Originally posted by MJKoski Screw drive belongs to screw driver, not hires digital camera.
Of course, you're entitled to your opinion (though I dread to learn what you think of manual focus lenses, given that).
I can't deny, I prefer more modern drive methods too, but screw drive works absolutely fine for me. Like I said, you have your opinion, and
that you're entitled to.
Originally posted by MJKoski It simply does not have enough accuracy for critical sharpness should some semi-intelligent logic some day provide useful AF. Why? The gears are sloppy as hell and have bad tolerances. For example 100mm WR macro does not hit exact same spot twice. Not even in LV.
Here, however, you are - with respect - plain wrong.
Every single one of my modern screw drive lenses - both for K-mount and Sony A-mount - has been calibrated for AF fine adjustment on multiple bodies using a SpyderLENSCAL. And every one of them - the DFA100/2.8 included - reliably achieves accurate focus at their fastest aperture settings, from starting positions at both minimum focus distance and infinity, using either PDAF or LV CDAF. If there's any focus inaccuracy, it ain't from the lenses. And with a dedicated focus test chart, the camera AF algorithms (which are already pretty intelligent) have no problem either... so I can only imagine you're basing your claims on less controlled testing.
Actually, most of my older screw drive lenses - like my copy of the FA50/1.4 and Minolta AF 50/1.4 - are just as reliable and accurate as the newer ones. I do have an old Pentax F28-80 with
vicious torque, and that occasionally overshoots very slightly - but not very often. It's an exception compared to the rest of my fairly extensive lens collection.
If your lenses are "sloppy as hell and have bad tolerances", maybe they need servicing. Or maybe there's a specific or specialist photographic activity you haven't mentioned, where you might have the ghost of a point re screw drive accuracy. If so, it certainly doesn't affect general day-to-day photography, based on my own experience.
I'd respectfully suggest you don't make blanket statements and draw hasty conclusions based purely on your own lens copies and photographic activities (as with the Irix lens we previously discussed). Whilst your intentions may be noble enough, it risks spreading inaccurate information to the wider audience.