucks out of me; not DOF.
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