Pentax K-7 at a glance:
- 14.6 million effective pixels
- Live View on 3in, 920,000-dot LCD screen
- HD video at 640×416, 1536×1024 or 1280×720 pixels (16:9) at 30fps
- Moving, self-levelling sensor
- Street price approx £1,190
Pentax K-7 review – Introduction:
At the official press launch of the Pentax K-7, Pentax allowed the journalists to retain the pre-production samples. Although at the time Pentax UK’s representatives believed that these cameras needed just a final firmware upgrade to bring them up to full production specification, their Japanese colleagues later announced that a slight modification was required to optimise noise control, especially at high sensitivity settings.
While this information was made available at the same time as the firmware upgrade was sent, it caused problems for some testers who were already committed to publishing a review.
At AP we have a policy of testing only full production model cameras so our tests accurately reflect the buyer’s experience. Consequently, while this test of the Pentax K-7 may not be the first, it is the first of a full production sample.
As Pentax’s first real high-end enthusiast DSLR, the 14.6-million-effective-pixel K-7 faces tough competition from the likes of the Canon EOS 50D and the new Nikon D300s.
However, it isn’t just a ‘me too’ model, as it has a few unique features such as a sensor that can automatically rotate by as much as 2° to correct a sloping horizon and an in-camera HDR mode.
It is also very compact for a camera of this level, and has 77 weatherproof seals to keep moisture and dust at bay. The prospect of a small, highly functional DSLR that might have the class-leading detail resolution of the Pentax K20D is truly enticing.
The Pentax K-7 is a digital SLR camera, and though smaller and lighter than both the Canon EOS 50D and Nikon D300s, it has a traditional reflex mirror and an optical viewfinder. It also features a newly developed 14.6-million-effective-pixel CMOS sensor measuring 23.4×15.6mm with four-channel data read-out for faster image processing.
Pentax K-7 File formats
As with earlier enthusiast-level Pentax DSLRs, the K-7 allows images to be saved in one of two raw formats: the widely compatible Adobe DNG and Pentax’s own PEF format. As before, I have been unable to discern any difference between the quality of these two formats, but the choice has a small impact on the number of images that can be shot continuously.
When set to shoot in its high continuous mode, the K-7 can capture images at 5.2fps for up to around 30 premium JPEG images, 15 PEF or 14 DNG files. Also, the camera is ready to take another shot just a whisker faster after taking a PEF image than it is with a DNG file.
Pentax K-7 Shake reduction and built-in-level
Like the Pentax K20D, the K-7 has a sensor-shifting Shake Reduction (SR) stabilisation system and it is claimed to reduce the impact of camera shake so the camera can be handheld at shutter speeds approximately 2.5-4EV slower than usual.
A bit of lateral thinking has enabled this mechanism to be used in conjunction with the K-7’s built-in level, so the sensor can be set to rotate automatically by up to 2° to correct a sloping horizon. Those who prefer to trust the evidence of their own eyes, however, can use the level indicators marked in 1° to ±5° in both the viewfinder and LCD screen to guide the orientation of the camera in portrait and landscape format.
Pentax K-7 Sensor
In addition, when an image is being composed on the LCD screen with the camera on a tripod in Live View mode, the sensor can be shifted slightly to adjust the composition. As well as making noticeable vertical and horizontal movements, the sensor can be rotated by the user by up to 1° to level the horizon. I find it hard to imagine that a photographer will go to the trouble of using a tripod and almost get the image correctly composed before finalising it by shifting the sensor. Even when a rock or dry-stone wall is used to support the camera, the automatic correction is the easier option.
Pentax K-7 Other features
Pentax’s engineers have clearly put a lot of work into the K-7 and its specification has just about everything we would expect for a DSLR aimed at serious enthusiasts. The Live View system has contrast, phase and face detection AF, and the scene is displayed on the 3in, 920,000-dot LCD screen. There’s even high-definition video technology, which brings the camera into line with the market leaders.
There’s also automatic distortion and lateral chromatic aberration correction (with DA and DFA-series lenses), wireless flash capability and a multiple exposure mode. Although it features dynamic range optimisation settings (highlight and shadow correction), the K-7 is the first DSLR to feature an in-camera high dynamic range (HDR) option that combines three shots to make one composite image.
Image: I found the in-camera level very useful with scenes that have sloping lines like this. The Window is perfectly level. The inset enlargement shows the smudging of detail in the edges of the frame with the new kit lens
Build and handling
Thanks to its stainless-steel alloy frame and magnesium alloy body, the K-7 has a tough, durable feel that is matched by the presence of 77 seals to make it dustproof and weather resistant. I find it an extremely comfortable camera to hold and use. The contours of its grip are almost perfect for my hand, so it feels secure and easy to carry for several hours.
