Pentax K-7 Exposure
Pentax K-7 Exposure
As with most SLRs, three metering methods are available on the Pentax K-7: Multi-segment, Center-Weighted, and Spot. All are accessed through the Metering mode lever below the exposure mode dial on the left side of the Pentax K7's top panel. In Multi-segment mode, the camera takes an exposure reading from 77 segments (up from 16 segments on the K20D) and chooses the best exposure based on brightness and contrast across much of the scene. The K-7 gives you the option to link the AF points to autoexposure in Multi-segment mode, via a Custom menu setting. Center-Weighted metering reads from the center of the frame, but from a fairly large area. Center-Weighted mode is automatically selected if a lens other than a DA, 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.)
An AE Lock button locks the current exposure settings whenever pressed, so you can independently lock exposure and focus. (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 the Setup menu, you can designate the function of the AE Lock button, and how it works in conjunction with the Shutter button.
In situations where exposure compensation is necessary, simply press the 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 -5 to +5 EV in increments of 1/3 or 1/2 EV, or you can use the Auto Exposure Bracketing function to automatically bracket an exposure in three or five-step increments of either 1/2 or 1/3 EV steps each. AEB is handy for those times when you want to make sure you get just the right exposure for a critical subject.
The Pentax K-7 also features an "Extended Bracketing" feature, which allows you to take a 3-shot bracket of White Balance, Saturation, Hue, High/Low Key Adjustment, Contrast, and Sharpness. Unlike exposure bracketing, three images are saved with each shot, as all these functions are performed in post-processing, so separate exposures are not required.
White balance options include Auto (which ranges from about 4,000K to 8,000K), Daylight (5,200K), Shade (8,000K), Cloudy (6,000K), Fluorescent Daylight Color (6,500K), Fluorescent Daylight White (5000K), Fluorescent Cool White (4200K), Fluorescent WarmWhite (3,000K), Tungsten (2,850K), Flash (5,400K), Color Temperature Enhancement (CTE) which used to retain and strengthen the color tone of the light source, Manual, and Color Temperature (3 settings). Pressing the AWB (left arrow) button brings up the White Balance menu. As mentioned, the Pentax K-7 offers a Color Temperature setting, which lets you choose from a range of Kelvin temperature settings, from 2,000K to 12,000K. The front e-Dial adjusts the value by 1-step (100K or 20 Mired), while the rear e-Dial adjusts by 10-steps (1,000K or 100 Mired). The Manual option is useful for basing the white balance on a white card. You can also adjust the white balance, controlling the amount of amber, green, blue, and magenta in the color balance using a 2D grid, in any of the selected modes. This ability to "tweak" the white balance, called White Balance Fine Tuning, is very helpful when dealing with difficult light sources.
The Pentax K-7 lets you adjust its light sensitivity, in 1, 1/2, or 1/3 EV steps, with options ranging from 100, to 3,200 ISO equivalents. An Expand Sensitivity Custom menu option allows up to ISO 6,400. An Auto ISO mode in which the camera selects an ISO appropriate to the subject's brightness is also provided. The Auto ISO system seems to adhere to the "1/focal-length for shutter speed" rule, meaning if the focal length is 100mm, the camera will attempt to select a shutter speed of 1/100s and choose a corresponding ISO speed. The default range for Auto ISO is 100 to 800, but you can set both the minimum and maximum ISO, as well as select from three parameters which determine how quickly ISO is boosted (slow, normal, and fast). Higher ISO settings are helpful when you want faster shutter speeds under normal lighting, to help freeze fast action.
Of course, as with all digital cameras, the higher ISO settings produce photos with more image noise, in much the same way that higher-ISO films show more film grain. To combat this problem, the K-7 offers a High-ISO Noise Reduction option through the Record menu, which reduces the amount of image noise at high ISOs. Options consist of Off, Low, Medium, and High, with a default of Medium. New for the Pentax K-7 is the ability to select at what ISO this NR kicks in. Options are ISO 200, 400, 800 (default), and 1600. 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 On (Auto), and Off.
