AF540FGZ II auto flash units for PENTAX lens-interchangeable digital cameras, featuring weather-resistant construction & LED light for movie & still-image recording AF540FGZII is a weather-resistant auto flash unit for PENTAX lens interchangeable digital camera with a maximum guide number of 54 at ISO 100/m. This unit is designed to provide solid, dependable operation even under harsh outdoor conditions including rain & fog. With 28 seals applied to crucial parts of the unit body including the hotshoe, these flash units feature highly dependable weather-resistant construction. By coupling one of them with a camera body & a lens that feature the same weather-resistant construction, the user can create a highly reliable weather-resistant digital imaging system that assures solid performance even in harsh outdoor conditions, such as in the rain or at locations subject to splashes & dust. Both models incorporate a newly designed, high-intensity fixed-light LED light in their body. This white LED light comes in handy not only for close-distance movie recording, but also for still-image shooting requiring extended exposures. It also functions as a catch light in portraiture & an AF assist light in the dark.* * The AF assist light function is available with 645D, K-r, K-5, K-30, K-5 II, K-5 II s, K-50 & K-500 camera bodies. The camera’s firmware must be updated to the latest version to support this function. The user can customize the flash operation by presetting as many as nine different flash functions to their preference, including the on/off of the catch-light function using the LED light & the choice of the flash discharge mode in still-image shooting. Both models provide a variety of flash discharge modes, ** ranging from the advanced P-TTL auto flash mode in which the flash’s preliminary emission is detected by the camera’s light sensor to accurately control the main discharge level for proper exposure, to manual flash, high-shutter-speed synchronization & wireless P-TTL auto flash. ** Available flash discharge modes may vary depending on the camera body in use.