Pentax K-7 Control buttons
There is plenty of direct control via buttons and dials, which are all sensibly arranged and lie within easy reach. While these buttons and rubberised dials have a well-made, dependable feel, I was surprised that the lettering on the Info button had started to rub off by the end of this test.
Although the K-7 has 37 customisation options so that, for example, it is possible to decide which of the two dials is used to select the exposure settings in each of the exposure modes, there is no menu customisation. There is no option to save preferred or frequently used menu options to a separate screen and, frustratingly, there isn’t even an option to make the menu open at the point where it was last used. This can mean quite a bit of navigating through the menu. It’s an oversight that I hope will be addressed with a firmware upgrade.
I would also like a quicker route to the Shake Reduction control, which can only be accessed via the fourth screen of the shooting menu. Ideally, this should be turned off when the camera is used on a tripod, so quick access is an advantage.
Pentax K-7 Image finishing tone
Pentax has given the K-7 an impressive number of ways of varying the look of an image, with the Image Finishing Tone options providing control over the saturation, hue, brightness, contrast and sharpness of colour images. Coloured filter and toning effects can also be applied to monochrome images. Tone adjustments are saved by overwriting the original, but the default settings are easily found again as the marker turns green rather than yellow.
A preferred image tone can also be stored as part of the User settings, which, once saved, is accessed via the main mode dial. This option saves a large number of the camera settings for future recall. It may not always be desirable for the camera to be reset to the user’s default setup, just to use the saved image tone.
Pentax K-7 Control panel
In keeping with many camera manufacturers today, Pentax has provided the K-7 with a control panel that is displayed on the main LCD screen. This panel is made up of two screens that are accessed via the Info button, and it provides a quick means of checking the camera settings and making adjustments.Apart from the lack of menu customisation and a few issues with the viewfinder (see ‘Viewfinder, LCD, Live View and Video’ opposite), the build quality and handling characteristics of the Pentax K-7 are very good.
“There is plenty of direct control via buttons and dials, which are all sensibly arranged and lie within easy reach”
White balance and colour
During the course of this test I encountered the full gamut of British summer weather and the K-7’s automatic white balance system coped with it all very well. Most of my images look good straight from the camera, but a few taken in very overcast conditions look a little magenta, which is easily corrected.
I found that the daylight setting, marked with a sun icon, produces good results in both bright and gloomy conditions. This is likely to have been helped by the fact that I used the option (in the second screen of the custom menu) to set the camera to automatically adjust the white balance within a range when specific settings are selected.
Although the default Image Finishing Tone setting is Bright, I prefer to use the Natural setting as this applies slightly less sharpening and produces more muted images with lower contrast. However, those who want more punchy images direct from the camera may prefer the Bright setting and wish to boost the saturation and contrast levels.
Seven is a very important number for the Pentax K-7 – its body has 77 water resistant seals and its new metering system has 77 segments. The latter appears to contribute towards making the K-7 produce more acceptable exposures in a wider range of situations than the K20D, which is quite heavily skewed towards underexposure.
I found that the K-7 is less prone to underexposure than the K20D, and in several instances it correctly exposed the foreground and allowed quite large, bright areas to burn out. Some may argue that it is better to underexpose a scene to preserve the highlights and then brighten the image on the computer, but many photographers prefer to produce images with their main subject correctly exposed in-camera.
That said, part of this test was conducted in overcast conditions and it was no surprise that the K-7 produced underexposed shots when set to its multi-segment metering mode. These conditions are a challenge to most metering systems.
While the K-7 metering system is an improvement on that of the K20D, it doesn’t throw up any major surprises and it is helpful to have an understanding of how a camera’s meter traditionally responds.
One of the criticisms often levelled at Pentax SLRs is that their autofocus system is slow and noisy. While the SAFOX VIII+ 11-point autofocus system in the K-7 is an improvement upon earlier versions, it struggles with less than perfect targets and the familiar ‘zzz-zzz’ sound of the motor is still present at these times.
In good light, AF adjustments are conducted quickly and surprisingly quietly, considering the noise produced when the lens hunts.
Although the nine cross-type AF points positioned around the centre of the imaging frame can usually be relied upon to find their target even in quite low light, in the very overcast conditions I experienced during some of this test the outer two linear AF points were almost useless. Further testing conducted once the firmware upgrade (V.1.01) was issued suggests that this has been significantly improved. The situation is also much better in brighter weather and with high-contrast subjects.
When set to continuous AF, I found that the K-7 does a reasonable job of keeping track of moving subjects provided one of the central cross-type AF points is selected and the target doesn’t move too quickly. Although it managed to keep up with children bouncing on a Bungee trampoline (elasticated ropes help them bounce higher and descend more slowly), it struggled with the faster, more random movements of swans at close quarters. I think the K-7 is unlikely to be the camera of choice for sports photographers, despite the 5.2fps maximum continuous shooting rate.
