> -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > For the *istD to emulate the field of view (hope that is the > correct term) > that a 50mm lens has on a film camera -- because the center > of the image is > essentially cropped by the APS sensor and "magnified" -- it > would have to use a > 33mm lens. In other words, a 33mm on the *istD would give the > same field of view > as a 50mm on a film camera (approx). Not sure about the rule > of thumb thing, > but for mathematical figuring, I guess you mean, it is 29mm.
You got that bit spot on. > But for him to look through the view finder and have the > image match his > other eye, the lens would actually have to be 82mm. This is > because with a DSLR, > the APS sensor crops the center of the image. So on a DSLR > the *normal vision* > lens is a 82, where on a film camera the *normal vision* lens > is a 50mm. You got that totally wrong though. If the viewfinder is .97* magnification it IS IRRELEVANT WHAT SIZE THE SENSOR IS - this has no bearing whatsoever on the image magnification in the viewfinder. It is only the angle of view that has changed in the viewfinder. A .97* vf on the ist is the same as a .97* vf on an MX is the same as a .97* vf on the hubble telescope! > In other words, because of the cropping, what is the normal > vision lens on a > film camera, a 50mm, would 82mm on a DSLR. But to emulate > what we are used to > as the normal vision lens on a film, camera, the 50mm, the > lens would be 33mm. > > In other other words, the normal vision lens for a DSLR is > actually not the > same as on a film camera. Your vision of the part of the viewfinder which is not 'masked off' is the same as your vision of the central part of a viewfinder on a 35mm, 645 or 6x7 camera with the same viewfinder magnification. > Not sure I put that the clearest way I could. It was very > hard figuring out > how to word those sentences. :-) I hope I have made it clearer. I have been perhaps a little blunt and to the point - please don't take this as aggressiveness, but you need to forget the 82mm thing NOW - it has no relevance. The sensor size also has no relevance to the MAGNIFICATION of the viewfinder - only its field of coverage, and then only if the manufacturer chooses to match the viewfinder to the area captured by the sensor. Hope this helps. Rob
