Digital SLR

A relatively late entrant into the 10-megapixel DSLR category, the new Pentax K10D offers a number of advantages over its competitors, starting with its more robust, body, which has dust and weatherproof sealing. The plastic case is solidly mounted on a metal chassis, which gives added weight to the camera itself. Balance is excellent and the camera-plus-lens is comfortable to hold and operate. Built-in image stabilisation and dust removal on start-up are based on CCD-shift technology.


The red areas mark the position of the weather-resistant seals on the K10D.

The Pentax-developed 'Shake Reduction' (SR) system is integrated into the camera body in a similar way to Sony's A100. It relies on angular velocity sensors to detect camera shake and uses a ball-bearing-mounted oscillator unit with four electromagnets to counteract motion by re-positioning the free-floating image sensor. Like Sony's body-integrated stabilisation, the K10D's SR system works with all lenses and Pentax claims it provides an advantage of between 2.5 and 4.0 stops of shutter speed latitude for hand-held shooting. The higher figure relates to wide-angle lenses.


The internal chassis that supports the Shake Reduction system in the K10D.


The K10D's imager and image stabilisation/dust reduction mounting.

Physically, the K10D looks like the K100D, although slightly larger and more refined in design. Like the K100D it has two LCDs: a rear-mounted, high-resolution 2.5-inch colour monitor for image playback and adjusting camera controls plus a top-mounted monochrome data display. However, its pentaprism viewfinder is brighter than the K100D's, although it still only covers 95% of the sensor's field of view. Like the K100D, all connector sockets lie behind a solid, spring-loaded door. However, only the K10D has locking battery and memory card compartment covers.

Top panel with lens attached.


Rear panel in playback mode without data display. 

Imager
Pentax has revealed little about the CCD sensor used in the K10D beyond stating its dimensions (23.5 x 15.7mm) and its total photosite count (10.75 million). Nor does it disclose much about the Pentax Real Image Engine (PRIME) image processor that is featured in the new camera.  The camera's buffer memory uses DDR2 (Double Data Rate 2) RAM components, allowing it to claim a read/write data transfer rate of 800 MB/sec which, Pentax claims, is 600% faster than SD RAM and 100% faster than conventional DDR memory. The K10D records image files in the standard JPEG format at 3872 x 2592, 3008 x 2000, and 1824 x 1216 pixel resolution onto SD or SDHC memory cards. Raw image files can also be recorded at 3872 x 2592 pixels in Pentax's proprietary PEF.RAW or the open-format DNG file formats. Users must set which of the two raw file formats they want in the Record Mode menu. The highest-resolution JPEG files are just under 5MB in size, while Raw files in both PEF and DNG formats average about 18MB.

A dedicated RAW button is provided for switching to Raw or RAW+JPEG capture. The default setting is for a single shot. To continue shooting in this mode until you press the RAW button again, you must set One-touch RAW+JPEG in the Custom Setting menu. In-camera Raw file processing allows Raw files to be converted into JPEGs with adjustments to image size, quality, white balance, ISO, image tone, saturation, sharpness and contrast. These functions are accessed in Playback mode via the Fn button.

Pentax is the first of the major DSLR manufacturers to offer photographers the choice between proprietary and open Raw file formats and we hope others will follow. The camera is supplied with the SilkyPix, Raw file converter but we suspect most users will prefer to shoot DNG files and convert them with Adobe Camera Raw or Lightroom. 

Shooting Modes
The K10D's mode dial includes a number of new settings in addition to the standard full-auto, shutter- and aperture-priority AE and M settings. The P mode denotes a 'Hyper-Program' that provides program-shift facilities via the control dials. Two control dials are provided, the front one covering shutter speeds and EV compensation while the rear handles aperture and ISO settings.


Mode dial settings.

Pentax has made ISO sensitivity a full user variable by allowing photographers to set an upper and a lower point within which the camera will be free to automatically adjust the ISO setting. Two new modes capitalise on this facility: the 'TAv' mode, which lets photographers set both the aperture and shutter speed while the camera will adjust the ISO setting and a dedicated 'Sv' mode that prioritises ISO settings and enables the camera to adjust other parameters automatically. A warning can be set to display in the viewfinder when the range is exceeded. (Unfortunately, ISO values are not included in the viewfinder display; you must press the OK button on the rear panel to display the current ISO setting.)

Dedicated modes are provided for Bulb (for exposures longer than 30 seconds) and flash exposures (with an X-synch of 1/180 second). (You need the optional CS-205 cable switch to use the Bulb mode.) Finally, there's a 'USER' mode that lets you retrieve exposure combinations you have saves via the Setup menu.  Whenever you switch the camera on or change a mode, a 'Guide display' appears for three seconds on the monitor to clarify the camera settings.

