Pentax K-r Exposure
Pentax K-r Exposure
In Multi-segment mode, the camera takes an exposure reading from 16 segments and chooses the best exposure based on brightness and contrast across much of the scene. The K-r gives you the option to link the AF points to autoexposure in Multi-segment mode, via Custom Function 6, "Link AE to AF Point", but the default is to determine exposure without considering AF point location.
Center-Weighted metering reads from the center of the frame, but from a fairly large area. Center-Weighted mode is automatically selected instead of Multi-segment mode, if a lens other than a DA, DA L, D FA, FA J, FA, F, or A lens is mounted, or when the lens aperture ring is set at other than "A."
Spot metering simply reads the exposure from the very center of the image, so you can pinpoint the specific area of the photograph you want properly exposed. (Spot metering is very handy when you have a subject that's backlit, or that has a very different brightness, either lighter or darker, than the background.)
By default, the AF / AE Lock button triggers autofocus, but you can program it to lock the current exposure settings whenever pressed. (AE Lock is useful when you want to base your exposure on an off-center subject. Point the camera at the subject, lock the exposure, then recompose your shot however you like. Your subject will be correctly exposed, regardless of what might be in the center of the frame when you finally snap the shutter.) Through screen four of the Record menu, you can designate the function of the AF / AE Lock button, and how it works in conjunction with the Shutter button and Autofocus system.
In situations where exposure compensation is necessary, simply press the top panel Exposure Compensation button and turn the e-dial (in all exposure modes except Manual) and the exposure value (EV) will display in the viewfinder and on the LCDs. EV compensation ranges from -3 to +3 EV in increments of 1/3 or 1/2 EV, or you can use the Auto Exposure Bracketing function to automatically capture a bracketed exposure with three frames, varying the exposure between shots by as much as 3.0EV in either 1/2 or 1/3 EV increments. You can control the bracketing order for AEB sequences using Custom Function 7. AEB is handy for those times when you want to make sure you get just the right exposure for a critical subject.
It's worth noting that the effects of exposure compensation and auto exposure bracketing are additive -- that is to say, if you dial in 3.0EV of exposure compensation, and shoot bracketed exposure, it's possible for one frame to vary as much as 6.0EV from the metered exposure.
Pressing the AWB (left arrow) button brings up the White Balance menu. The Manual setting is useful for basing the white balance on a white card. You can also adjust the K-r in any white balance mode so as to control the amount of amber, green, blue, and magenta in the color balance using a 2D grid. This ability to "tweak" the white balance, called White Balance Fine Tuning, is very helpful when dealing with difficult light sources.
When using the K-r's Cross Processing function, white balance cannot be adjusted.
An Auto ISO mode in which the camera selects an ISO appropriate to the subject's brightness is also provided. The default range for Auto ISO is from the base ISO sensitivity to 3,200, but you can set maximum ISO limit manually . Higher ISO settings are helpful when you want faster shutter speeds under normal lighting, to help freeze fast action.
The Auto and Custom options are both new for the Pentax K-r, and the latter provides an unusually fine-grained degree of control over the camera's high ISO noise reduction behavior. When the Custom mode is enabled, a different setting (Off, Low, Medium, or High) can be configured for every full-stop ISO sensitivity available, including those in the expanded range. If the sensitivity step size is configured to match an exposure compensation step size of either 1/3 or 1/2 EV, the additional sensitivities share a noise reduction setting with the full-stop sensitivity below them, but that's still an unusually fine level of control over high ISO NR -- at most there are three sensitivities required to share any individual NR setting.
A second type of Noise Reduction called Slow Shutter Speed NR subtracts a second, dark frame to remove noise and hot-pixels depending on the conditions, such as shutter speed, sensitivity, and internal temperature. Settings for that option are Auto, On, or Off, where the K-x simply offered On and Off settings. The On setting applies noise reduction on all exposures longer than one second, while the Auto option applies NR only when the camera deems necessary, taking into consideration the shutter speed, ISO sensitivity, and the camera's internal temperature level.
Expanded Dynamic Range
Another difference has perhaps even greater implications for real-world usage. In the K-x, HDR imaging was only useful when shooting on a tripod, as even slight movement between capture of the source images would otherwise lead to artifacts in the final image. The K-r can now automatically align the images before combining them, and so is usable handheld, so long as your subject is reasonably static, and your hand somewhat steady.
When enabled, the HDR mode precludes the use of Raw file format, bulb shutter speed, multi exposure, interval shooting, cross processing, and digital filters. Also, drive modes except single-frame, self-timer, remote control, and remote w/ timer are disabled. Each HDR capture requires a brief processing time to create the final image, and the three source images can't be saved -- they're discarded when processing is complete, which is something we'd love to see changed in future firmware. (On those occasions where the in-camera HDR merge isn't optimal, it might be possible to do a better job manually on a PC, or it might still be desirable to have a copy of the standard exposure image).
An option called Auto EV Adjustment can average the exposure of each individual shot so that the combined image has the same brightness as a normally exposed individual shot. When disabled, the process is additive, just like shooting multi-exposures on film. To understand the difference, imagine a two-frame exposure where the same point is mid-grey in one image, and near-white in the other image. With auto EV adjust disabled, the same point in the final image will be completely white (clipped in every channel). With the adjustment enabled, the same area will have a brightness halfway between that of the same point in the brighter and darker images. An interesting usage of this feature is that multiple frames can be combined in-camera with averaged exposure to yield a single image with reduced noise / an effective exposure longer than would ordinarily be the case without the use of a neutral density filter.
When using Cross Processing, the Custom Image mode is fixed to Bright. You also can't control the Custom Image mode when the K-r's Mode dial is set to any position other than P, Sv, Tv, Av, or M. The adjustment interface allows you to take a sample image with the preview button, or shows you the last image shot, to use as a reference image; adjustments made in the interface are simulated in the sample image. Of course, you can also select between sRGB and Adobe RGBcolor spaces in another menu.
The pre-capture filters are almost identical to those in the previous K-x model, with two small exceptions. The Extract Color filter can now extract two colors, rather than one, and the Starburst filter adds four new effect shapes. In addition to these pre-capture filters, the K-r offers ten more in playback mode (Sketch Filter, Water Color, Pastel, Posterization, Miniature, Base Parameter Adjust, Monochrome, Color, Slim, and HDR), and up to 20 filters can be combined in playback mode.
Use of the cross-processing mode isn't possible while shooting Raw images, multi-exposures, extended bracketing, or high dynamic range captures. With cross-processing enabled, access to the custom image and white balance settings are also disabled.
The Pentax K-r also offers two Self-Timer modes for self-portraits or those occasions when you don't want to risk camera shake on a long exposure by pressing the Shutter button to trip the shutter. You can choose between a two- or 12-second countdown. The two-second countdown is useful for times when you're taking a long exposure with the camera on a tripod, and you want to minimize any camera shake from pressing the Shutter button. In this mode, the mirror is raised immediately after pressing the shutter, giving time vibrations to dampen before the exposure. The Remote Control modes offered are immediate release, or 3-second delayed release. The Pentax K-r has an IR receiver for wireless remotes in the front, but none in the back, so you'll need to stand in front of the camera, or reach in front of the hand grip before tripping the remote. Finally, an Exposure Bracketing mode is also provided, where 3 frames can be capture with as much as 2.0 EV steps between frames, and this allows the bracketing order to be changed.
The images above were taken from our standardized test shots. For a collection of more pictorial photos, see our Pentax K-r Photo Gallery .
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