Christiane, This term "magnification" bugs me. The reason I started this thread was to understand it. If it is solely a matter of "angle of view" (as Karl says and nobody counters),-leaving aside film grain&film impurities-the main reason for carrying lots of glass must be only for the photographer to be able to see and compose the view BEFORE taking the picture. I also try to leave the glass quality and MTF's, etc. out of the equations. BTW, in the DSLR world, there exists no grain, but the image formed consists of pixels. izzet > -----Original Message----- > From: owner-photoforum@listserver.isc.rit.edu > [mailto:owner-photoforum@listserver.isc.rit.edu] On Behalf Of > Christiane Roh > Sent: Sunday, September 08, 2002 11:40 AM > To: List for Photo/Imaging Educators - Professionals - Students > Subject: Re: Two basic and dumb questions about lenses > > > Le 8.9.2002 9:10, « ITzzet » <izzet@vizo.com> a écrit : > > > Then does it follow from here that > > 1-The ONLY reason we loose resolution when we blow up an > image on the > > film is because of the grain and other impurities of the > film itself, > > and 2-The resolution power of the optical system (lens) is infinite. > > No, 1) isn't the only reason.. 2) accounts for it too; the > limit is the size of the circle of confusion we are ready to > accept and this doesn't only depends upon the grain. Just > think about it : some lenses are better than else and thus > allows greater magnification, all lenses aren't equal and > increasing magnification will makes their defects more apparent. > > If the perspective and spatial relationship stay the same, > the image quality degrades itself a lot due to the > magnification : why would we need to buy all these expansive > lenses and drag them around if a single one could do it all ? > Even digital SLRs bodies need several lenses although there > is no grain in digital pictures.. > > --- > Incoming mail is certified Virus Free. > Checked by AVG anti-virus system (http://www.grisoft.com). > Version: 6.0.385 / Virus Database: 217 - Release Date: 04.09.2002 > >
