On Tue, May 19, 2009 at 04:16:17PM +0100, mike wilson scripsit: > ---- Graydon <o...@uniserve.com> wrote: [gunch] > > 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.
With the Adaptall 2 adaptor, there's a lens, and then a mount-specific adaptor. If the lens is pure MF, and the adaptor -- because that's what one can get off ebay -- supports auto-focus, the camera has absolutely no way to tell that the screw drive isn't connected to anything. That's the unusual edge case. I don't imagine the problem would arise with a Pentax M lens. > > > > 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. AF doesn't, but the shake reduction does, and the autofocus and the shake reduction talk to each other. I don't know why, or how; I do know the K20D firmware upgrade that was supposed to improve anti-shake increased autofocus speed. -- Graydon -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
