ISO Sensitivity / Noise levels

Standard Test

ISO equivalence on a digital camera is the ability to increase the sensitivity of the sensor to enable 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 noise and can also affect colour saturation.

The EXILIM EX-Z3 provides three selectable sensitivities of ISO 50, 100 and 200. Our noise comparison test involves shooting a color patch chart (a GretagMacBeth ColorChecker) at the full range of ISO sensitivities and then measuring luminance and RGB noise at a 'mid' grey patch.

Casio EXILIM EX-Z3 vs. Pentax Optio S

Measurements taken at approximately 21°C (~70°F). Lighting was daylight. Manual white balance.

	ISO 50
	Casio EXILIM EX-Z3 1/40 sec, F4.8	Pentax Optio S 1/40 sec, F4.8
Original crop
Red channel
Green channel
Blue channel
	ISO 100
	Casio EXILIM EX-Z3 1/80 sec, F4.8	Pentax Optio S 1/80 sec, F4.8
Original crop
Red channel
Green channel
Blue channel
	ISO 200
	Casio EXILIM EX-Z3 1/160 sec, F4.8	Pentax Optio S 1/200 sec, F4.8
Original crop
Red channel
Green channel
Blue channel

As we may expect the EXILIM EX-Z3 exhibits virtually identical noise to the Optio S at each of the selectable sensitivities.

Luminance noise graph

Note that indicated ISO sensitivity is on the horizontal axis of this graph.

RGB noise graph

Note that indicated ISO sensitivity is on the vertical axis of this graph.