Media & Batteries
Each camera is equipped with proprietary rechargable lithium-ion batteries. Each camera has one battery that is then used for image capture, writing the file to the storage media, powering the LCD monitor and the built-in flash, if necessary. By the way, all three cameras do have an external “hot shoe” for mounting an external flash. If you plan on taking large numbers of pictures that require flash, we would recommend using an external flash unit and saving your battery power.
Our experience with these three cameras showed that we could get several hundreds of images on a full charge. We did try to capture an equal number of pictures with and without flash using each camera. Our usage seemed to even out at between five hundred and six hundred images on a full charge for all three cameras. Granted, most people will not be taking that many pictures on any one day, however, we would strongly recommend that you purchase an extra battery for your camera tote. Have both batteries fully charged before you hit the road, since you could be more than a day from an electrical outlet or you could forget the recharger at home, accidentally.
Your images will be written as individual files to the storage media that you slip into the camera's card slot. Both the Canon T1i and the Nikon D5000 utilize an SD form factor storage card. The Olympus E-620 has two card slots: One xD slot and one CompactFlash (CF) storage card slot. While all of these cards make use of flash memory, thus making them "equal" in the eyes of many photographers, some are more equal than others, in our opinion.
The xD form factor has really not caught on to the extent of the CF or SD cards. It does not have the same larger storage capacities as other form factors (it is limited to 2GB cards of storage) and xD cards are not as readily available. Thankfully, Olympus decided to include the CF card slot. And with the CF slot, this camera can access cards up to 32 GB in capacity. The Canon and Nikon, using the SD card, also have capacities up to 32 GB.
For Media & Batteries, we would rate all three cameras at 4.