On Sat, Jan 13, 2007 at 09:58:34PM +0100, Bertil Holmberg wrote: > Looks like the K10D brought back something very Pentax - the MTF - or > Modulation Transfer Factor. > > The excellent DCWatch Longterm Test #5 covers this in detail with > many example images taken with the DA 40, FA 43, and DA 16-45 mm lenses. > > http://dc.watch.impress.co.jp/cda/longterm/2007/01/12/5357.html > > I would be much obliged if you experts could explain what it is, why > we need it, and when to use it ;-)
The MTF is a measure of the resolving power (or sharpness) of the lens, and is dependent on aperture. FA and later lenses are capable of transmitting the MTF (Function, not Factor, IIRC) to the camera body. Some camera bodies (PZ-1p, MZ-S, *ist D, K10D ?) can use this data to automatically select the "best" aperture to use, if possible - a kind of "sharpness priority" program. The ability to transmit MTF data (and focus distance) is about the only difference between the "F" and the "FA" series of lenses. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
