Marnie - in the way I understand it, a digital sensor uses only the central 2/3rds of the lens coverage, compared with film. So of your 50mm lens coverage, designed for a 40mm diameter circle, only a roughly 25mm circle is used. That's approximately the same angle of view as an 80mm lens - i.e. the focal length is magnified 1.6 times. No more worries about edge to edge sharpness here, nor light fall-off at larger apertures!
Rather than moving to Canon for (debatably) better AF, have you thought of trading your current Pentax body for an MZ-S or later Pentax? My view, which is shared by most MZ-S owners here, is that this is a very competent and well-built camera, far better than an Elan, with one of the fastest AF systems around. Alternatively, unless you have a really pressing need to go digital, why not wait a few months to see what Pentax does come up with, either with the *ist-D or a more mid-level *ist film body than currently announced? Economically, the cost of brand change is far worse when you have to switch lenses as well as bodies, and the three lenses you mention all seem pretty good quality to me. HTH John Coyle Brisbane, Australia ----- Original Message ----- From: <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Sunday, June 22, 2003 4:18 AM Subject: Dumb Q - Pentax FA/F Lenses on *ist D? > Removed newbie from subject line; guess I've been around long enough now not to be a rank newbie. :-) > > Okay, I am thinking about selling my Pentax gear and switching to Canon (mainly for the auto focus and maybe a bigger view finder -- yes, I will probably rent one first, if I can, before I decide -- probably the Elan 7e). > > But I probably should hold off until the *ist D materializes (and I am among the group that think it will materialize). I do have three zooms: Pentax FA 28-70, F 70-210, Tamron AF 70-300. These, as far as I understand, would all work on the *ist D just fine. (But I am not sure about the aperture priority stuff, whether I can set aperture myself on the *ist D.) > > The one thing I truly do not understand, even though I've read some threads about this -- is how would these alter regarding focal length on the *ist D? As far as I understand it (which isn't very far), it involves something about it not having a full sensor, so previous lens lengths have to be refigured and basically they come out shorter or something. > > Could someone explain this to me in very simple language? > > Thanks, Marnie aka Doe > >
