Pentax K-r Flash
Pentax K-r Flash
The Pentax K-r 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 modes available depends on the current exposure mode. The flash can automatically pop-up as needed in Auto Picture, Portrait, Macro, Night Scene 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 can be used to switch the flash to manual mode, preventing it popping straight back up again when you press the shutter button if you don't want to use it.
The Pentax K-r's built-in flash has a guide number rating of 12 meters (39 feet) at ISO 100, translating to a range of about 14 feet at ISO 100 with an f/2.8 lens. Flash coverage is rated by Pentax at 28mm equivalent. 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. Even when set to controller, it still fires to provide timing for the slave flash during the exposure, but at greatly reduced strength, thus minimizing its effect on the flash balance. 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-r 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-r, and when the K-r'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-r's built-in flash will cut its exposure contribution to one-third.
The Pentax K-r 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
A reasonably powerful flash, with uneven coverage at wide-angle. Slightly higher than average exposure compensation required.
Coverage and Exposure. Flash coverage was rather uneven at wide-angle (18mm) with the 18-55mm kit lens, though that's not unusual and some of the fall-off is due to the lens itself. Coverage was much more uniform at telephoto (70mm), if a bit dim. In the Indoor flash test, the Pentax K-r's flash required +1.0 EV exposure compensation adjustment to get reasonably bright results. (Most cameras we've tested required about +0.7 EV for this scene.) We did notice that increasing the flash exposure compensation above +0.3 EV had only a small effect. The camera's Slow-Sync flash mode produced very bright results with no exposure compensation, though with a strong pinkish-orange cast from the room lighting.
ISO 100 Range. At 18mm, f/3.5 and ISO 100, flash shots started out quite dim at 6 feet but increased in brightness, peaking at about 9 feet. Exposures remained reasonably bright out to about 12 feet. At 55mm and f/5.6, flash exposure started out slightly dim at 6 feet, and decreased in brightness from there, falling off rapidly past 8 feet.
|Manufacturer-Specified Flash Range|
Manufacturer Specified Flash Test. The Pentax K-r's flash is rated with a GN of 12 meters at ISO 100. That translates to 11.2 feet at f/3.5 and about 7.0 feet at f/5.6, the maximum aperture of the 18-55mm kit lens at wide-angle and telephoto respectively. In the shots above, the K-r's flash under-performed somewhat compared to Pentax's specifications, producing slightly dim (but usable) exposures at the rated distances. The wide-angle shot is about 1/4 f-stop underexposed, while the tele shot is almost 1/2 f-stop underexposed. 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.