Digital SLR

Nikon's successful entry-level D40 DSLR has been given an upgrade in the new D40X by replacing the 6-megapixel CCD with a 10.2-megapixel imager, similar to the chip used in the D80 model. The new camera is identical to the D40 in all but a few areas and shares its position as the smallest and most compact DSLR cameras in Nikon's range (although the D40's body is20 grams lighter). The bundled kit lens is the same 18-55mm, F3.5-F5.5 AF-S Nikkor as you get with the D40.

Although the image sensor has higher resolution, its dimensions remain the same as in the D40, which means the actual photosites are considerably smaller (6.1 microns squared on the D40X compared with 7.88 microns squared). While the D40X's higher resolution output should be able to record more detail, the smaller, more densely packed photosites are more likely to be affected by noise. Consequently, there's a risk of noise-removal processing (which we found to be quite heavy) further reducing image quality from photosites with less light-capturing ability.

When comparing the D40X to other DSLR cameras, it's useful to reflect on the plusses and minuses of the D40. The construction and functionality of both cameras is excellent, as are the menu system, control layout and user interface options. Few consumer DSLRs can match the two Nikons in these respects. However, because there's no data LCD, the monitor on both cameras must be used for setting up and replaying shots and a fair amount of toggling with the menu, info and arrow pad buttons is required to adjust many camera settings.

Many settings provide illustrations and a brief text explanation of how the function is applied, making this a good camera for learning the finer points of picture-taking. However, simple tasks like adjusting exposure compensation, apertures and shutter speeds require users to hold down one of the buttons behind the shutter release and, at the same time rotate the single command dial. Some digital gymnastics are involved.


The D-Lighting function provides fill-in lighting for backlit pictures.

You can program the Function (Fn) button above the lens release to access one setting (but only one) and hitting the zoom button takes you to a lot of other exposure controls but few dedicated buttons are provided. The new camera offers a one-stop wider sensitivity range that starts at ISO 100 (instead of 200 on the D40) but both cameras top out at ISO 1600 and have a HI-1 setting that reaches ISO 3200. You can still set the maximum sensitivity and minimum shutter speed for the Auto ISO mode via the Custom menu.

Like the D40, the new camera has no internal focusing motor. Consequently, only AF-S and AF-I lenses can be used with autofocusing; all other lenses will be manual focus only. Similarly, some of the metering options will only work with Nikon's AF-S and AF-I lenses, which is bad news for potential purchaser with a suite of older Nikkors they wish to keep on using.

Other missing features include a depth of field preview button and exposure and white balance bracketing, although you do get exposure compensation of ±5 EV in increments of 1/3 EV and flash output adjustment from -3.0 to +1.0 in similar increments. Improvements in power management have allowed Nikon to extend the number of shots per charge from 470 to 520 on the D40X, although the battery itself is the same as in the D40.

Continuous shooting speed is also slightly higher on the D40X at 3.0 frames/second compared with the D40's 2.5 fps. However the 3 fps frame rate can only be achieved when noise reduction processing has been turned off. One compromise made with the shift to the higher-resolution sensor has been a halving of the flash synch speed on the new model. Whereas the D40 supported flash synch at 1/500 second, like the D80, the D40X is restricted to 1/200 second. This can make it difficult to freeze sports action and may limit photographers' options for using flash fill in bright outdoor lighting.

Although no Nikon DSLR has yet provided vibration-based dust removal or CCD-shift image stabilisation, the D40X includes a Dust-off Reference Photo function in the set-up menu that allows users to shoot a reference image of a white target and store the record of any dust on the image sensor. Unfortunately, the dust can only be removed when images are processed with in Nikon's Capture NX software, which is priced at around $240.  

Performance
Imatest showed some interesting differences between shots taken with the test camera in NEF-RAW and JPEG formats. When the raw files were processed by Imatest prior to evaluation, the resulting TIFF files had very low saturation levels, when compared with the punchier JPEG files. The various Optimise Image settings also produced different results with Imatest's colour tests, with the 'Softer' setting delivering dramatically lower saturation than the Normal and Portrait settings and the Vivid setting producing higher saturation levels.

Best overall performance was with the Portrait mode, where the D40X delivered the most accurate colours and highest resolution. With other modes, colour accuracy was slightly lower than the D40 in Imatest tests although the effect on actual photographs was negligible. At 1585 line widths/pixel height, the D40X's MTF50 resolution was not hugely better than the D40 (with 1430 line widths/pixel height), revealing there is little benefit from the higher-resolution sensor. As with the Coolpix P5000, a fair amount of undersharpening processing was applied. This may account for the lower-than-expected MTF50 figures.

Interestingly, despite its smaller photosites, no resolution was sacrificed as ISO sensitivities increased on the newer camera. Lateral chromatic aberration was also slightly lower with the D40X. Long exposures taken at night also yielded some excellent results and little image noise was discernible at ISO settings up to 1600.

