In article <[EMAIL PROTECTED]>, [EMAIL PROTECTED] (Christian Skofteland) wrote:
> Get F, FA or A lenses... Argh, more money. Being a maximum aperture fanatic - because my sight isn't too great - that looks like a 24/2.0 to model a 35/2.0 on 35mm. But to model an 85/1.4 or 85/1.8, I seem to have a problem. The focal length I need is 60mm. Either use a 55mm SMC Takumar in stop-down metering mode, or use a 50mm F, FA or A (a little too wide) or a 77mm (a bit too narrow). Looking at my sole A* lens, I see there's an electrical contact, which looks as if it will match up with the ones on the *istD lens flange, so that gives me a 135-equivalent. At f1.4, heh, heh! > You can use screw-mount lenses in stop-down manual metering. You will > not get "open-aperture metering" (except when you want to shoot wide > open). OK. Is the adaptor needed to do this a standard M42-on-K adaptor, or is there more to it than that? > With Ks and Ms you get nothing. No metering at all so you will have > to use a hand-held meter or guess. some have suggested adjusting to > ISO settings to use these lenses but I have no idea what they mean. Rats. From memories of the earlier discussions, and a look at the catalogue photo of the *istD, it would seem: The *istD has the aperture release cam, so that it can tell a lens how far to stop down when that's been set on the body, or release a lens without a control-by-body setting to stop down to whatever is set on the aperture ring? But it doesn't have the aperture sensor cam, so it can't tell what the setting is on the len's aperture ring, and therefore can't do full- aperture metering, because it doesn't know how much to allow for the stopping down? This is the "crippled" bit? So the cams are actually sufficient for it to do stop-down metering on K and M lenses, but this hasn't been provided in the electronics/software/ mode controls? If one modifies a K or M lens to lock at a not-quite-mounted position, the lens then has a completely manual aperture: the spring in the lens stops it down to the setting on the aperture ring, but one has to view and focus while stopped down, or become extremely good at counting click-stops with the camera up at one's eye, or continually take it down to look at the aperture ring? I don't fancy the modifications anyway, I must admit. If I'm right about all this, I think my plans go: * Scanning 35mm negs/slides is a right pain, but six megapixels is enough to go digital. * It seems quite unlikely that Pentax will improve K/M mount compatibility in future models, since those lenses were a long time ago and they make no money from keeping them useful - although it's going to be worth checking what a production *istD can do. * Does anyone know of a third-party zoom that's A-mount compatible or better, with a focal length range including 24 to 60mm, with a wide maximum aperture? I'd want f2.0, really, but I'd settle for f2.8. Narrower than that, as per the Pentax lenses, doesn't feel attractive. --- John Dallman [EMAIL PROTECTED]
