Digital SLR

Pentax has used many features from last year's K200D as the basis of its new K-m DSLR. The sensors, viewfinders and LCD screens in both cameras are the same. However, the K-m is pitched more at first-time DSLR owners. It's as easy to use as an advanced digicam and offers some novel functions - including a swag of digital filters. But some features have been downgraded from its predecessor.

The review camera was supplied to us as a twin lens kit, with the smc Pentax-DA 18-55mm f/3.5-5.6 AL and smc Pentax-DA L 50-200mm f/4-5.6 ED lenses. Reviews of these lenses can be found on the Photo Review website.

The new model's body lacks the K200D's weatherproof sealing and its AF system has only five sensors, instead of 11. However, the wide-area SAFOX VIII AF system uses five cross-type sensors, which are more accurate than linear sensors.  Individual focus point selection is replaced by choosing between wide (the default) and spot focusing areas. The flash is also less powerful, with a guide number of 11 (instead of 13). Live view shooting is not supported but, like its predecessor, the K-m includes a digital preview function. 

The market for 10-megapixel DSLRs is very competitive, with all leading manufacturers vying for market share. The K-m is the highest priced in the current crop and also the second heaviest. But it's the only one to support the 'universal' DNG.RAW file format and boasts the largest number of Custom functions. Click here to view a comparison table.

Size, it seems, matters in this market sector and, although neither the smallest nor lightest model on sale, dimensionally the K-m is significantly smaller and 105 grams lighter than the K200D. It's not as small as the Olympus E-420 but outclasses Nikon's D60 and Canon's EOS 1000D in 'petite-ness'. Reducing the K-m's body size was made possible by the development of a compact, lightweight and high-rigidity stainless-steel chassis, downsizing Shake Reduction mechanism and circuit boards and use of the latest high-density packaging technologies. The battery compartment has also been repositioned, enabling the camera grip to be redesigned to provide a secure hold of the camera body. Switching between auto and manual focus is handled by a slider on the left side of the lens mount.

Front view of the Pentax K-m fitted with the 18-55mm kit lens.

The K-m's grip is deep and relatively narrow. It's comfortable for average-sized hands and shouldn't daunt potential buyers with small hands. However, anyone with large hands or thick fingers could find it cramping. Simple, easy-to-operate controls are a key selling point in this market sector and the new model's control layout has been simplified to make it more competitive and user-friendly to first DSLR buyers. 


Rear view showing the simplified button layout and new graphic interface.

All button controls are now located to the right of the LCD screen and, aside from the arrow pad, there are only four of them: Play, Info, Menu and Delete. Directly above the Play button is an 'e-dial' for adjusting aperture, shutter speed, sensitivity and EV compensation settings.

An AF button on the top right corner of the rear panel can be used to lock the focus or, alternatively, re-programmed to work as an AE lock and memorise the exposure value for a selected area. On the opposite side of the rear panel is another button for raising the pop-up flash.

The viewfinder on the K-m isn't quite as bright as we'd like and covers only 96-percent of the sensor's field of view with roughly 0.85-times magnification. A slider on the top of the housing provides easy diopter adjustment and the eyecup surround is made from soft rubber that doesn't damage glasses. Superimposed on the image is the AF frame with indicators showing the five sensor points (simulated below).

Status indicators showing the flash status, shooting mode, shake reduction, shutter speed, aperture, focus indicator and number of recordable images are shown below the image. ISO sensitivity can be displayed by pressing the OK button and the focus mode is displayed when manual focus is selected. EV compensation can be adjusted without taking your eye from the viewfinder by pressing the +/-AV button and rotating the e-dial.

The simplified user interface design presents status information graphically, using similar styling to other manufacturers' entry-level DSLRs. When you first turn the camera on the monitor briefly displays a screen indicating the selected shooting mode plus the current date and time. After a second or so this switches to the data panel display, which shows the shooting mode, aperture and shutter speed settings, exposure compensation and frame number.

Pressing the OK button on the arrow pad opens direct access to the settings in the lower half of the display. The arrow pad buttons are used to navigate from one adjustment parameter to the next while turning the e-dial changes settings within the selected parameter.


