ISO / Sensitivity accuracy

In a new addition to our reviews we are now measuring the actual sensitivity of each indicated ISO sensitivity. This is achieved 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 Sekonic L-358), middle gray matched. We estimate the accuracy of these results to be +/- 1/6 EV.

We found the M8 to be around a third of a stop (0.3 EV) more sensitive than indicated, this means that the base 'ISO 160' is actually more like ISO 200 all the way through to the maximum being closer to ISO 3200.

Indicated
sensitivity 		Leica M8
(actual sensitivity)		   Indicated
sensitivity 		Canon EOS 5D
(actual sensitivity)		 Nikon D200
(actual sensitivity)
      ISO 100 ISO 125 ISO 100
ISO 160 ISO 200   ISO 200 ISO 250 ISO 200
ISO 320 ISO 400   ISO 400 ISO 500 ISO 400
ISO 640 ISO 800   ISO 800 ISO 1000 ISO 800
ISO 1250 ISO 1600   ISO 1600 ISO 2000 ISO 1600
ISO 2500 ISO 3200   ISO 3200 n/a ISO 3200

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 (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 1.4 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.

Leica M8 vs. Canon EOS 5D vs. Nikon D200

  • Leica M8: Leica Summicron-M 50 mm F2.0 lens, Manual exposure, Manual WB,
    Default Parameters, JPEG Large / Fine
     
  • Canon EOS 5D: Canon 50 mm F1.4 lens, Aperture Priority, Manual WB,
    Default Parameters (Standard PS), JPEG Large / Fine
     
  • Nikon D200: Nikkor 50 mm F1.8 lens, Aperture Priority, Manual WB,
    Default Parameters (Normal), JPEG Large / Fine
Leica M8
n/a		 Canon EOS 5D
ISO 100 (125 equiv.) 		Nikon D200
ISO 100
Leica M8
ISO 160 (200 equiv.) 		Canon EOS 5D
ISO 200 (250 equiv.) 		Nikon D200
ISO 200
Leica M8
ISO 320 (400 equiv.) 		Canon EOS 5D
ISO 400 (500 equiv.) 		Nikon D200
ISO 400
Leica M8
ISO 640 (800 equiv.) 		Canon EOS 5D
ISO 800 (1000 equiv.) 		Nikon D200
ISO 800
Leica M8
ISO 1250 (1600 equiv.) 		Canon EOS 5D
ISO 1600 (2000 equiv.) 		Nikon D200
ISO 1600
Leica M8
ISO 2500 (3200 equiv.)		 Canon EOS 5D
ISO 3200 (4000 equiv.) 		Nikon D200
ISO 3200

From ISO 160 (200 equiv.) to 1250 (1600 equiv.) the flat area noise profile (gray and black patches) of the M8 is fairly similar to that of the EOS 5D and D200, however the M8 does maintain detail better than the D200 at ISO 1600, this apparently due to less (or better) noise reduction. At ISO 3200 the EOS 5D delivers the most detail with the M8 image affected mostly by chroma (color blotching) noise. The graphs below support this, what's interesting is that the M8's profile is very similar to that of the D200 but as mentioned it doesn't suffer the same degradation of detail at ISO 1600 and 3200 (equiv.).

Luminance noise graph

Actual ISO sensitivity on the horizontal axis, standard deviation of luminosity on the vertical axis.

Chroma (color) noise graph

Actual ISO sensitivity on the horizontal axis, standard deviation of color on the vertical axis.

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