On Wed, 27 Sep 2006 17:48:34 +0200, Adam Maas <[EMAIL PROTECTED]> wrote:
> Lucas Rijnders wrote: >> Op Wed, 27 Sep 2006 16:07:19 +0200 schreef Adam Maas >> <[EMAIL PROTECTED]>: >> >>> Lucas Rijnders wrote: >> >>>> Anything on backward/forward compatibility of the USM and the old AF >>>> system? Did your rep explain the AF/MF switch on the lenses? >> >>> The AF/MF switch on the lens will work just like it does on Canon USM >>> or >>> Nikon AF-S lenses. It's not exactly unique. Does exactly what it looks >>> like it will do (Allows you to turn off AF on the lens). >> >> I am not familiar with Canon or Nikon lenses. Could you explain what the >> point is, given that you can turn off AF in the body, and that USM (at >> least the Canon variant) allows manual focus in AF mode? >> >> Genuinly interested, > > Note that not all USM lenses allow full-time manual focusing. > Micro-motor USM lenses (all low-end Canon USM lenses as well as the > Nikkor 18-55 and 55-200) do not allow it, except for the 50 f1.4 USM > which is clutched like a DA lens (the 50 is only micro-motor USM for > size reasons, ring-type would make it notably bigger). I would not expect this solution with Pentax: they have good old in body AF for budget lenses... > The switch on the lens disengages AF in the lens directly, and tells the > body that it's been done (ensuring nothing bad happens to the motor). > It's also much more conveniently located than the on-body switch Depends on what You're used to, I think. On the one EF lens I used (a consumer 28-80, and I used it very briefly) I did not find the location that handy... > typically. Note that while USM allows MF override, in AF-S mode it works > just like the clutched DA/D-FA lenses, you need to let it lock first > then override. That's a point. We'll see how it is implemented: two AF/MF switches can potentially be great fun for the helpdesk (will it be an AND or an OR situation?) Thanks for the explanation. -- Regards, Lucas -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
