> -----Original Message----- > From: [EMAIL PROTECTED] [mailto:owner-eos@;a1.nl]On Behalf Of Bill Jameson > Sent: Monday, October 21, 2002 10:26 AM > To: [EMAIL PROTECTED] > Subject: Re: EOS I too can understand MTF data- almost > > > Henning Wulff <[EMAIL PROTECTED]> wrote (in part): > ... > > The tests are usually done at various spatial frequencies, such as 10 > > line pairs per mm, and 30lp/mm. As Canon doesn't tell use which they > > use, these charts become a lot less useful. The performance at > > 10lp/mm is usually much more important than that at 30 or 40lp/mm, > > and testing at 5lp/mm and 15lp/mm would of course give a lot higher > > values than testing at 15lp/mm and 40lp/mm. Therefore the _most_ one > > can do is assume that Canon tested all lenses at the same > > frequencies, in exactly the same fashion, and then one could, with a > > fair bit of experience, compare lenses of the same apertures and > > focal lengths. > > > > In this case, the graphs are almost useless. > ... > > Hopefully someone will correct me if I am wrong, but Canon did give the > frequencies for the spatial pairs where the MTF charts were originally > published: Lens Work II. Problem is that the charts have been > reproduced on > the web without the rather lengthy explanations, including the fequencies, > that were published in the back of Lens Work II. > > Bill Jameson >
Hi Bill, Contrary to the previous poster's comments, the charts are for exactly the purpose of comparing relative lens performance within Canon's lens line. Nope you are mostly right, the charts show data for each lens for 10 lp/mm and 30 lp/mm both wide open and at f/8. The charts as shown on the Canon web site are fully explained just as they are in Lens Work II, just click on the "how to read mtf chart" at the bottom of each chart. Cheers/Chip * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