Expanded Dynamic Range
The Pentax K-7 offers Expanded Dynamic Range options, which attempt to preserve highlights and/or shadows in high-contrast situations. Unlike the K20D, which offered just a single On/Off setting, the K-7 goes further, by offering separate Highlight Correction and Shadow Correction options. Highlight Correction has On/Off settings, while Shadow Correction has three strengths (Low, Medium, and High), along with Off. When Highlight Correction is enabled, the minimum sensitivity is ISO 200.
The Pentax K-7 also offers High Dynamic Range option, which captures three images in quick succession, one underexposed, one properly exposed, and one overexposed, then combines them in-camera. It uses highlight detail from the underexposed image, and shadow detail from the overexposed image to produce a high dynamic range composite. There are three setting available: Off, Standard, and Strong.
The Pentax K-7's Multiple Exposure feature allows you to combine 2 to 9 images into a single image as they are being captured. An option called Auto EV Adjustment varies the exposure of each individual shot so that the combined image has the same exposure as a normally exposed individual shot.
The Pentax K-7 offers the user the ability to modify pre-existing image profiles. The camera offers seven image style settings: Bright, Natural, Portrait, Landscape,Vibrant, Muted, and Monochrome. The following image parameters can be adjusted for each profile: Saturation (-4 to +4), Hue (-4 to +4), High/Low Key (-4 to +4), Contrast (-4 to +4), Contrast Highlight (-4 to +4), Contrast Shadow (-4 to +4), and Sharpness (-4 to +4). Saturation and Hue can only be adjusted when Monochrome is not selected. When using Monochrome, instead of Saturation and Hue, B&W Filter Effects and Toning options are provided. Filter effects consist of Green, Yellow, Orange, Red, Magenta, Blue, Cyan, and Infrared Color. Monochrome can be further modified with a Toning adjustment which allows you to dial in an amount of either selenium style processing (blues) or sepia style processing (browns). The 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 RGB color spaces in another menu.
The Pentax K-7 offers seven canned digital filter effects, plus a Custom setting that allows you to select the amount of each effect to your liking. The seven predefined filter effects are: Toy Camera, Retro, High Contrast, Extract Color, Soft, Star Burst, and Fish-eye. Parameters for each filter can be adjusted. The Custom Filter option allows you to adjust all the parameters: High Contrast (Off, +1 to +5), Soft Focus (Off, +1 to +3), Tone Break (Off, Red, Green, Blue, Yellow), Shading Type (6 types), Shading Level (-3 to +3), Invert Color (On, Off), Distortion Type (3 types), and Distortion Level (Off, Weak, Medium, Strong). You can see examples of the filters at work using our Still Life target on our Test Shots page. In addition to these capture filters, the K-7 offers eight more in playback mode (Monochrome, Color, Water Color, Pastel, Slim, Miniature, HDR, and Base Parameter Adjust), and up to 20 filters can be combined in playback mode.
Like most SLRs, the Pentax K-7 offers a number of Drive Modes. Modes include Single Frame (where one image is captured when the shutter release button is pressed, even if held), Continuous Lo, Continuous Hi, Self-timer, Remote, Bracketing, and Mirror Up. According to Pentax, "Continuous Lo" records JPEGs (using quality level "***") continuously until the card is full at approximately 3.3 frames-per-second, and "Continuous Hi" mode can record up to 40 frames at about 5.2 frames-per-second. When we tested with the highest JPEG quality level ("****"), we got 3.03 frames-per-second for 33 frames, and 5.21 frames-per-second for 20 frames. (Note that our test target is difficult to compress, so buffer lengths using typical subjects are usually better.)
