At its heart, the HP Photosmart R847 is simply a scaled-up version of the HP Photosmart R837. Like its predecessor, the R847 uses a slightly chunky metal body with a sliding lens cover that reminds me more than a little of the Sony Cyber-shot T-series cameras. It carries the same 3-inch LCD screen on the back panel, leaving just enough room for a large joypad and a comfortable, L-shaped zoom rocker.
HP designed the R847 to be simple to use, like the R837. While you can manually change settings like sensitivity (aka ISO) and white balance, you'll probably spend most of your time in the camera's automatic or various scene preset modes. Like most compact snapshot cameras, the R847 lacks more advanced exposure controls like aperture priority and shutter priority. While you can't change many settings while shooting, you can at least tweak your photos once they're in the camera with its myriad photo editing commands, also carried over from the R837.
Its 8-megapixel sensor stands out as the most notable improvement over the camera's 7-megapixel cousin, but it's not the only change. The R847 can reach up to ISO 1600, completely overtaking the R837's ISO 400 limit. Plus, while the R837 uses an HP Precision lens, the R847 uses a Fuji nonbranded lens. They're both 39mm-to-118mm equivalent lenses and they both share the same completely internal mechanism, however, and present little functional difference.
Despite its higher resolution, the R847 consistently beat its little brother in our lab tests. After 1.9 seconds from power-on to first shot, it could take a new shot once every 1.3 seconds with the onboard flash turned off. With the flash enabled, that wait increased to a still-good 1.8 seconds. The shutter responded quickly, lagging only 0.5 second with our high-contrast target and 1 second with our low-contrast target. Only in burst mode did the R847 lose to its predecessor, taking three full-resolution photos in 2.2 seconds for a rate of 1.4 frames per second, compared to the R837's 2.1 frames per second. This slower burst rate can probably be attributed to the R847's higher resolution.