On Feb 24, 2010, at 2:02 PM, William Robb wrote: > > ----- Original Message ----- From: "Bob Sullivan" > Subject: Re: On FF but without intent to start a flame > > >> Yes, that's pretty sad. Is it mechanical or electronics that are >> failing? It would seem that the lens would have plenty of travel to >> sort things out mechanically. Is it weak electronics? >> I get better results with the DA60-250/4 at the short end with >> autofocus wide open than with most other older autofocus lenses >> (FA's). > > I think it's just that the AF sensor isn't accurately able to pick out what > it is pointed at. The sensor points may be too large, or the resolution of > the AF driver may not be fine enough. Unfortunately, the AF misses on a > pretty random basis, sometimes slightly behind, sometimes slightly in front > and somtimes, albeit disturbingly rarely, bang on the money. > It's too bad because when it works, it works very well indeed, it just > doesn't work often enough. > Are you using selective autofocus? I use a single point for focus exclusively. When shooting model, it goes on the eye of course. I haven't had any problem getting good focus with the DA* 60-250 or the FA 50/1.4. Paul
> William Robb > > > >> On Wed, Feb 24, 2010 at 9:49 AM, William Robb <[email protected]> wrote: >>> The shoot I did on Saturday had about 50% missed focus shots, and this was >>> with the lens well stopped down. >>> I don't even try to use AF with that lens above f/2.8 because I won't have >>> anything usable. > > > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
