On Tue, 29 Nov 2005, Godfrey DiGiorgi wrote:
On Nov 29, 2005, at 6:38 AM, Fred wrote:
Does anyone have any opinions on the Sigma 28-105/2.8-4 ?
I'd like a faster autofocus 28-105 than the Pentax FA 28-105/3.2-4.5 or
either of the FA 28-105/4-5.6's (although the 28-105/3.2-4.5 is marginally
faster than the others). (This would be for use on an *ist DS.)
However, I'd be very skeptical of there being any substantive improvement
between it and the Pentax 28-105/3.2-4.5. If you want a better lens than
that, the Pentax 24-90/4 is the one I'd choose. Lens speed is generally not a
big factor in AF speed ... wide open contrast is a much greater factor. For
instance, the Pentax FA35/2 is a faster focuser than the FA50/1.4, because it
achieves better contrast wide-open despite being 1 stop slower.
I am not sure that's what he meant, I think he is looking for a faster
(aperture-wise) lens that is AF. The 24-90 is 3.5-4.5.
Fred, is the Tamron 28-75/2.8 too short for you? Don does not like its
bokeh, though.
Kostas
