You can use CR123 Batteries with the Compur Electronic Shutters and they work fine. These are 3v batteries vs the 4.5 of the orginial so there should be no harm done to the shutter by using them. There are also 3.6V Lithium Cell batteries that are closer to the orignial 4.5v out now. You can use aluminum foil or other conductive material as a "spacer" and to fit them in the larger battery holder.