Quote: what would you pay for a good second hand one?
Probably no more than £250 but without a warranty I would want to pay less. Seems you can get them new for about £300.
Great bit of kit and if mine broke down I'd want another one.
Nice to see more of your macro shots Graeme....nice work Do you find the round highlights more annoying on the MP-E? I don't find they bother me on the 100mm as the round highlights tend to be much smaller at lower magnifications. FWIW I stick with manual mode for balancing the background aswell as full flash shots...set the manual exposure for the desired background exposure and tweak FEC for the foreground/subject (usually I prefer the subject shaded or backlit and the background well lit for fill flash). Saves taking my left hand off the end of the lens to change from M to Av and having to compensate for shaded foregrounds and dark subjects that could fool the ambient light meter. With a well shaded subject and a bright background you can have complete control over the background from white (eg deliberately blown sky) to black from deliberate underexposure.