i recently started to use the (pixelHK) battery pack for my 580EX I & II. when the flash are being use, where are they getting the juice from? the battery pack? or the batteries inside the flash or both location? i remember reading somewhere (cant find it) that there is a setting on the flash that it will only use the juice from the battery pack?
i have both Powerex 2700 batteries & the Eneloop. what's better to use in the pack?