Well, the first thing is, it does nothing to the focal length of your lens.
What happens is the sensor is smaller than a 35mm negative so you are only using the center of the lenses' covering power. To make a print you need more magnification (sort of like as if you made an 8x10 and then cropped a 5x7 out of it). This is exactly the same thing that would happen if you used a lens from the 645 on your 35mm body. Where the crap about the lenses changing focal length comes from is the idea (and it is only an idea) that it is now the equivalent of a lens that only could cover the smaller image. Back before the 35mm became the standard camera and there were all kinds of formats in common use no one would have even thought of this confusing nonsense. So what does change is the angle of view of the image, but that change would be exactly the same if you cropped the image as I mentioned above. But then, most of the people playing with digital cameras have no idea what angle of view is. As for switching to Canon, WHY? In the same price range the cameras are pretty similar performance wise, the only reason to change is if the Canon offered some feature you really need and can not get with Pentax. BEWARE, however, that most of the stuff people argue about performance wise is a few percentage points difference that would not be noticeable in normal usage at all. People will nit pick things to death. To give you an idea, my 50 year old Graphic press camera has a lens that has maybe 1/2 the performance of a new large format lens, you would not be able to see that difference in a 16x20 print, though I would probable have to use a 1/2 grade higher multi-contrast filter to make equivalent prints (the new lenses are noticeably more contrasty, in other words). Ciao, Graywolf http://pages.prodigy.net/graywolfphoto ----- Original Message ----- From: <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Saturday, June 21, 2003 2:18 PM 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 >
