Canon 100mm f2.8 1:1 pics

[dllavaneras]

The minimum focus distance and working distance are unaffected by whether the camera has a crop sensor or full frame sensor. The crop sensor obviously affects framing, but why would you need to figure an equivalent focal length for lighting macro work? I would just use 1/200 sec. (i.e. >1/180mm = 1/200).

The working distance doesn't change between cameras, but it does between lenses. The 100mm macro has a working distance of 15 cm, while the 180mm macro has a working distance of 30cm. When shooting macro, every tiny movement gets amplified, and I always like to have a shutter speed of 1/2xFL to ensure a good picture. Since when using the 180mm macro you have to be farther away, you have to have a very solid support to make sure you get a sharp pic. My field work doesn't allow for tripods and focusing rails, so I find the 100mm macro to be perfect.