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.
Flash Test Results
Coverage and Range
Good performance at close range, with uneven coverage at wide-angle. Lower than average exposure compensation required.
Coverage and Exposure. Flash coverage was uneven at wide-angle (18mm) with the 18-55mm kit lens. Coverage was much more uniform at telephoto (55mm). In the Indoor test, the Pentax K-x's flash required no exposure compensation adjustment to get good, albeit quite bright results. (Most cameras we've tested required about +0.7 EV for this scene.) The camera's Slow-Sync flash mode produced slightly bright but more even results with no exposure compensation, though with a stronger pinkish-orange cast from the room lighting.
ISO 100 Range. At 18mm and ISO 100, flash shots started out bright at 6 feet, peaked in brightness at about 7 feet, and remained fairly bright out to about 11 feet. At 55mm, flash exposure was bright at 6 feet, but decreased in brightness from that point on.
|Manufacturer-Specified Flash Range|
Manufacturer Specified Flash Test. The Pentax K-x's flash is rated with a GN of 16 meters at ISO 200. That translates to 4.6 meters or 15 feet at f/3.5, and 2.9 meters or 9.4 feet at f/5.6. In the shots above, the K-x performed about as Pentax says it will, producing good exposures at the rated distances. Our standard test method for flash range uses a fixed setting of ISO 100, to provide a fair basis of comparison between cameras. We've now 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.
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Note: For details, test results, and analysis of the many tests done with this camera, please click on the tabs at the beginning of the review or below.