Hi Rod, I did own manual focus Sigma 24/2.8, which is supposed to be optically the same as it's AF version. I never noticed being it only 3.5 on any of my Pentaxes. In comparison to FA*24/2 which I have nowadays, Sigma is a bit sharper both in the centre and at the edges at infinity. At closer distances it seem that FA* starts to get the better one. Sigma is much more prone to flare than FA*. Also, vignetting can be a problem.
All in all, Sigma is a good lens, especially for the price. Hope it helps, Matjaz > G'day y'all. > > And? Have you? I know this lens is neat, but I've heard something > about that the effective aperture on a pentax mount is only 3.5? And > what about vignetting, really that bad? > > thanks, > > Rod. > > > >
