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ISO Sensitivity / Noise levels

ISO equivalence on a digital camera is the ability to increase the sensitivity of the sensor. This works by turning up the "volume" (gain) on the sensor's signal amplifiers (remember the sensor is an analogue device). By amplifying the signal you also amplify the noise which becomes more visible at higher ISOs. Many modern cameras also employ noise reduction and / or sharpness reduction at higher sensitivities.


To measure noise levels we take a sequence of images of a GretagMacBeth ColorChecker chart (controlled artificial daylight lighting). The exposure is matched to the ISO (ie. ISO 200, 1/200 sec for consistency of exposure between cameras). The image sequence is run through our own proprietary noise measurement tool (version 1.5 in this review). Click here for more information. (Note that noise values indicated on the graphs here can not be compared to those in other reviews.)

Canon PowerShot G10 vs Panasonic Lumix DMC-LX3 vs Nikon COOLPIX P6000 vs Canon PowerShot G9

Canon PowerShot G10
ISO 80
Panasonic Lumix DMC-LX3
ISO 80
Nikon Coolpix P6000
ISO 64
Canon PowerShot G9
ISO 80
Canon PowerShot G10
ISO 100
Panasonic Lumix DMC-LX3
ISO 100
Nikon Coolpix P6000
ISO 100
Canon PowerShot G9
ISO 100
Canon PowerShot G10
ISO 200
Panasonic Lumix DMC-LX3
ISO 200
Nikon Coolpix P6000
ISO 200
Canon PowerShot G9
ISO 200
Canon PowerShot G10
ISO 400
Panasonic Lumix DMC-LX3
ISO 400
Nikon Coolpix P6000
ISO 400
Canon PowerShot G9
ISO 400
Canon PowerShot G10
ISO 800
Panasonic Lumix DMC-LX3
ISO 800
Nikon Coolpix P6000
ISO 800
Canon PowerShot G9
ISO 800
Canon PowerShot G10
ISO 1600
Panasonic Lumix DMC-LX3
ISO 1600
Nikon Coolpix P6000
ISO 1600
Canon PowerShot G9
ISO 1600

The G10 increased the resolution on what was already a tightly packed small sensor from the G9. The resolution is almost up to the 15MP of the EOS 50D, which is the highest resolution on even APS-C sensors (much larger than the sensor in the G10). With small sensors such as this, there is a delicate balance between retaining detail, especially at high ISOs, and keeping the noise levels down, usually using in-camera noise reduction. Even though the G10 uses the new Digic IV processing engine, which offers control over the amount of noise reduction in other cameras, the G10 has no such option (this is the same as the G9).

The noise performance looks to be slightly better than the G9 (though only slightly), despite the increase in resolution. The detail retained at higher ISOs is better on the G10 compared to the G9, while the noise is a finer grain and less obtrusive. From ISO 200 onwards, the G10 is noticeably producing better fine detail while keeping the noise levels lower than the G9 - quite an achievement given the increase in sensor resolution.

You can see in this test the two different approaches taken by Canon and Panasonic. The LX3 retains more detail from ISO 400 and above, and while it would seem that there is more noise in the gray patches with the LX3, the balance between fine detail and noise is better in the LX3. You can also see that of the three current cameras the Nikon P6000 is the worst performer in terms of noise and fine detail at all ISO settings, and especially over ISO 800. The highest full resolution setting for the G10 is ISO 1600, while the LX3 and P6000 can go to ISO 3200 (the P6000 can go even higher at reduced resolution, but looking at the ISO 1600 output, you might wonder why).

It should be noted that with almost 15mp on the G10, the noise and noise reduction up to ISO 400 will not be noticeable in prints at smaller sizes.

Low contrast detail

What the crops and graph don't show is the effect of noise reduction on low contrast fine detail such as hair, fur or foliage. An inevitable side effect of noise removal is that this kind of detail is also blurred or smeared, resulting in a loss of 'texture'. In a new test the crops below show the effect of the noise reduction on such texture (fur) as you move up the ISO range.

100% Crops
ISO 80 ISO 100 ISO 200
ISO 400 ISO 800 ISO 1600

The G9 balanced detail and noise quite well at ISO 200 and below, and the G10 continues this trend despite the increase in resolution. The amount of detail resolved at ISO 100 and 80 are almost identical. Once ISO 400 is reached, the resolved detail is much reduced. Even at ISO 80 there is definitely noise reduction and sharpening going on. ISO 800 and ISO 1600 continue to be emergency settings. When looking at these crops, you need remember that these are 100% crops and that in print or on screen at lesser magnifications the loss of detail will be much less noticeable. Canon wisely limits the highest ISO, when the camera is set to Auto ISO, to ISO 200.

Luminance noise graph

Cameras compared:
Canon PowerShot G10, Panasonic Lumix LX3, Nikon COOLPIX P6000

Indicated ISO sensitivity is on the horizontal axis of this graph, standard deviation of luminosity is on the vertical axis.

All 3 cameras produce quite low noise at settings of ISO 400 and below. While the G10 manages to produce low noise levels at higher ISO settings, the amount of detail retained is less than the LX3 (see compare pages later in this review). The measured differences in the noise produced by the three cameras is mostly down to in camera noise reduction.

RGB noise graph

Indicated ISO sensitivity is on the horizontal axis of this graph, standard deviation of each of the red, green and blue channels is on the vertical axis.

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