On Mar 27, 2005, at 8:46 PM, Boris Liberman wrote:
... Then, why on Earth, Pentax reduced manual focus confirmation only to the center most AF sensor? ...
Yes, the focusing mount is driven by the servo or the hand. Either there is more information passed from lens to camera when in AF mode which enables the SAFOX system to make discriminations on its 11 point focus matrix *or* multipoint focusing for manual focus confirmation was simply deemed not to be particularly useful. I know I don't look at the focus confirmation light, and often turn off the focus point illuminator when using manual focus lenses, as I find focusing on a matte fresnel field to be more accurate and comfortable.
I suspect Pentax hasn't produced a screen with split image rangefinder focus assistance for the *ist D/DS due to the same reason that the aftermarket supplier (tekade.de?) warn users: spot readings will be inconsistent because the spot metering sensor is not exactly aligned with the optical axis of the lens, and issues of exit pupil/alignment of the prisms/etc affect the readings.
I know others love these focusing screens, but I always replaced them with plain matte fresnel screens on my SLRs in the past. The prism rangefinder aids are not accurate for critical focus although they're useful for getting focus into the ballpark quickly with short focal length lenses.
Godfrey
