Originally posted by gazonk You would still have (presumably) higher MP count. Granted, the new Canon 24-70/4 is almost exactly the same size as the Pentax 16-50 - but maybe it would be possible to make it quite a bit smaller if it doesn't have IS?
I doubt they could make it much smaller than a 16-50 that doesn't have VR either. When they say these f4 zooms are 'small', they mean 'small' compared to the f2.8 zooms.
Originally posted by Supernaut And it would fit perfectly on a cam that mounts nice FF primes
This ^^ nails the reason, I think. If you buy a FF camera and
only shoot f4 zooms, you don't gain much over shooting with f2.8 zooms on aps-c - but the f4 zooms are great
options to have along with other, more powerful lenses that give you the FF 'advantage'.
There are times when I go out with my aps-c Sigma 50-150 2.8 lens in DX mode on my D800, because I love that lens, it's smaller, and in many situations I don't need the additional speed. In DX mode, that lens is almost exactly a 70-200 f4 (really about 75-225 f4.5) and is about as big as the f4 70-200's are (and about as big as the 50-135 is.) It would be nice to have an f4 70-200 to take it's place so I can use all my MP, and can just swap out with a fast prime or zoom when I want the FF power.
But my main point was that I don't think it makes sense to come out with the f4 zooms
first, because it doesn't bring enough IQ difference from aps-c. Nikon's just getting around to the f4 zooms now. (not that Pentax has to do it just like Nikon.)
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