The 70-200mm SSM is a hand-built lens in an age of machine-built lenses and is genuinely one of the best. > It's a pity it can't even track my dog running towards me on the Alpha 100, but that's a failing of an entry-> level camera body (it does fine on an older 7 film body).
Minolta film SLRs were renowned for their predictive autofocus, so
what happened when they went over to digital? - With much faster
processing shouldn't it work better? I'm just curious to try and
understand the reason for this.
If you go back to the days of predictive AF, you go back to single
central sensor operation (7000i and 8000i were the first models to
claim predictive AF, as well as the Riva 105i 'brick'). Once
multiple sensors and wide-area AF were introduced, the predictive
focus claims disappeared from Minolta promotional blurbs and were
not again used as a big selling point.
Have you seen any predictive focus claims for anything later than
the Dynax 7, or even for that?
As far as I can tell, they went for multiple focus points instead,
and the fastest focusing Dynax models - subjectively - were the
9xi, 600/700/800si and 7 for me. The 9 did not seem as fast. The si
series (above 500 level) had very powerful focus motors, like the
7xi and 9xi, probably because of the big lithium cell power.
Today's Min/Sony DSLRs seem to have less violent AF motors and less
tendency to propel the lens into focus in a single sudden movement.
There must be two dozens things they can improve on the A100 to
provide an ugrade which owners would buy into. A completely revised
AF module would be a good start.
David