---- Graydon <[email protected]> wrote: > On Tue, May 19, 2009 at 09:06:05AM +0100, mike wilson scripsit: > > ---- Graydon <[email protected]> wrote: > > > On Mon, May 18, 2009 at 09:27:31AM +0100, mike wilson scripsit: > > > > If I was Pentax, I would have a switch, worked by the screwdriver, > > > > that turned the AF motor on/off, depending whether the driver was in > > > > or out of its hole. Maybe a halfturn anyway, to make sure that there > > > > was no slot to engage to. > > > > > > There are some edge cases -- like Tamron adaptall 2 adapters with a > > > non-auto-focus lens attached to them -- that would make this a rather > > > unfortunate default. > > > > Why? > > Because the screwdriver is there on the adapter, but there's nothing in > the lens to adjust. I don't want the camera body trying to turn > something it can't to find out if anything adjusts. > > And yes I could set the camera body to MF before mounting the lens, but > forgetting should not have dire mechanical consequences.
It doesn't. I use M series lenses all the time on my DL2, leaving AF on so that I can use focus confrim and trap focus. Been doing that for just over three years and for another mumblemumble years with my Z1-p. I cannot see any marks on my lens mounts at all. > > > > The other part of it is that the camera really, really needs to know > > > the focal length to auto-focus accurately. > > > > > > -- Graydon, who has tried to use focus confirm on the 500 while the > > > camera still thought it was 800. > > > > Not by my understanding of how AF systems work. Is there something > > different in the K10/20 systems? What they generally do need is a > > decent amount of light. > > I think it's connected to the shake reduction. > > So far as I can tell in the case of the K20D, autofocus and shake > reduction are really one combined system with different sensor inputs > and mechanical parts, but which meet up in the electronic controls. I don't see how the AF system would need to know the FL of a lens to work. It just measures contrast and stops everything when it is highest. -- 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.