Sensitivity adjustments in one of the sub-menus. Turning the e-dial changes the settings.

The top panel carries a large mode dial with 13 Capture Mode settings. These are split between the Picture mode, which has pre-sets for Auto Picture, Portrait, Landscape, Macro, Moving Object, Night Scene Portrait and Flash Off, and the Exposure mode, which carries the P (Program AE), Sv (Sensitivity Priority), Tv (Shutter Priority), Av (Aperture  Priority) and M modes. Between them is a Scene mode that accesses a sub-menu containing pre-sets for Night Scene, Surf & Snow, Food, Sunset, Stage Lighting, Kids, Pets, Candlelight, Museum and Night Snap modes.


Top view showing the mode dial and exposure compensation and Help buttons.

Aside from the shutter button, only two other buttons are provided on the top panel: the AV +/- and Help buttons. The former sets exposure compensation in modes where it is supported and is used to change aperture values in Manual mode. Pressing the Help button displays details of the selected shooting mode. Pressing it a second time lets you select a function you want explained. A third press exits the help screen.


Pressing the Help button displays information about the selected shooting mode.

Pressing it a second time lets you select a function you want explained.

The Auto Picture mode is similar to the K200D's and includes some 'intelligent' scene selection processing. The camera is pre-programmed to identify five Picture mode settings (Portrait, Landscape, Macro, Moving Object and Night Scene Portrait) and will automatically set exposure parameters to match these scene types. When no match is available, it defaults to normal auto exposure.


The Auto Picture setting can recognise five pre-set subject types and will set camera controls accordingly.

Selecting a particular Scene mode displays a sample image followined by an explanation of how the setting should be used.


Settings provided in the Scene mode sub-menu.

ISO sensitivity has been extended from a top of 1600 in the K200D to 3200 in the K-m. Continuous shooting is also faster at 3.5 frames/second with a higher buffer capacity of four raw files or five JPEGs. Both cameras include Pentax's excellent SR (Shake Reduction), which uses magnetic forces to move the image sensor vertically and horizontally to counteract the amount of camera shake detected by a built-in sensor.  This system claims to offer up to four f-stops of compensation.

Pressing the Menu button on the rear panel accesses a fairly standard menu system with three pages of Shooting settings, two pages for Playback, a three-page setup menu and four pages of Custom functions. Some interesting adjustments can be found in these pages for users who shoot JPEGs. (No in-camera processing is applied to raw files when they are captured, although some post-capture processing can be applied (see Playback below.)

Sensor and Image Processing
The sensor used in the K-m appears to be the same chip as used in the K200D - and also the Nikon D60 and Sony A200 models. Manufactured by Sony, it offers an effective resolution of 10.2 megapixels, which will enable users of this camera to print their images up to A3+ size with ease. Coupled with the sensor is the PRIME (Pentax Real Image Engine) image processor, which is responsible for the many function sophistications the camera offers.
Image size options are essentially the same as in the K200D. Both cameras offer a choice of the Pentax proprietary PEF and 'open' DNG raw file formats plus three JPEG sizes and compression ratios. Raw files are only recorded at full image size and RAW+JPEG capture is supported for both raw file formats. Typical file sizes are shown in the table below.

As well as expanding ISO sensitivity to 3200, the PRIME processor also provides a dynamic-range expansion function that enables users minimise the risk of blown-out highlights and blocked-up shadows in shots taken in contrasty lighting. This type of processing is increasingly common in DSLR cameras at all levels and is particularly useful in Australian conditions.

Like many DSLR cameras, the K-m provides two noise reduction processing settings, separately covering slow shutter speeds (long exposures) and high ISO settings. Both settings are found in the Custom Function menu and the default settings are on for the former and off for the latter. Slow shutter speed NR processing can only be switched on and off but high ISO NR processing offers four levels: off, weakest, weak and strong.

