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ISO Sensitivity / Noise levels

ISO equivalence on a digital camera is the ability to increase the sensitivity of the sensor. The 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 ISO's. 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 (i.e. ISO 200, 1/200 sec for consistency of exposure between cameras). The image sequence is run through our own proprietary noise measurement tool (version 1.4 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). Room temperature is approximately 22°C (~72°F), simulated daylight lighting.

Olympus E-30 vs. Sony DSLR-A700 vs. Canon EOS 50D vs. Nikon D300

  • Olympus E-30: Olympus 50 mm F2.0 Macro lens, Manual exposure, Manual WB,
    Default Parameters (Natural), JPEG Large / Super Fine

  • Canon EOS 50D: Canon 50 mm F1.4 lens, Manual exposure, Manual WB,
    Default Parameters (Standard), High ISO NR (Default; Off), JPEG Large / Fine

  • Nikon D300: Nikkor 50 mm F1.4 lens, Manual exposure, Manual WB,
    Default Parameters (Normal), High ISO NR (Normal), JPEG Large / Fine

  • Sony DSLR-A700: Minolta 50 mm F1.4 lens, Manual exposure, Manual WB,
    Default Parameters (Standard), High ISO NR (Normal - default), JPEG Large / Fine  
Olympus E-30
ISO 100
Canon EOS 50D
ISO 100
Nikon D300
ISO 100
Sony DSLR-A700
ISO 100
Olympus E-30
ISO 200
Canon EOS 50D
ISO 200
Nikon D300
ISO 200
Sony DSLR-A700
ISO 200
Olympus E-30
ISO 400
Canon EOS 50D
ISO 400
Nikon D300
ISO 400
Sony DSLR-A700
ISO 400
Olympus E-30
ISO 800
Canon EOS 50D
ISO 800
Nikon D300
ISO 800
Sony DSLR-A700
ISO 800
Olympus E-30
ISO 1600
Canon EOS 50D
ISO 1600
Nikon D300
ISO 1600
Sony DSLR-A700
ISO 1600
Olympus E-30
ISO 3200
Canon EOS 50D
ISO 3200
Nikon D300
ISO 3200
Sony DSLR-A700
ISO 3200

Although there's not much difference at lower ISO settings, once you get past ISO 800 the varying image noise characteristics become quite obvious. At higher ISOs the E-30's output is slightly but visibly noisier than the other cameras in this comparison. Chroma noise (in the form of diffuse color blobs) is visible but is more or less under control. The luminance noise (grain) on the other hand is, despite being heavily battled by the camera's noise reduction, still visibly more pronounced than on the competitors. A significant amount of fine detail is blurred away by the noise reduction algorithms.

* It's worth noting that these results are with the cameras in their default modes, all of them offer 4 noise reduction options. You'll find the E-30's on the next page; to see the others please check out the relevant pages in each review:

High ISO noise comparison, Noise reduction OFF

Below we've put ISO 1600 and 3200 side by side from each of the four models above using the lowest available in-camera noise reduction setting, for those who like to shoot JPEG but would rather see a more 'honest' output for post-processing:

Olympus E-30
ISO 1600
Noise Filter OFF
Canon EOS 50D
ISO 1600
NR OFF
Nikon D300
ISO 1600
NR OFF
Sony DSLR-A700
ISO 1600
NR OFF
Olympus E-30
ISO 3200
Noise Filter OFF
Canon EOS 50D
ISO 3200
NR OFF
Nikon D300
ISO 3200
NR OFF
Sony DSLR-A700
ISO 3200
NR OFF

Even with their noise-filters switched off most cameras still apply a degree of noise reduction to their JPEG-output. Within this comparison the E-30 appears to be the only camera on which 'Off' actually does mean something approaching really off (certainly for luminance noise - chroma noise is still being blurred away). If you decide to shoot at this setting you get much better detail but you'll also have to live with a lot of noise but at least you can use a noise-reduction method of your choice rather than having to rely on the in-camera algorithms.

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