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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 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 (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). Room temperature is approximately 22°C (~72°F), simulated daylight lighting.

Panasonic DMC-G1 vs. Olympus E-520 vs. Canon EOS 450D vs Sony DSLR-A350

  • Panasonic DMC-G1: Olympus 50 mm F2.0 Macro lens with DMW-MA1APP adapter,
    Manual exposure, Manual WB, Default Parameters (Standard), NR (0 - default), JPEG Large / Fine
     
  • Olympus E-520: Olympus 50 mm F2.0 Macro lens, Aperture Priority, Manual WB,
    Default Parameters (Normal), High ISO NR (Normal), JPEG Large/Fine
     
  • Canon EOS 450D: Canon 50 mm F1.4 lens, Aperture Priority, Manual WB,
    Default Parameters (Standard PS), High ISO NR (Default; Off), JPEG Large/Fine

  • Sony DSLR-A350: Minolta 50 mm F1.4 lens, Aperture Priority, Manual WB,
    Default Parameters (Normal), JPEG Large/Fine
Panasonic G1
ISO 100
Olympus E-520
ISO 100
Canon EOS 450D
ISO 100
Sony DSLR-A350
ISO 100
Panasonic G1
ISO 200
Olympus E-520
ISO 200
Canon EOS 450D
ISO 200
Sony DSLR-A350
ISO 200
Panasonic G1
ISO 400
Olympus E-520
ISO 400
Canon EOS 450D
ISO 400
Sony DSLR-A350
ISO 400
Panasonic G1
ISO 800
Olympus E-520
ISO 800
Canon EOS 450D
ISO 800
Sony DSLR-A350
ISO 800
Panasonic G1
ISO 1600
Olympus E-520
ISO 1600
Canon EOS 450D
ISO 1600
Sony DSLR-A350
ISO 1600
Panasonic G1
ISO 3200
n/a
n/a Sony DSLR-A350
ISO 3200

   

As expected, at at base ISO there is not a big difference between the cameras' output. The G1 image is pretty clean with good detail. It can't quite keep up with the 450D but is visibly sharper than the E-520. We are suspecting Panasonic is, as usual, using a weaker AA-filter than Olympus although both manufacturers deploy Four Thirds sensors in their DSLRs.

As we move up the sensitivity scale noise levels are of course increasing but at standard settings Panasonic has managed to come up with a pretty well balanced approach to noise reduction. The G1 applies only comparatively small amounts of luminance noise reduction but is quite heavy on the chroma noise. As a result the images retain relatively good detail up fairly high sensitivities although from ISO1600 the deterioration in detail becomes clearly visible. Luminance noise is starting to become more intrusive at these sensitivities as well but it has a grainy, almost film-like appearance that is much more acceptable than the chroma noise color blotches that we can see for instance on the A350.

The ISO 3200 setting is no doubt quite noisy (from ISO 1600 onwards we also see chroma noise creeping in quite heavily) but it retains more detail and shows less chroma noise than the Sony and is certainly still good enough for emergency use. All in all Panasonic's noise reduction routines probably have to deal with more 'base level' sensor noise (check the RAW noise comparison below) than some of its APS-C competitors but they are doing a good job reducing noise in a way that leads to visually pleasing results.

Gray luminance noise graph

The graphs below confirm our observations on the sample images. The G1's firmware keeps noise under control up to ISO 800 before both measured chroma and luminance noise go through the roof at higher sensitivities. There is visibly and measurably more noise in the G1 output than in some of the competitors in this comparison but nevertheless the G1's noise reduction is clever enough to make the end result look quite favorable.

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

Black luminance noise graph

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

Chroma (color) noise graph

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

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Comments

marc petzold

I still like to have my G1 as a walk-around tool, for just the photograph by accident. the kitlens still performs well, even with the distortions, but therefore PTlens comes in way handy, all in all, even 2014 a good walk-by setup for the unexpected shot.

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