The first page of the Shooting menu carries a Custom Image setting that lets you choose from six Image Tone modes: Bright, Natural, Portrait, Landscape, Vibrant and Monochrome, all involving some degree of image processing. They're largely self-explanatory and usable only in the Exposure modes (P, Tv, Av, Sv and M) - but only for JPEG capture. Each Custom Image setting is individually adjustable for the following parameters: saturation, hue, contrast, sharpness, toning and filter effects.

Just below the Custom Image setting lies the Digital Filter setting. Six effects are now available, again only for JPEG capture. These settings simulate a range of novel effects and provide the adjustments shown in the table below.

Other Functions
Most of the remaining camera functions are pretty standard. However, in addition to the standard suite of white balance pre-sets plus manual white balance measurement, the K-m includes an Adjust White Balance function that provides seven levels of adjustment across green/magenta and blue/amber colour axes. This function must be enabled in the Custom menu (Custom setting 2) before it is usable.

The final page of the Setup menu carries six items: Pixel Mapping, Dust Alert, Dust Removal, Sensor Cleaning and Format. Pixel Mapping causes the camera to identify any defective photosites on the CCD and applies automatic interpolation to correct these deficiencies.

The Dust Alert, Dust Removal and Sensor Cleaning functions operate with the built-in CCD-shift dust prevention system that is coupled to the SR system described above. The low-pass filter in front of the image sensor is coated with a fluorine compound that is designed to prevent dust from adhering to the filter. Vibration of the filter on start-up dislodges residual dust, which falls onto an adhesive sheet positioned at the bottom of the SR unit.

When dust fails to be dislodged with vibration, selecting the Dust Alert function in the setup menu allows you to photograph a uniformly white subject. An image showing the location of dust spots is saved in the camera. This image can be used to clean off stuck-on dust that can't be removed with the normal Dust Removal function.
Dust Removal is also located in the setup menu and lets you choose when the sensor vibration system engages. The default setting is to turn it on each time the camera is powered up. However, you can engage it manually, if required.  Selecting Sensor Cleaning locks up the reflex mirror, exposing the sensor surface for cleaning. The Format setting is used to delete all data on the camera's memory card.

Playback
Playback functions are pretty standard and include the normal single, index and zoom options. Index thumbnails can be displayed four, nine or 16 to a screen. A scroll bar along the right side of the screen enables users to jump backwards and forwards to adjacent sets of thumbnails. Calendar and Folder displays are also provided and pressing the Info button displays shooting data with selected images.

Playback menu options.

The e-dial can be used to enlarge displayed images ranges up to 16x or reduce them to 0.75 times their full-screen display size (although we can't think when this would be useful). Image Rotation is also supported. You can join several images together in Playback mode and display them as an index print, which can be saved separately.

Side-by-side comparison of two shots is also supported, along with slideshow playback of images on the memory card. Intervals between images can be set to three, five, 10 or 30 seconds in slideshow mode and fade, wipe and zoom transitions can be included.

Images can be deleted individually or groups of shots can be selected for deletion.  Folders can also be deleted. Individual shots can be protected against accidental deletion and tagged with DPOF settings for automated printing. JPEG images can be resized in the camera, with both the resolution and JPEG compression separately adjustable. They can also be cropped to one of seven pre-set sizes and you can control composition by moving the cropping frame with the arrow pad.

Histograms and Bright/Dark area displays can only be viewed in Playback mode and they must first be switched on via the Instant Review setting on page 2 of the shooting menu. The histogram shows brightness only but it's large enough for quick exposure assessments.

The Digital Filter effects provided in the Shooting menu are also available for post-capture processing in the camera, where an additional eight effects are provided:

Raw files recorded with the camera can be 'developed' in the camera in playback mode. They can only be converted into JPEGs but you can specify three output sizes and quality levels, apply Custom Image processing, adjust white balance and sensitivity (but only across a range of -2.0 to +2.0) and apply High ISO noise reduction processing. Shadow compensation can be turned on or off and you can choose between sRGB and Adobe RGB colour space settings. 

Software
The K-m is supplied with Pentax PHOTO Laboratory 3 raw data processing software and Pentax PHOTO Browser 3 browser software. However, since no software was supplied with the review camera, we can make no further comments. 

