New Canon 100mm 2.8L Macro IS potential issue with teleconvertors

on my 5D2 with the 12.5mm extension and Canon 1.4x, the 100 IS hunts a fair bit then finds focus -- max focus is about 3 1/2 feet - maybe marginally useable for macro if you've got enough extension rings

the Kenko teleplus hunts quite badly but finds focus - this may take 10 seconds - probably not useable

comment on the lens itself - at large apertures significantly sharper than the 100M, stopped down to f8-f16 no real difference. subjectively i think it focuses enough faster than the 100M to be useful - on my last trip i seemed to have a higher hit rate on small fish than with the old lens (on 20D). On land it is certainly a more useful lens. The IS really does open up some additional hand-held macro possibilities. I'd be interested in hearing how the macro distance focusing works on the 7D as that should be useful both wet and dry

Try doing it again but be sure that you attach the teleconverter to the lens and then attach the whole lot to the camera - there are several reports on the web that this makes a big difference.

Sorry this does not make any difference with the 1DsMkII. Do you think this will convince my wife to let me upgrade to a 1DsMKIV? ;-)

imasleeper