White balance performance was similar to the D40. Colour casts were only removed with the pre-set measurements mode. The flash required ISO 400 sensitivity to illuminate an average-sized room but spread its light evenly across the field of view of the lens at the 18mm setting.

The test camera powered up in less than half a second and we measured an average capture lag of 0.2 seconds, which reduced to instantaneous capture with pre-focusing. However, it took almost five seconds to process and store a JPEG image. The continuous shooting mode recorded 4.5MB high-resolution JPEG images at a whisker over 3 frames/second for as long as the shutter was held down. NEF-RAW files averaging just under 11MB in size were captured at the same speed as JPEGs but the buffer could only store six images and it took just over 41 seconds to process six raw files. 

Conclusion
Potential buyers must decide for themselves whether they really need 10-megapixel resolution from their DSLR because, in terms of image quality, there's little to choose between the D40 and the D40X. Both cameras are better suited to users with small hands and both cameras would be an excellent choice for photographers upgrading from a digicam to a DSLR. But, if you've a suite of older Nikkor lenses you wish to keep using, neither of these cameras is suitable; you'd be better off with a D70s or D80.

IMATEST GRAPHS

Raw files converted to TIFFs in Imatest showed dramatically reduced saturation.

Best results were obtained with the Portrait setting.

The Vivid setting produced dramatically increased saturation.

SAMPLE IMAGES

Close-ups.

Auto white balance with fluorescent lighting.

Auto white balance with incandescent lighting.

ISO 100

ISO 1600

Long exposure at ISO 1600.

Centre crop of the above reference image.

Corner crop.

Skin tones.

Scene.

Image sensor: 23.7 x 15.6 mm RGB CCD with 10.75 million photosites (10.2 megapixels effective)
Lens mount: Nikon F mount with AF coupling and contacts (full support for Type G, D AF Nikkor lenses, AF-S and AF-I lenses)
Focal length crop factor: 1.5x
Image formats: Compressed NEF (RAW): 12-bit compression, JPEG: JPEG baseline compliant (Exif 2.21)
Image Sizes: 3,872 x 2,592 [L], 2,896 x 1,944 [M], 1,936 x 1,296 [S]
Shutter speed range: 30 to 1/4000 seconds in steps of 1/3 plus Bulb
Self-timer: Electronically controlled timer with duration of 2, 5, 10 or 20 s.
Image Stabilisation: n.a.
Dust removal: Anti-dust coating on low pass filter plus Dust Off reference photo function
Exposure Compensation: ±5 EV in increments of 1/3 EV
Focus system: TTL phase detection by Nikon Multi-CAM530 autofocus module with AF-assist (range approximately 0.5-3.0m/1ft. 8in.-9ft. 10in.); Detection range: -1 to +19 EV (ISO 100 at 20°C/68°F)
Focus modes: 1) Autofocus (AF): Instant single-servo AF (AF-S); continuous servo AF (AF-C); auto AF-S/AF-C selection (AF-A); predictive focus tracking automatically activated according to subject status, 2) Manual focus (M)
Exposure metering/control: TTL full-aperture exposure metering system; 1) 3D Color Matrix Metering II (type G and D lenses); Color Matrix Metering II (other CPU lenses); metering performed by 420-segment RGB sensor; 2) Center-weighted: Weight of 75% given to 8mm circle in center of frame; 3) Spot: Meters 3.5mm circle (about 2.5% of frame) centered on active focus area
Custom functions: 17
ISO range: 100 to 1,600 in steps of 1 EV with additional setting one step over 1600
White balance: Auto (TTL white-balance with 420-pixel RGB sensor), six manual modes with fine-tuning and preset white balance
Flash: 1) TTL: TTL flash control by 420-segment RGB sensor. i-TTL balanced fill-flash for digital SLR and standard i-TTL fill-flash for digital SLR available when CPU lens is used with built-in flash, SB-800, SB-600, and SB-400, 2) Auto aperture: Available with SB-800 with CPU lens, 3) Non-TTL Auto: Available with Speedlights such as SB-800, 80DX, 28DX, 28, 27, and 22s , 4) Range-priority manual available with SB-800
Sequence shooting: Approx. 2.5 frames per second (Approx. 1.7 frames per second with Noise reduction turned on and approx. 1 frame per second with ISO HI 1)
Storage Media: SD memory card, SDHC compliant
Viewfinder: Fixed-eyelevel penta-Dach mirror type; built-in diopter adjustment (-1.7 to +0.5m-1) (95% coverage)
LCD monitor: 2.5-inch 230,000-dot, low-temperature polysilicon TFT LCD with brightness adjustment
PC interface: USB 2.0 (High-speed): Mass Storage and PTP selectable
Power supply: EN-EL9 rechargeable lithium-ion battery (up to 520 shots/charge)
Dimensions (wxhxd): Approx. 126 x 64 x 94mm
Weight: Approx. 495g (without battery, memory card, lens or body cap)