Low Light Focus
This test measures the minimum amount of light under which the camera can still focus. The focus target is our lens distortion test chart (shown here on the right), camera is positioned exactly 2 m (6.6 ft) away.
Light levels are gradually dropped until the camera can no longer focus. This is carried out at both wide angle and telephoto zoom positions (as more light reaches the focusing systems with a larger aperture).
This test target is the optimum type of subject for most "contrast detect" AF systems (as it has a vertical line at its center), you should consider the results below the best you could expect to achieve.
|Lens position||Aperture||Lowest light focus|
|Wide angle (35 mm)||F2.8||2.1 EV (10.7 Lux, 1.0 foot-candle)|
|Telephoto (70 mm)||F4.0||2.5 EV (14.1 Lux, 1.3 foot-candle)|
Light intensity (Lux) = 2.5 x 2^EV (@ ISO 100), 10.76391 Lux = 1 foot-candle (fc)
The DX4900 doesn't have an AF assist lamp, however it does still manage to perform at about the average of what we'd expect at this price point. These light levels are what you would have in a medium lit room.
The DX4900's internal flash unit has a quoted range of 0.5 - 3.2 m (1.6 - 10.5 ft) at wide angle and 0.5 - 2.3 m (1.6 - 7.5 ft) at telephoto. In use the flash performed quite well, we saw no evidence of blue colour cast which can sometimes be a problem with consumer digital cameras. We were also fairly impressed with the camera's ability meter flash power correctly.
Barrel and Pincushion Distortion
The DX4900's small 2x optical zoom lens performed very well in our distortion tests. It exhibited a very small 0.7% barrel distortion (almost nothing) at wide angle and no measurable pincushion distortion at telephoto. This is a good performance, however remember that this lens does have a limited zoom range.
|Barrel Distortion, 0.7% @ wide angle||Pincushion Distortion, 0% @ telephoto|
Purple Fringing (Chromatic Aberrations)
The DX4900 did unfortunately suffer from a combination of purple fringing and blooming around bright or overexposed image areas (such as chrome). The sample below demonstrates this fairly clearly and the DX4900 also performed worse than most recent digital cameras on our chromatic aberration test shot.
|Hard pressed to find evidence of chromatic aberrations in "every day" shots|
|Our now standard chromatic aberration test shot - mostly blooming|
Overall Image Quality / Specific Issues
Overall the DX4900 delivers relatively detailed but occasionally 'over processed' or soft looking images. Not at the top of the four megapixel scale in terms of resolution and quality but somewhere around average. As we've come to expect from Kodak colour is good, as is (generally speaking) metering. However, the DX4900 did have a few niggling problems (in addition to the purple fringing noted above).
As noted previously in this review the in-camera sharpness adjustment appears to control the amount of noise reduction applied to the image. This implies that there is a 'residual' noise level even at ISO 100. This noise can occasionally be seen around detail areas of images where they are adjacent to 'flat area'. The flat areas tend to be smoothed by the cameras noise reduction system which stops just prior to a change in colour or the introduction of detail. This tends to reveal the underlying noise. This can be seen around the edges of detail in the crops below.