Alkaline batteries do not have a constant voltage output. This constant voltage output will ensure that all the power in the battery is used. If the voltage drops too low, the camera may not turn on even though there is still power in the battery.
We highly recommend using either rechargeable NiMH batteries 2300mAh or higher (such as the BU-90SA NiMH rechargeable battery set) or lithium type batteries.
Please note that this is only a recommendation and the use of alkaline batteries will not harm the camera in any way.