Controls
Rear panel controls include the standard Menu, delete, Info and playback buttons plus a 'Fn' button that accesses the white balance, drive modes, ISO and flash modes in the shooting mode plus Digital Filter, DPOF, slideshow and Raw development settings in playback. The Digital Filter allows JPEG images to be converted to B&W, sepia or a monochrome colour (R, G, B, Y, M or C) in the camera and saved as separate files. You can also apply softening or slimming filters and adjust image brightness through +/- eight levels in this mode. A special Raw development setting lets you convert Raw files into JPEGs and provides adjustments for image size, quality, tone, contrast, sharpness, saturation and sensitivity. It's an alternative way of RAW+JPEG recording.

Pressing the AF button and rotating the collar around the arrow pad lets you select the AF point. Three options are provided: auto, centre and manual selection. The K10D's 11-point AF system was fast and accurate in normal lighting. So was the16-segment metering system and photographers can opt for centre-weighted or spot metering by adjusting a level beneath the mode dial. An exposure bracketing button lies left of the viewfinder eyepiece, with the standard Pentax 'green button' near the shutter release for re-setting exposure values in the P, Sv, Tv and Av modes and adjusting exposures in M mode.

White balance controls are extensive and include a default auto setting plus six pre-sets covering common lighting situations (including daylight, shade, fluorescent and incandescent lighting and flash). Manual measurement and adjustment is also provided, along with a colour temperature setting that provides adjustments in Kelvin (the default) or Mired values. Settings can be fine-tuned along two axes: green/magenta and blue/amber. Adjustments are accessed via the Fn button and the arrow pad is used to change settings. Three colour temperature settings can be saved in the camera's memory.


White balance adjustments.

The basic colour tone of images can also be adjusted via the Image Tone setting which gives users the choice of Natural or Bright settings. Natural is recommended for shots that will be edited, while Bright produces shots with enhanced brightness and contrast for direct printing. In-camera adjustments are also provided for saturation, sharpness and contrast with +/-3 levels for each parameter. None of these controls affect Raw image files.

The K10D includes two preview functions. The Optical preview, which replicates a depth-of-field preview function, is accessed by pressing the shutter button half way and pushing the main on/off switch to the right. No shooting information can be displayed in this mode. The Digital preview allows you to make a temporary recording of the preview image in Optical preview mode. The image is held for 60 seconds, during which time you can view the histogram or exposure warnings and apply playback zoom.

The Custom settings menu is extensive and contains 34 settings including an innovative Program Line with four options: Normal, Hi-Speed, Depth and MTF. It works in the 'Green' and Program shooting modes, where the camera sets shutter speed and aperture plus ISO, if you wish. Selecting the Hi-Speed line prioritises high shutter speeds, while the Depth setting selects smaller apertures to maximise depth of field. The MTF setting selects the aperture settings for the attached lens that achieve the highest resolution. It works best with DA, DFA, FA and FAJ lenses.

The built-in flash has a Guide Number of 11 at 100 ISO and can be used with lenses no wider than 18mm (28mm in 35mm format). It has the usual mode, including slow-speed, front curtain and rear curtain synch. It is most effective at distances between 0.7 and 4 metres from the lens. Closer subjects could be over-exposed and vignetting may occur with certain lenses. In the P mode, the flash can be used for backlight compensation but flash output adjustment is not provided, one of the few omissions from this camera.

Unlike other Pentax DSLRs, the K10D is powered by a rechargeable lithium-ion battery, which claims to support roughly 500 shots without flash or 480 shots with 50% flash usage. Playback usage time is approximately 330 minutes. A single charge still left plenty of power in reserve at the end of our tests. A battery grip, the D-BG2, is available optionally. As well as doubling power capacity it also includes a vertical shutter-release button, preview lever, two control dials, AE-lock button and green button.

 The K10D with the D-BG2 battery grip attached.

Performance
Our tests were done with two lenses: the smc Pentax DA 1:4 16-45mm ED-AL and the Sigma DC 17-70mm 1:2.8-4.5. With both lenses, the K10D delivered images with bright colours and plenty of detail plus no evidence of over-sharpening. Both types of Raw files were able to accommodate extended-brightness-range subjects and were easy to adjust in Adobe Camera Raw, which users will appreciate. Image noise levels were generally low and the resulting files were clean. A

t ISO 800 noise became visible but here, and at ISO 1600 it was no worse than in competing cameras - and less obvious than some models. Noise reduction processing is applied by default for exposures longer than a second. It doubles file processing times but can be switched off by the Custom menu.

Imatest showed the K10D to be capable of high resolution but we found some interesting differences in performance between the two lenses that were supplied. The Pentax lens delivered slightly higher resolution, while the Sigma lens had less lateral chromatic aberration. We found noticeable purple/green fringing at the edges of shots taken in bright conditions with both lenses (see samples below). Both lenses also exhibited declining sharpness towards the edges of shots, with the Sigma lens showing more edge softening than the Pentax lens.