As we now expect with new DSLRs, the K-7 has both contrast and phase detection AF in its Live View mode. The contrast detection system is on a par with that used in most other DSLRs. Sharp focus is achieved, but not quickly enough to use it with moving subjects. There’s also a face detection option, which is good at recognising that there is a face in the scene but it’s slow to focus on it.
When set to its movie mode (via the main control dial), the K-7 can only focus automatically before the shutter release button is pressed to start recording. Once video shooting has been started, the focus can only be shifted manually using the lens focus ring. This is generally preferred by experienced videographers, but it may not be so popular with those who are more familiar with small, mass-market video cameras.
This shot, taken using the smc Pentax DFA Macro 50mm f/2.8 lens on the K-7 at ISO 400 and an aperture of f/2.8, has plenty of detail. However, the out-of-focus area bokeh looks rather unnatural, as there appear to be sharp halos or bands around some of the edges of this crocosmia flower
Resolution, noise and sensitivity
As our resolution test images show, the Pentax K-7 is capable of resolving an impressively high level of detail, especially in raw files at the lower sensitivity settings. Simultaneously captured JPEG files are also good.
Kit lenses are rarely perfect, but I was both surprised and disappointed to find that our sample of the new weather-resistant smc Pentax-DA 18-55mm f/3.5-5.6 AL WR lens resulted in images that are noticeably softer than the smc Pentax-DA 18-55mm f/3.5-5.6 AL II optic supplied with the K20D kit. The corners are especially poor and suffer from astigmatism.
Most of my JPEG files benefit from an application of Unsharp Mask, but it cannot resolve the problem of blurring of detail towards the edges of the image. Several of my images have the main subject towards the edge of the frame and they are disappointingly soft.
Noise makes an early appearance in images from the K-7. High-sensitivity images have a lot of chroma noise, but the raw files are sharp. As usual, JPEG files are softer and a little smudgy when the high-sensitivity noise-reduction system is in its default medium setting.
I prefer the sharper, grittier results when no in-camera noise reduction is applied. The noise is fairly evenly distributed and banding isn’t a major issue. I particularly like the images produced with the camera set to its highest expanded sensitivity setting of ISO 6400 when shooting monochrome images.
These images above show sections of images of a resolution chart, still-life scene and a grey card. We show the section of the resolution chart where the camera starts to fail to reproduce the lines separately. The higher the number visible in these images, the better the camera’s detail resolution is at the specified sensitivity setting
The two dynamic range (D-Range) optimisation controls on the K-7 are Highlight Correction and Shadow Correction. When the Highlight Correction option is selected, the lowest available sensitivity setting is raised from ISO 100 to ISO 200. This allows the camera to underexpose to preserve the highlights.
Interestingly, when using this system, it is often possible to give images more than one stop of extra exposure and still not burn out the highlights. This allows the midtones and shadows to be brightened while keeping the highlights. Our lab tests measured the K-7’s default dynamic range at 12.2EV.
However, switching on the highlight correction sees it drop to 10.4EV because of its impact on the darker tones. Setting the shadow correction to the highest of its three settings brightens images and boosts the effective range to 12.5EV.
This graph shows the brightness values recorded by the test camera when it is used to photograph a stepped graduation wedge. The wedge has transmission values in 1⁄2EV steps ranging from 0 to 12EV. The camera’s exposure is set so the 12EV section in the wedge has a brightness value of 255. Software analysis of the image then determines the recorded brightness values of all the other steps and calculates the camera’s dynamic range.
Pentax K-7 Gamut
This graphic indicates that when set to the Adobe RGB colour space and its Bright Image Tone, the K-7 produces JPEG images that almost cover the sRGB gamut and most of the Adobe RGB space. As we often find, the greens of the Adobe RGB space are the biggest challenge, though purple, red and yellow are reproduced.
Viewfinder, LCD, live view and video
This dial is used to select the still shooting mode or set the camera to its video mode. Pressing the shutter release button starts and stops movie recording.
With Pentax DA and DFA-lenses, chromatic aberration and distortion corrections can be applied automatically via this option in the main menu.
All the dials, buttons and controls are sealed against water and dust. This dial has a knurled rubberised finish that is easy to use in damp conditions.
OK and AF
This button confirms setting selections, but it also activates the AF point selection mode when the K-7 is set to the SEL mode. To avoid confusion, a symbol in the viewfinder and on the LCD screen indicates when the AF points can be selected using the four navigation buttons.
The K-7 has a glass pentaprism viewfinder that provides approximately 100% field of view, so all the scene is visible. However, the corners of the K-7 viewfinder are easily obscured by its surround and the eye needs to be kept to the centre of the finder.
