Pentax K-x Flash

Pentax K-x Flash

The Pentax K-x features a built-in, pop-up flash, which operates in either Auto, Flash On (forced flash), Auto + Red-eye reduction, Flash On + Red-eye reduction, Slow-sync, Slow-sync + Red-eye reduction, Trailing Curtain Sync, or Wireless mode. The flash can automatically pop-up as needed in Auto Picture, Portrait, Macro, Night Portrait, or several of the Scene modes (Surf & Snow, Food, Kids, and Pet). In Night Scene, Sunset, Stage Lighting, Candlelight, and Museum modes, the flash is disabled altogether. In other modes, the flash is released from its compartment by pressing the Flash Up button to the left of the viewfinder. Close it again by pushing the flash head back down. The same button is used to disable the flash when it has popped up automatically, but you prefer not to use it.

The Pentax K-x's built-in flash has a guide number rating of 16 meters (52 feet) at ISO 200, or about 11.3 meters (37 feet) at ISO 100. That's a little weaker than most SLR built-in flashes (the average GN is about 12 meters), translating to a range of about 15 feet at ISO 200 with an f/3.5 lens. A Flash Exposure Compensation feature controls the flash exposure -2.0 to +1.0 stops in 1/2 or 1/3-stop increments. Maximum sync speed is 1/180 second, though if an external flash that supports high-speed sync is used, such as the Pentax AF540FGZ or AF360FGZ, maximum shutter speed with flash is 1/6,000 second.

In Wireless mode, the built-in flash can be used as a controller to multiple wireless slave flashes (including the Pentax AF540FGZ and/or AF360FGZ flash units). The built-in flash can be set to contribute to the exposure, or to act only as a controller. The Pentax wireless flash system offers four control channels, so up to four camera/flash setups can be used in the same area without interfering with each other. The K-x can connect on any of the four control channels: You program it by setting a flash unit to the desired channel, attaching that flash to the camera and then half-pressing the shutter button. This sets the camera to the channel the flash was set up for. After this, the flash may be removed and used as a remote unit, controlled by the camera.

Normally, all flashes used (whether on-camera or remote) contribute equally to the exposure, however each external flash can be set to one of the following ratios: 1/1, 2/3, 1/2 or 1/3. Additionally, each flash can be adjusted to under- or overexpose in 0.5 stop increments from -3.0 stops to +1.0 stop. All of this is relative to the overall flash exposure that can be adjusted on the camera by from -2.0 stops to +1.0 stop. Alternately, the Pentax flash units offer a Contrast-Control-Sync mode (CCS for short), which drops a flash's power. Units set to CCS mode can thus be used to provide "fill" illumination. When used with the K-x, and when the K-x's internal flash is also contributing to the exposure, the external flash in CCS mode will cut its output to two-thirds, while the K-x's built-in flash will cut its exposure contribution to one-third.

The Pentax K-x also has a top-mounted hot shoe for attaching an external flash unit. Like most consumer SLRs, a PC-sync terminal is not provided.