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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. This gives a measure of standard output specification (SOS) sensitivity according to the ISO12232:2006 standard. We estimate the accuracy of these results to be +/- 1/6 EV.

Indicated
ISO value
Ricoh GXR/S10
measured*
Canon G11
measured*
Panasonic LX3
measured*
Panasonic GF1
measured*
ISO 100
125
80
80
125
ISO 200
250
160
160
250
ISO 400
500
320
320
500
ISO 800
1000
640
640
1000
ISO 1600
2500
1250
1250
2000
ISO 3200
5000
2500
2500
4000

* Approximate values, default settings.

The GXR with the 24-72mm lens module, like the Panasonic GF1, is approximately a third of a stop more sensitive than the indicated ISO. However, the gap between indicated and actual ISO increases at the two highest settings. The Canon G11 and Panasonic LX 3 are roughly one third of a stop less sensitive (therefore giving darker images).

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

Ricoh GXR/S10 vs Canon G11 vs Panasonic LX3 vs Panasonic GF1

  • Ricoh GXR/S10: Manual Exposure, Manual WB,
    Default Parameters, High ISO NR default (Off), JPEG Large / Fine
     
  • Canon Powershot G11: Aperture Priority, Manual WB, Default Parameters (Standard),
    JPEG Large / Fine
     
  • Panasonic DMC-LX3: Aperture Priority, Manual WB, Default Parameters, JPEG Large / Fine

  • Panasonic DMC-GF1: Olympus 50 mm F2.0 Macro lens (via adapter), Manual Exposure,
    Manual WB, Default Parameters, Noise Reduction Standard (0), JPEG Large / Fine
  Ricoh GXR/S10 Canon G11 Panasonic LX3 Panasonic GF1
ISO 80    
ISO 100
ISO 200
ISO 400
ISO 800
ISO 1600
ISO 3200

In the comparison between these four cameras the different noise characteristics and approaches towards noise reduction become apparent from pretty early on. On the Ricoh and Canon the effects of fairly strong noise reduction and loss of fine detail are visible from ISO 400. The Canon image is the cleanest but this is achieved through very high levels of noise reduction, resulting in very soft images without hardly any low contrast detail at higher sensitivities. The Panasonic LX3 takes a different approach. There is significantly more grainy luminance noise visible in its output but also slightly more detail than in the Canon images.

The Ricoh S10 in a way combines the worst elements of these two different approaches. Strong noise reduction is applied but does not entirely get rid of the image noise. The result is a very soft, at high sensitivities almost detail-free, image that also has quite a lot of unattractively blurred but clearly visible noise in it. Chroma noise is on a similar level as the Canon though.

It's not a surprise that the Panasonic GF1 with its larger Micro Four Thirds sensor produces the best results in this comparison. At the highest sensitivities is shows some visible luminance noise and very little chroma (color) noise but crucially maintains very good detail up to the highest settings.

Noise graphs

The graphs below show what we have seen in the sample crops above. The Panasonic LX3 measures the highest and the Canon G11 the lowest noise levels in all categories. What the chart does not show is that the Panasonic retains more fine detail in its images. In numerical terms the Panasonic GF1 does an average job but as we've seen above it produces by far the best end results. The Ricoh S10 is on one level with the Canon G11 in terms of chroma and gray luminance noise but measures higher black luminance noise. However, in the crops we've seen that these relatively low figures are being paid for by a significant loss of fine detail.

  Ricoh GRX/S10
Chroma
Black
Gray
Indicated ISO sensitivity is on the horizontal axis of this graph, standard deviation of luminosity on the vertical axis.

RAW noise

Finally let's take a look a the S10 24-72mm's RAW output next to the competition. Removing any in-camera noise reduction and processing the images using Adobe Camera Raw (V5.6 in this case, all NR set to 0) gives us the nearest thing to a 'level playing field' for assessing the relative noise levels of the four cameras' sensors.

With noise reduction turned off we get a more accurate idea of how noisy these sensors are and the image looks slightly different to what we've seen above in the JPEG section of this page. The Canon G11 is almost on the same noise levels as the Panasonic LX3. The Ricoh output is quite similar to the Canon's up to ISO400 but at higher sensitivities Ricoh clearly applies some noise reduction to the S10's RAW files. The GF1, despite of being quite noisy at the very highest settings, produces by far the most detailed output at all sensitivities over ISO400.

  Ricoh GXR/S10 RAW Canon G11 RAW Panasonic LX3 RAW Panasonic GF1 RAW
ISO 80    
ISO 100
ISO 200
ISO 400
ISO 800
ISO 1600
ISO 3200

Raw Noise graphs

Here the graphs confirm what we can see in the sample crops. The break in the S10 curve at ISO400 shows that Ricoh is applying noise reduction to its RAW files at higher sensitivities. The Panasonic measures the lowest noise levels.

  Ricoh GXR/S10
Chroma
Black
Gray
Indicated ISO sensitivity is on the horizontal axis of this graph, standard deviation of luminosity on the vertical axis.
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