Canon 100mm F2.8

[Overread]

sorry - yes manual focusing - av mode works very well (I think f13 is a common insect aperture).
In addition to TC's comment, if you want to shoot off a tripod and not hand held, then get a focusing rail which will let you slide the camera back and forth on the tripod head. This lets you move it in and out of focus easier than moving the whole tripod setup (which is very crude when dealing with such fine depths of field)