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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 7 has four selectable ISO sensitivities of 100, 200, 400 and 800 as well 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 (10.7 EV) Low Light (2.7 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

Both ISO 100 and ISO 200 are fairly clean. It's fair to say that ISO 100 is no more noisy than some of todays 3 megapixel digital cameras. At ISO 400 and 800 noise gets progressively worse, it's visible as fairly 'sharp' primary coloured speckles, random, not patterned.


Picture Effects

The DiMAGE7 allows you to control three variables of its internal image processing algorithms, they are colour saturation, contrast and sharpening. This gives the photographer a good range of flexibility in controlling the way the final image will look, or even simply setting up the camera for his preferred balance. Below you'll find samples of the same scene shot with different values for each of these settings.


Picture Effects: Saturation

Images re-saved to sRGB colour space [info]

 
Saturation -3 Saturation -2  
Saturation -1 Saturation 0 Saturation +1
 
  Saturation +2 Saturation +3

It's nice to see a manufacturer providing fine gradations of control over internal algorithms, it means you can set the camera up in a way you prefer without spoiling the image. Some, will no doubt shoot at either +1 or +2 (which remind me of Sony colours).


Picture Effects: Contrast

Images re-saved to sRGB colour space [info]

 
Contrast -3 Contrast -2  
Contrast -1 Contrast 0 Contrast +1
 
  Contrast +2 Contrast +3

I personally used Contrast -1 for day-to-day shooting, it was the best setting to maintain both shadow detail and highlights.


Picture Effects: Sharpness

Sharpness: Hard (+)
Sharpness: Normal
Sharpness: Soft (-)

Here, my preference was for the Soft setting, as long as you actually post-process your images this is the best choice, it doesn't introduce sharpening artifacts (such as white halo around black details) or enhance noise.

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