This can be tricky when the camera is mounted on a tripod, but fortunately the K-7 has a fully functioning Live View system that displays the scene being composed on the 3in, 920,000-dot (307,000-pixel) LCD screen. This screen provides a good view, and although fixed it has a 170° viewing angle (horizontal and vertical) so the scene can be seen, albeit with foreshortening, when the camera is at a high or low angle. The 10x magnified view is sufficiently detailed to allow precise manual focusing.
During the overcast weather experienced during part of this test, the view through the viewfinder with the smc Pentax-DA 18-55mm f/3.5-5.6 AL WR kit lens mounted was quite gloomy. I also found the viewfinder data difficult to see in bright light and sometimes I had to cup my hand around the eyepiece to see the level indicator.
Pentax was criticised for the poor execution of its Live View system in the K20D, but the company has managed to make quite a leap with the K-7. As well as putting the K-7’s Live View system on a par with those of other manufacturers, it is the first Pentax DSLR to feature HD video recording. This makes Pentax only the third manufacturer to include HD video technology in a DSLR.
There are three video resolutions available at 640×416, 1536×1024 and 1280×720 pixels, with the latter being equivalent to 16:9 high-definition television proportions and all are recorded at 30fps. Although I found that the camera mic produces reasonably clean sound, an external microphone socket is provided to make it easier to record the subject rather than the photographer’s hands on the camera.
Video footage is smooth and detailed, but the wobbling often seen with CMOS-based video cameras when the K-7 is moved rapidly is visible.
With a street price of around £1,190, the Pentax K-7 (RRP £1,199.99) is set to compete with the Canon EOS 50D (RRP £1,189.99), which has a street price of around £810, and the recently announced Nikon D300s (RRP £1,499) that replaces the D300, which can be found for about £1,130.
Image: Canon EOS 50D
Its 14.6-million-effective-pixel count is closer to the 15-million-pixel count of the Canon EOS 50D than the 12-million-pixel Nikon D300s and it is clear that the K-7’s detail resolution is more than a match for the Canon camera. This, combined with the K-7’s relatively low weight and compact size, could make it the camera of choice for keen landscape, still-life and macro photographers. However, anyone with a keen interest in sports photography will be best served by the D300s because of its superior, well-proven AF system.
While the K-7 offers plenty of opportunity to experiment with different filter effects, colour treatments and even in-camera HDR photography, its menu lacks the finesse and customisation of the other two cameras.
Image: Nikon D300s
The Canon EOS 50D and Nikon D300s can be adapted to suit your personal style of photography, but the photographer must adapt to use the K-7. Pentax is to be congratulated on making it very difficult to choose between the three cameras.
There is a lot to like about the Pentax K-7. Most importantly for the majority of enthusiast photographers, it is capable of recording high-quality images and has class-leading detail resolution.
Its body is wonderfully ergonomic and it feels comfortable, solid and dependable, with just about every button and dial being within easy reach. There are also a number of really useful features that are unique to Pentax. I particularly like the built-in level with its ability to automatically correct a sloping horizon, while the in-camera HDR system and digital filters are fun to play with.
Pentax has addressed many of the issues that were raised with the K20D. The Live View system is now fully rounded and of genuine use, there’s video technology, and the metering system, which is so heavily biased towards underexposure with the K20D, has been updated and is much more satisfactory in the K-7.
Unfortunately, the K-7 still has a few niggling little problems. The AF system, though improved, can be noisy and struggles when subject contrast drops. Also, although the viewfinder provides a 100% field of view, it isn’t especially comfortable to use.
In addition, the menu system needs work to bring it up to the standard offered elsewhere and make it quicker to use. Overall, though, my impression of the K-7 is favourable. It feels and performs like a photographer’s camera and several of my concerns could be addressed with a firmware upgrade.
Pentax K-7 – Key features
The K-7 has program, aperture priority, shutter priority and manual exposure modes, plus Pentax’s unique shutter/aperture priority and sensitivity priority modes. In shutter/aperture priority (TAv) mode the photographer selects the shutter speed and aperture combination, leaving the camera to set an appropriate sensitivity value. Conversely, in sensitivity priority (Sv) mode, the user selects the sensitivity setting while the camera takes control of the aperture and shutter speed.
Hyper manual and hyper program
When shooting in manual mode, pressing the green button sets the exposure settings to those recommended by the camera, as in program mode. Meanwhile, when shooting in program mode, the hyper program function allows the user to switch to shutter or aperture priority mode using the dials on the grip rather than the main mode dial.
Pentax’s Shake Reduction (SR) system is compatible with all Pentax lenses including K, KA, KAF, KAF2 and KAF3-mount optics. It can also be used with screw-mount, 645 and 67 system lenses mounted via an adapter. Where there is no electrical connection between the lens and camera, the focal length value can be set manually via the menu.