Performance
Pictures taken with the test camera were acceptably sharp and had natural-looking colours and the dynamic range depth we've come to expect from current DSLRs. Colour accuracy ws very good in our Imatest tests. Contrast and saturation in test shots were more restrained than we've seen with some entry-level DSLRs we've reviewed, giving plenty of scope for further adjustments.

Focusing was generally fast and, in most cases, accurate with both test lenses, although it slowed a little in low light levels. We also had few problems with the K-m's metering system, whatever  mode we selected.

The body-integrated image stabiliser also proved effective, enabling us to shoot with shutter speeds a couple of f-stops slower than would have been possible with a non-stabilised camera. Unfortunately, the test camera proved a little power-hungry, running through a fully-charged set of new NiMH rechargeables in just over 100 shots.

Overall image quality was generally good and Imatest confirmed that the camera was capable of the resolution expected for a 10-megapixel camera at ISO 100. Interestingly, DNG.raw files converted with Imatest gave slightly lower resolution than the JPEG files shot at the same time.

Resolution declined gradually as ISO sensitivity was increased, although the loss of resolution at ISO 3200 was less than we expected. The graph below shows the results of our Imatest tests.

Test shots taken in dim lighting with and without flash showed little visible noise right up to ISO 800. Stepping up to ISO 1600 produced a noticeable increase in granularity and some blotchiness was evident in the darker areas of the picture. By ISO 3200, both colour and pattern noise were visible and shots were visibly blotchy. Switching on high ISO noise reduction processing reduced some of the grain and blotchiness with only a slight decrease in image sharpness.

Auto white balance was comparatively good for an entry-level DSLR, although traces of green remained in shots taken under fluorescent lighting and shots taken in incandescent lighting retained their orange cast. However, both pre-sets came close to neutral colour rendition and with adequate scope for in-camera tweaking of colour balance, this issue is largely irrelevant for serious photographers.

Flash performance was generally very good and the built-in flash provided even illumination of an average-sized room throughout the camera's ISO range. Flash exposures were also well balanced for indoor close-ups for which flash provided the main illumination.

Camera response times were in line with competing DSLRs. The review camera powered-up in less than a second and we measured an average capture lag of 0.15 seconds, which reduced to less than 0.1 seconds with pre-focusing. It took 1.5 seconds on average to process each JPEG image and 2.6 for each raw file. A RAW+JPEG pair took approximately 4.5 seconds to process.

The continuous shooting mode performed to specifications, capturing 12 Large/Fine JPEGs in 5.2 seconds, with capture speed slowing after seven shots. Five DNG.RAW files were recorded in 1.3 seconds in burst mode. It took 12.1 seconds to process the JPEGs and 10.4 seconds to process the raw files. With RAW+JPEG capture, the review camera recorded four image pairs in one second. It took 11.3 seconds to process this burst.

Buy this camera if:
- You're seeking a capable DSLR with a straightforward user interface and plenty of creative filter effects for in-camera image processing.
- You want a DSLR camera that produced natural-looking hues and tones in JPEG files straight from the camera.
- You're interested in capturing and adjusting raw files.
- You'd prefer to use AA batteries.

Don't buy this camera if:
- You need a pocketable camera.
- You plan to leave the camera on full-auto for all shots.
- You want live view shooting.
- You want face detection.
- You'd like a wide choice of lenses (Pentax's range is currently smaller than competing brands). 

IMATEST GRAPHS

JPEG image files

Raw image files converted into 16-bit TIFF format with Imatest.

SAMPLE IMAGES

Auto white balance with incandescent lighting.

Auto white balance with fluorescent lighting.

30-second exposure at f/4.5; ISO 100.

13-second exposure at f/14; ISO 3200.

Flash exposure, ISO 100

Flash exposure, ISO 3200

Close-up: 50mm focal length, ISO 100, 1/20 second at f/5.6.

35mm focal length, ISO 100, 1/90 secondat f/6.7.

