Pål Jensen wrote:
"Reason for this is that the heavy optics in a fast telezoom needs
improvement to the autofocus system, this probably means in-lens
autofocus motor, and it won't happen before the D replacement is ready
to go on sale."
This is clearly nonsense as Pentax already have fast zoom lenses and
primes with AF. As far as I know they work!
The collaboration with Samsung may have made Pentax able to finally
realease the KAF3 mount. The FA* lens replacements may be candidates
for USM. Then again it might not happen...
Pål
Pal, have you shot with a USM or AF-S lens? There's no comparison in AF
performance. USM absolutely blows screw-drive AF out of the water unless
you have either an ultra-light lens (like a 50mm) or one of the very few
cameras with a truly massive AF motor like the F5. I simply could not
believe the difference in AF performance between my old *istD and Tamron
28-75 f2.8 and the EOS 3 with a 28-105 f3.5-4.5 USM lens. The EOS was so
much faster I initially didn't believe my own eyes (Although some of
that likely has to do with having the same AF unit as the EOS-1D). USM
is needed in the Pentax line, badly.
I don't think the post you were responding to was talking about large
aperture zooms but rather fast AF zooms. Large aperture zooms have
bigger glass and are thus more difficult to drive for AF, on the other
hand, tehy do gather more light and usually have better contrast, which
helps the AF unit.
-Adam
- Re: new AF system soon (when D2 arrives)? Adam Maas
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