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ISO (Sensitivity) Adjustment

ISO equivalence on a digital camera is the ability to increase the sensitivity of the CCD to allow for faster shutter speeds and/or better performance in low light. The way this works in a digital camera is by "turning up the volume" on the CCD's signal amplifiers, nothing is without its price however and doing so also amplifies any noise that may be present and often affects colour saturation.

The DiMAGE 5 has four selectable ISO sensitivities of 100, 200, 400 and 800 as well as Auto mode which varies sensitivity between ISO 100 and 200 automatically depending on available light. Test images shot under both good and low light.

Good Light (11 EV) Low Light (3 EV)
ISO 100, 1/30 s, F4.8 ISO 100, 1.4 s, F4.8
ISO 200, 1/60 s, F4.8 ISO 200, 1 s, F4.8
ISO 400, 1/125 s, F4.8 ISO 400, 1/3 s, F4.8
ISO 800, 1/362 s, F4.8 ISO 800, 1/8 s, F4.8

Fairly clean, usable ISO 100 and 200 (although noise is visible on dark areas), noise creeps in at ISO 400 but images are still usable. ISO 800 is very noisy and should only be used if you intend to size reduce (downsample) the images later.


White Balance

Just like the DiMAGE 7 and S304 the DiMAGE 5's automatic white balance appears to be tuned to natural light, which is logical as this is where the majority of shots will be taken. The pre-programmed settings worked fairly well, especially for incandescent light. The manual preset option produced consistent and accurate white balance.

Images re-saved to sRGB colour space [info]

Outdoors, Auto Outdoors, Cloudy (or Daylight) Outdoors, Manual
Incandescent, Auto Incandescent, Incandescent Incandescent, Manual
Fluorescent, Auto Fluorescent, Fluorescent Fluorescent, Manual

First word indicates the light in which the shot was taken, the second indicates the selected white balance mode.


Macro Focus

Macro focus is only available with the zoom set between 200 and 250 mm (as 35mm equiv. focal lengths) as indicated by a small arrow and line on the zoom grip. It is engaged by sliding a small switch forwards on the lens barrel, the camera can now focus between 25 cm - 60 cm (9.8 - 23.6 in). This means that when shooting macros 25 cm (9.8 in) is as close as you can get, however thanks to the magnification at 250 mm (equiv.) you can still shoot very respectable macros. We measured the closest frame coverage to be approximately 4.2 cm (1.7 in) across the entire frame.

Images re-saved to sRGB colour space [info]


Low Light Focus

In a new addition to our reviews we'll now be measuring 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 2.0 EV (10.0 Lux / 0.9 foot-candle)
Telephoto (250 mm) F3.5 3.2 EV (23.0 Lux / 2.1 foot-candle)

Light intensity (Lux) = 2.5 x 2^EV (@ ISO 100), 10.76391 Lux = 1 foot-candle (fc)

As you can see the DiMAGE 5 needs quite a bit of light to focus, at wide angle (35 mm, F2.8) it needs as much light as it's little brother the S304 needed at full telephoto (F3.5). At full telephoto (250 mm, F3.5) things get even harder, the DiMAGE 5 needed 3.2 EV of light to get a focus lock on our 'ideal target'. Remember these values are the best you could expect given a high contrast subject.

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