35mm focal length, ISO 100, 1/30 second at f/9.5.

55mm focal length, ISO 100, 1/40 second at f/11.

55mm focal length, ISO 400, 1/1000 second at f/8.

50mm focal length, ISO 400, 1/250 second at f/8.

50mm focal length, ISO 100, 1/90 at f/4.5 (note slight vignetting). 

Additional sample images can be found in the reviews of the smc Pentax-DA 18-55mm f/3.5-5.6 AL and smc Pentax-DA L 50-200mm f/4-5.6 ED lenses. 

Image sensor: 23.5 x 15.7 mm Interline interlace CCD with 10.75 million photosites (10.2 megapixels effective)
Lens mount: Pentax KAF2 bayonet mount
Focal length crop factor: 1.5x
Image formats: JPEG (8-bit, Exif 2.21), PEF/DNG Raw (12-bit); RAW+JPEG available
Image Sizes: 3872 x 2592, 3008 x 2000, 1824 x 1216 pixels
Image Stabilisation: Image sensor shift mechanism, Max 4 stops
Dust removal: Image sensor vibration and SP coating with Dust Alert
Shutter speed range: 30 to 1/4000 second plus Bulb
Exposure Compensation: +/-2 EV (0.5EV steps or 0.3EV steps)
Exposure bracketing: 3 frames within range of +/-0.5EV, +/-1.0EV, +/-1.5EV (0.5EV steps) or +/-0.3EV, +/-0.7EV, +/-1.0EV (0.3EV steps)
Self-timer: 12 or 2 seconds delay
Focus system: TTL Phase-matching 5-point wide autofocus system (SAFOX)
Focus modes: AF.A (auto), AF.S (single, with focus lock), AF-C (continuous), Manual focus; AF-Assist lamp via built-in flash
Exposure metering: TTL open-aperture 16-segment metering (coupled with lens and AF information); multi-segment, centre-weighted and spot modes
Shooting modes: Auto Picture mode, Picture mode, Scene mode, Program AE, Sensitivity-Priority AE, Shutter-Priority AE, Aperture-Priority AE, Metered Manual, Bulb
Picture Style/Control settings: Digital Filter: Toy camera, High contrast, Soft, Star burst, Retro, Extract colour
Colour space options: sRGB, Adobe RGB
Custom functions: 21
ISO range: Auto, Manual: 100~3200 (1EV steps or 1/2EV steps or 1/3EV steps); Bulb mode: up to ISO1600
White balance: Auto, Daylight, Shade, Cloudy, Tungsten, Fluorescent (W, D, N), Flash, Manual setting, with WB fine adjustment
Flash: Built-in retractable P-TTL auto pop-up flash; GN approx. 11; x-synch at 1/180 sec.
Flash exposure adjustment:
Sequence shooting: Max. approx. 3.5fps for 5 frames (JPEG and Continuous Hi) or 4 frames (RAW); approx. 1.1fps to card capacity (JPEG and Continuous Lo)  or for 7 frames (RAW)
Storage Media: SD/SDHC memory cards
Viewfinder:  Fixed moulded penta-mirror with Natural-Bright-Matte II focusing screen; approx. 96% field of view; magnification 0.85x (50mm f/1.4 lens at infinity); dioptre adjustment -2.5 to +1.5 dpt.
LCD monitor: 2.7-inch TFT colour LCD with 230,000 dots; brightness adjustable; wide angle view
Live View modes: Digital preview only
Video Capture: No
Data LCD: No
Playback functions: One Image, Index (4, 9 or 16 thumbnails), Enlargement (up to 16x, scroll available), Image Rotation, Folder view, Slideshow, Histogram, Bright/Dark area, Resize, Trimming
Interface terminals: USB2.0 (HI-Speed)/Video (PAL/NTSC)
Power supply: Four AA (lithium, alkaline, and rechargeable Ni-MH) batteries; rated for 1650 shots without flash; 1000 with 50% flash
Dimensions (wxhxd): 122.5 x 91.5  x 67.5 mm
Weight: approx. 525g without battery and SD memory card