The Pentax K-7 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, 3-second delayed release, or continuous where the first press of the remote starts continuous shooting and a second press stops the burst. The Pentax K-7 has an IR receiver for wireless remotes in the front as well as in the back, which is a really nice feature. A traditional Auto Exposure Bracketing mode is also provided (in addition to the previously mentioned Extended Bracketing), where 3 or 5 frames can be taken with programmable bracket value and order. Finally, a Mirror Lock-up function is also provided to eliminate camera shake during exposure due to mirror slap. When enabled, the first Shutter button press raises the mirror, and the second takes the exposure. An option is available to enable Mirror Lockup when using a remote control.
The K-7 also offers an Interval Shooting mode where the camera can take pictures by itself on a regular basis, used for time-lapse photography. The interval can be programmed between 1 second and 24 hours, the number of shots between 1 and 99, and the starting time can be immediate or at a set time.
As mentioned elsewhere in the review, the Pentax K-7's Shake Reduction system has the ability to correct for rotational motion. Time and experience (and possibly measurement) will tell how much difference the rotational correction capability of the Pentax K-7's SR system will make in capturing sharp images with slow shutter speeds. The ability to rotate the Pentax K-7's image sensor opens up what might be a more interesting application, though, and one that's potentially more broadly useful.
Given that the camera contains accelerometers (used for determining vertical vs horizontal orientation) that let it precisely determine the camera's position (and hence any tilt relative to an exactly horizontal or vertical position), it makes sense to combine that capability with its rotation-capable SR actuators to come up with an entirely new feature: Automatic horizon leveling, or Automatic Horizon Correction, as it's called on the Pentax K-7's menu system.
What a brilliant idea! Tilted horizons are a huge problem for amateur photographers, and even not-so-amateur ones who are in a hurry, or who are simply paying more attention to the subject at the moment of exposure than to the orientation of the camera. Trust us, paying attention to both subject and camera orientation simultaneously is harder to learn than you'd think.
In the animation at right, the actual angle of the original, tilted shot was 1.3 degrees, and the camera corrected it to a tilt of just 0.3, exactly matching Pentax's spec for the +/- 1 degree correction.
Even if you don't choose to use its automatic Horizon Correction function, the Pentax K7 has a useful Electronic Level feature that tells you whether your camera is level or not, in both landscape and portrait orientation. When enabled via a checkbox on Record Menu 3, the bar graph on the top-panel LCD readout that normally shows exposure compensation instead shows a row of dots indicating whether the camera is tilted or not, and in which direction. (Like a bubble level, the dots extend toward the side of the camera that's higher.) The exposure display inside the viewfinder likewise converts to a level display, but you can toggle both back and forth between exposure and level display by pressing the +/- button on the camera's top panel. Interestingly, when the Horizon Correction option is enabled, these displays don't indicate an out-of-level condition until the camera is tilted more than the +/-1 degree angle that the Horizon Correction feature can fix. Each dot on the top LCD and in the viewfinder display appear to correspond to about 1/3 degree of tilt.
In Live View mode, a little bar graph display appears in the upper right corner of the LCD screen, displaying a series of dots to indicate tilt angle. When the camera is level, a green line appears to indicate that fact. The scale of the tilt indicator on the rear LCD seems to be slightly expanded over that of the top panel readout and viewfinder displays, with each dot corresponding to 1/4 degree of tilt.
The Electronic Level display in Live View mode is a bit more sensitive than that shown in the viewfinder and top-panel data readout.
When the Horizon Correction option is active, two white pips appear to mark the limits of its correction ability, and the level-indicating behavior of the graph changes accordingly.
When the Horizon Correction feature is enabled, two pips appear under the bar graph on the LCD display, indicating the +/-1 degree limit that HC can compensate for. Likewise, the green line appears when the tilt is within that +/-1 degree window, and the dots on the bar graph are green. Outside the +/-1 degree range, the dots turn yellow and the green line disappears. When the dots reach the limit of their range, they flash red to indicate an out-of-range condition. The animated screenshots above show the Electronic Level display at work in Live View mode, both with and without the Horizon Correction feature enabled.
The images above were taken from our standardized test shots. For a collection of more pictorial photos, see our Pentax K-7 Photo Gallery .
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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.