Originally posted by Ira If anyone wants me to email them my ESD piece that I did for the Florida's Turnpike....an easy to read 16-page study and lesson on the subject...PM me.
There is no way in helll you should have a unit powered up, and introduce an ESD event by handling a lens made of plastic. And plastic is the biggest conductor, worst material for tribo-electric charging, the biggest cause of ESD damage.
ESD is the major cause of damage/faulty operation of all bad cards.
ESD affects electrostatic sensitive components whether they are energised or not, most importantly they are generally most vulnerable out of circuit. A well designed circuit, such as one that has exposed contacts should have integrated ESD protection, it's all pretty basic from a design perspective.
The concept that the charge on the sensor due to it being powered would attract dust has been well and truly debunked many times. The voltages concerned are not remotely dust attractive, there may be a latent static charge on some polymer surfaces of the sensor due to a mechanical action (such as brushing with an brush that's not ESD safe) but in any case powering off the unit will not cause this type of static charge to dissipate.
For what it's worth I've never bothered to turn off any of my camera bodies (MZ-5n, MZ-S, *ist D, K10D, K20D, K-x) whilst changing lenses and I've never encountered a problem. However I don't own any SDM or power zoom lenses and if I did then I might tend to be more cautious as I the whole system seems to be a pretty poor implementation.