I don't know the Sigma lens in question at all. I no longer even look
at Sigma products, however, having been burned too frequently in the
past by them.
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.
Godfrey
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'm afraid of:
1. softness
2. flimsiness
3. bad bokeh
I know very little about Sigma lenses (except for some generalities
that
may or may not apply to this particular lens). Any opinions? Thanks.
[Gee - I really wish that Tamron made the 28-105/2.8 in Pentax mount.]
