ISO / Sensitivity accuracy

The actual sensitivity of each indicated ISO is measured using the same shots as are used to measure ISO noise levels, we simply compare the exposure for each shot to the metered light level (using a calibrated Sekonic L-358), middle gray matched. We estimate the accuracy of these results to be +/- 1/6 EV. These tests are based on the sRGB JPEG output of the cameras, in accordance with ISO 12232:2006, the standard used by camera manufacturers.

Indicated
ISO value
Olympus E-PL1
measured value*
Panasonic GF1
measured value*
Nikon D3000
measured value*
ISO 100
ISO 100
ISO 125
ISO 100
ISO 200
ISO 200
ISO 250
ISO 200
ISO 400
ISO 400
ISO 500
ISO 400
ISO 800
ISO 800
ISO 1000
ISO 800
ISO 1600
ISO 1600
ISO 2000
ISO 1600
ISO 3200
ISO 3200
ISO 4000
ISO 3200

JPEG 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 (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 1.6 in this review). Click here for more information. Room temperature is approximately 22°C (~72°F), simulated daylight lighting.

Olympus E-PL1 vs. Panasonic GF1 vs. Olympus E-P1 vs. Nikon D3000

  • Olympus E-PL1: Olympus 50 mm F2 Macro lens (@F6.3), Manual Exposure,
    JPEG Large/SHQ, Manual WB, Default Parameters (Standard), Self-Timer with Anti-Shock
     
  • Panasonic DMC-GF1: Olympus 50 mm F2 Macro lens (@F6.3), Aperture Priority,
    JPEG Large/Fine, Manual WB, Default Parameters (Standard), Self-Timer
     
  • Olympus E-P1: Olympus 50 mm F2 Macro lens (@F6.3), Aperture Priority,
    JPEG Large/SHQ, Manual WB, Default Parameters (Standard), Self-Timer

  • Nikon D3000: Nikkor 50 mm F1.4 G lens, Manual Exposure, Manual WB,
    Default Parameters (Normal), High ISO NR (Normal), JPEG Large / Fine
  Olympus E-PL1 Panasonic GF1 Olympus E-P1 Nikon D3000
ISO 100
ISO 200
ISO 400
ISO 800
ISO 1600
ISO 3200

The most surprising thing about this test is how much better than the E-P1 the E-PL1's images seem to be. The amount of detail retained at high ISO is immediately apparent, with sharper, more detailed images all the way from ISO 400 upwards. The E-PL1 is not only doing a better job here than either of the other Micro Four Thirds cameras, but is also doing a better job of balancing noise and detail than the larger-sensored D3000.

RAW noise

The RAW data takes away the effect of each camera's JPEG engine and any backstage wizardry each manufacturer might be conducting.

  Olympus E-PL1 Panasonic GF1 Olympus E-P1 Nikon D3000
ISO 100
ISO 200
ISO 400
ISO 800
ISO 1600
ISO 3200

Noise reduction and fine detail

The biggest issue with noise reduction - especially luminance noise reduction - is that in the process of blurring away the noise it can also have a very destructive effect on the detail in an image, particularly the fine, low contrast detail you might find in hair, fur or grass. To better judge the effect on fine detail lost due to noise reduction we have shot our new studio scene and produced crops from the feathers in the image. We have left out the 'Low' noise reduction setting as it only appears to apply chroma noise reduction which tends to have little impact on detail (fine contrast).

To check the effect of noise and noise reduction on low contrast detail we shoot our new studio setup at various ISO and noise reduction settings, then crop an area that's challenging to any camera. The very fine detail in the feathers will help to better judge the effect of noise reduction on fine detail.

Raw vs in-camera JPEG noise reduction low contrast detail comparison

Turning noise filter 'off' doesn't appear to quite turn noise reduction off altogether (there's so little chroma noise, you have to assume it's being removed), but leaves lots of detail. This removal of chroma (color) noise means that the relatively subtle 'Low' noise filter option, that leaves a little bit of luminance noise strikes what we think is the best balance between noise suppression and detail retention. The default 'Normal' setting is also pretty good at this balance until very high ISOs, whereas we think the 'High' setting is a bit too aggressive.

Ultimately, the JPEG engine is doing a great job of controlling noise while retaining detail and gives a sensible level of control, to provide output that will satisfy most people.

  ACR RAW NR OFF JPEG NR-Off JPEG NR-Normal JPEG NR-High
ISO 200
ISO 200
ISO 400
ISO 800
ISO 1600
ISO 3200