Purple/green fringing with the Pentax lens.


Purple/green fringing with the Sigma lens.


Reference image to show the degree of enlargement required to make the above fringing obvious.

Colour accuracy was very good under most available light conditions, especially for outdoor shots. However, white balance performance was not particularly impressive as the auto setting was unable to achieve total neutrality with either incandescent or fluorescent light. Better performance was delivered by the relevant pre-sets and close to neutral colours with the manual measurement function. Long exposures at night were relatively free of colour noise up to ISO 400 and it was relatively low thereafter, although we spotted a few stuck pixels in some shots taken without noise reduction enabled.


Auto white balance under fluorescent lighting.


Auto white balance with incandescent lighting.

Flash performance was as good as you would expect from the built-in flash on a DSLR. Coverage was even and colours were reproduced with good neutrality.

It took just over half a second to power-up the camera and take a picture and approximately 1.5 seconds to see the resulting shot. Image playback was almost instantaneous. The continuous shooting mode recorded 9 RAW+JPEG images at 3 fps then slowed to one frame/second. JPEG files can be recorded at 3 fps to card capacity with a fast card, although capture rates slowed to 2 fps after about 30 shots. It took just over 5 seconds to clear the buffer memory with JPEG capture and around 8 seconds with RAW+JPEG.

IMATEST RESULTS

SAMPLE IMAGES

Close-up.


Pentax lens dynamic range.


Sigma lens dynamic range.

Image sensor: 23.5 x 15.7 mm Interline Interlace CCD with primary colour filter; 10.75 megapixel – total; 10.2 Megapixel – effective
Lens mount: KAF bayonet, compatible with
KAF2-, KAF-, KA- lens mounts, KAF power zoom function available, K- lens mounts with restrictions, M42 and medium format lenses with adapter subject to restrictions with exposure metering and control
Focal length crop factor: 1.5x
Image formats: PEF and DNG RAW, 3 x 12 bit (internal 3 x 22 bit); JPEG (Exif 2.21, 3 x 8 bit in JPEG)
Image Sizes: 3872 x 2592, 3008 x 2000, 1824 x 1216; 3 compression levels: Best (1/3), Better (1/6), Good (1/12)
Shutter speed range: 1/4,000 to 30 sec.
Self-timer: 12 or 2sec. (with mirror lock up)
Image Stabilisation: CCD-shift Opto-mechanical sensor with “Shake Reduction” function
Dust removal: Anti-dust coating on low pass filter plus CCD vibration
Exposure Compensation: ±2EV (1/3 or 1/2EV steps)
Focus system: TTL Phase Matching with 11 focus points (SAFOX VIII) with viewfinder indications
Focus modes: Automatic and manual focus point selection, spot focus. Support for lenses with supersonic focusing motors. Manual focus
Exposure metering/control: TTL open-aperture 16-segment metering coupled with lens and AF information, adjustable between multi-segment, center-weighted and spot metering. Metering range 0 – 21 EV (at Standard Output Sensitivity 100 with 50mm f/1.4 lens); Program (Green Mode), Hyper Program, Sensitivity Priority, Shutter Priority, Aperture Priority, Shutter and Aperture Priority, Manual (Hyper Manual), Bulb, X-sync
Custom functions: 32
ISO range: Auto, ISO 100 – 1,600 in 1/3 EV or 1/2 EV steps
White balance: Automatic or manual, Daylight, Shade, Cloudy, Tungsten light, Fluorescent light (W, D, N), Flash, manual balance, 3 different settings for Kelvin and Mired values with fine adjustments
Flash: Built-in P-TTL Automatic Flash with automatic operation in low light conditions, Guide number 15.6 at ISO 200, flash coverage 28mm (35mm equivalent) hotshoe on camera top for system flash, flash sync 1/180sec.
Sequence shooting: 3fps unlimited JPEG or 9 RAW images, Auto Bracketing 3 or 5 frames
Storage Media: Secure Digital card, SDHC card compatible
Viewfinder: Built-in pentaprism finder with a 95% field of view and 0.95x magnification (with 50mm F1.4 lens, infinity, -1m–1), with interchangeable “Natural Bright Matt II” focusing screen. Diopter correction –2.5 – +1 dpt.
LCD monitor: 2.5-inch low-temperature polysilicon TFT colour LCD Monitor with 210,000 pixels, brightness control and wide viewing angle (approx. 140°), single image review with 20x magnification, Hot Spot indicator and Histogram display with RGB channel indicators (also in Preview function), auto image rotation for viewing
PC interface: USB 2.0
Power supply: Rechargeable Li-Ion battery D-Li50 for approx. 500 exposures, Battery Grip D-BG2 for D-Li50 with vertical shutter release, AC mains adapter (available optionally)
Dimensions (wxhxd): 141.5 x 101 x 70 mm (body only)
Weight: 710 grams (body only without battery and card)