I got this off photo.net:
"I´ve played with the USM version in a shop recently, plus I´ve looked at printed pictures of the USM version. In my opinion Canon has made a big mistake in the optical construction (or a bad compromise) - under certain circumstances there is a terrible or weird background blur (double line bokeh), eg. if you photograph a flower, the unsharp part of the flower´s stem may turn into a structure which looks like two stems. Disgusting. I´d go for the older version.
-- Tobias Mennle , August 17, 2003; 11:07 A.M. Eastern "
I know 100mm f2.8 is a really sharp lense but can anyone can testify to the above comment by that guy ?
"I´ve played with the USM version in a shop recently, plus I´ve looked at printed pictures of the USM version. In my opinion Canon has made a big mistake in the optical construction (or a bad compromise) - under certain circumstances there is a terrible or weird background blur (double line bokeh), eg. if you photograph a flower, the unsharp part of the flower´s stem may turn into a structure which looks like two stems. Disgusting. I´d go for the older version.
-- Tobias Mennle , August 17, 2003; 11:07 A.M. Eastern "
I know 100mm f2.8 is a really sharp lense but can anyone can testify to the above comment by that guy ?