Surly Pentax could implement this in the body though? Have a 'superAF mode' which only engages AF when the shutter is depressed and once focus lock is achieved, retracts the AF gear back into the body. Should be simple.
> -----Original Message----- > From: Christopher Lillja [mailto:[EMAIL PROTECTED]] > Sent: 20 November 2002 18:31 > To: [EMAIL PROTECTED] > Subject: Re: Was: ...lenses from Sigma! Now: advantages of HSM > > > IMHO- The real advantage of HSM (at least in the Canon and Nikon > implementation) is "Full Time Manual Focussing," allowing one > to touch up the fine focus after lock has been achieved > without touching any switches, levers, grinding of gears, > etc.... this is no small thing, after you've experienced it... > > Chris L. > > Date: Wed, 20 Nov 2002 08:56:20 -0600 > From: "Ryan K. Brooks" <[EMAIL PROTECTED]> > To: [EMAIL PROTECTED] > Subject: Re: New 100-300/4 and 28-70/2.8 lenses from Sigma! > Message-ID: <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=us-ascii; format=flowed > Content-Transfer-Encoding: 7bit > > Len Paris wrote: > >>It seems that apart from marketing blah blah, the only > >>advantage of USM is its quietness... > >> > >> > >>-- > >>Best Regards > >>Sylwek > > > > > > I think, maybe, there could be some mechanical efficiency gained by > > putting the focusing motor in the lens itself rather than in the > camera > > body. It could lead to slightly faster, as well as quieter, > focusing. > I > > would need to buy a few more USM/HSM lenses to be able to say for > sure, > > though. > > > > Well, it (USM) certainly seems to allow you to have AF in > lenses that we > don't. > > R > >
