Archived posting to the Leica Users Group, 2005/02/12
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Dan, Your question includes assumptions as to resolving power of the recording media, tripod use or not, and the size of enlargement. Assuming a truly outstanding recording media and the use of a tripod and an enlargement factor of 10X; I suspect that a difference of 10% will be detectable. So you should just make out the difference between one lens showing 90% at a given point and one showing 80% or so. If the enlargement factor increases, then the spread will decrease. At a 20X enlargement then you should see the difference in a 90% and an 85% lens. I think this is why the wide angle zooms for Canon have taken such a hit on the full frame sensor. If you look at the MTF charts, the percent contrast in the corners is about 10%. Combine that with high incident angles and micro lenses you are almost guaranteed low resolution color fringed images in the outer zones. Combine that with the pixel peepers desire for perfection in 100% PS views, no understanding of viewing distance, and you get unreasonable demands. A lens is just a tool, sometimes; a truly flawed lens will make wonderful images. Don dorysrus@mindspring.com -----Original Message----- From: lug-bounces+dorysrus=mindspring.com@leica-users.org [mailto:lug-bounces+dorysrus=mindspring.com@leica-users.org] On Behalf Of Dan C Sent: Saturday, February 12, 2005 4:58 PM To: Leica Users Group Subject: Re: [Leica] MTF Data What no-one has ever been able to explain to me is how to determine how big a change on an MTF chart is required before a visible change becomes apparent in a photograph. -dan c. At 04:50 PM 12-02-05 -0500, Benjamin Marks wrote: >Anyone know of a good primmer on-line (or care to explain) how to read an >MTF graph? This was spurred by looking at the MTF graphs on Leica's >web-site for the 2/35 and 1.4/35 lenses and going "hunh" . . . Not that MTF >graphs are the be-all and end-all, but I've been sauntering through my >photographic life for the last 20 years without knowing what they mean. (not >much of a theory-head when it comes to optics). So, here's the softball >question: what kind of numbers (or what kind of curves) make a lens >"better" in MTF land? What about the 1.4/35's graph indicates that it is >such a winner? > >bemusedly, > >Ben Marks >benjamin marks at verizon dot net > > >_______________________________________________ >Leica Users Group. >See http://leica-users.org/mailman/listinfo/lug for more information > _______________________________________________ Leica Users Group. See http://leica-users.org/mailman/listinfo/lug for more information