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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.

Unlike the EOS 30D the EOS 40D proved to have the same sensitivity as indicated, much in line with what we've seen from other recent Canon digital SLRs and has been the case for most other brand SLRs.

Indicated
sensitivity
Canon EOS 40D
(actual sensitivity)
Nikon D200
(actual sensitivity)
Pentax K10D
(actual sensitivity)
ISO 100 ISO 100 ISO 100 ISO 100
ISO 200 ISO 200 ISO 200 ISO 200
ISO 400 ISO 400 ISO 400 ISO 400
ISO 800 ISO 800 ISO 800 ISO 800
ISO 1600 ISO 1600 ISO 1600 ISO 1600
ISO 3200 ISO 3200 ISO 3200 n/a

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.

Canon EOS 40D vs. Nikon D200 vs. Pentax K10D

  • Canon EOS 40D: Canon 50 mm F1.4 lens, Aperture Priority, Manual WB,
    Default Parameters (Standard PS), High ISO NR (Default; Off), JPEG Large / Fine
     
  • Nikon D200: Nikkor 50 mm F1.4 Macro lens, Aperture Priority, Manual WB,
    Default Parameters (Normal), High ISO NR (Normal), JPEG Large / Fine
     
  • Pentax K10D: Pentax 50 mm F1.4 lens, Aperture Priority, Manual WB,
    Default Parameters (Natural), JPEG Large / Fine
Canon EOS 40D
ISO 100
Nikon D200
ISO 100
Pentax K10D
ISO 100
Canon EOS 40D
ISO 200
Nikon D200
ISO 200
Pentax K10D
ISO 200
Canon EOS 40D
ISO 400
Nikon D200
ISO 400
Pentax K10D
ISO 400
Canon EOS 40D
ISO 800
Nikon D200
ISO 800
Pentax K10D
ISO 800
Canon EOS 40D
ISO 1600
Nikon D200
ISO 1600
Pentax K10D
ISO 1600
Canon EOS 40D
ISO 3200
Nikon D200
ISO 3200
Pentax K10D
n/a

From ISO 100 to 400 there's very little to choose between these three cameras, at ISO 800 we begin to see some chroma noise in the K10D's gray crop as well as the effects of luminance noise reduction in the detail of the D200 crop. At ISO 1600 the difference grows, the EOS 40D and K10D maintaining more detail than the D200 but both with more visible chroma noise (thanks to Nikon's stronger chroma noise reduction). At ISO 3200 the 40D is looking much better than the D200 with considerably better detail reproduction and lower (although color mottled; this can be reduced, see next page) noise levels overall.

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

Total comments: 2
reanim888

Very very sad because though the 40D isn't missing any feature in particular--though I could make a case for mechanical image stabilization--one feature I'd really like to see trickle down from the 1D series, and which I think makes a lot of sense in a camera of this class, is the ability to define acceptable ranges for aperture, shutter speed, and ISO sensitivity when shooting in one of the exposure-priority modes.

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figoral

the new version looks better in the statistics but for my needs the EOS 30D is sufficient. Regards
http://www.teletechnika-system.pl/

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Total comments: 2