Pentax K-3 Flash

Coverage and Range
A fairly powerful built-in flash, with somewhat narrow coverage. About average exposure compensation required.

Coverage and Exposure. Flash coverage is a little narrow at wide angle (18mm) with the 18-135mm kit lens, though we've seen much worse. Coverage is more uniform at telephoto (135mm), but extreme corners are still a little dim, though some of fall-off is due to the lens itself. In our Indoor Portrait test, the Pentax K-3's flash required +0.7 EV flash exposure compensation to get bright results, which is about average for this scene. Auto white balance was however quite cool. The camera's Slow-Sync flash mode produced bright results with no exposure compensation, though with a strong yellow-orange cast from the ambient room lighting.

ISO 200 Range. At 18mm, f/3.5 and ISO 200, our flash target remains bright out to 12 feet, though images are still usable out to about 14 feet. Surprisingly, at 135mm and f/5.6, flash range is also about 12 feet, and flash shots usable to about 14 feet.

Manufacturer Specified Flash Test. The Pentax K-3's flash is rated with a GN of 13 meters at ISO 100. That translates to about 12.2 feet at f/3.5 and about 7.6 feet at f/5.6, the maximum aperture of the 18-135mm kit lens at wide angle and telephoto respectively. In the shots above, the K-3's flash performed to specification at both wide angle and telephoto, underexposing our flash target by a negligible amount (~1/10 EV or less). Our standard test method for flash range uses a fixed setting of ISO 200, to provide a fair basis of comparison between cameras. We've also begun shooting two shots using the manufacturer-specified camera settings, at the range the company claims for the camera, to assess the validity of the specific claims.