Previous page Next page

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.

Sony DSLR-A900 vs. Canon EOS 5D vs. Nikon D700 vs. Canon EOS-1Ds Mark III

  • Sony DSLR-A900: Sony 85 mm F1.4 lens, Manual exposure, Manual WB,
    Default Parameters (Standard), High ISO NR (Normal - default), JPEG Large / Fine
     
  • Nikon D700: Nikkor 85 mm F1.8 lens, Manual exposure, Manual WB,
    Default Parameters (Normal), High ISO NR (Default: Normal), JPEG Large / Fine
     
  • Canon EOS 5D: Canon 85 mm F1.8 lens, Aperture Priority, Manual WB,
    Default Parameters (Standard), JPEG Large / Fine
     
  • Canon EOS 1-DS Mark III: Canon 85 mm F1.8 lens, Manual exposure, Manual WB,
    Default Parameters (Standard), High ISO NR (Default; Off), JPEG Large / Fine

Sony DSLR-A900
n/a

Nikon D700
n/a
Canon EOS 5D
ISO 50
Canon EOS 1DS Mark III
ISO 50

Sony DSLR-A900
ISO 100

Nikon D700
ISO 100
(L1.0)
Canon EOS 5D
ISO 100
Canon EOS 1DS Mark III
ISO 100

Sony DSLR-A900
ISO 200
Nikon D700
ISO 200
Canon EOS 5D
ISO 200
Canon EOS 1DS Mark III
ISO 200

Sony DSLR-A900
ISO 400
Nikon D700
ISO 400
Canon EOS 5D
ISO 400
Canon EOS 1DS Mark III
ISO 400
Sony DSLR-A900
ISO 800
Nikon D700
ISO 800
Canon EOS 5D
ISO 800
Canon EOS 1DS Mark III
ISO 800

Sony DSLR-A900
ISO 1600
Nikon D700
ISO 1600
Canon EOS 5D
ISO 1600
Canon EOS 1DS Mark III
ISO 1600

Sony DSLR-A900
ISO 3200
Nikon D700
ISO 3200
Canon EOS 5D
ISO 3200
Canon EOS 1DS Mark III
ISO 3200

Sony DSLR-A900
ISO 6400
Nikon D700
ISO 6400
Canon EOS 5D
n/a
Canon EOS 1DS Mark III
ISO 6400

Using the default settings on all four cameras (we'll look at raw output on the next page) produces some interesting though hardly surprising results. Up to ISO 400 there's not a lot in it (certainly not when you take into account the resolution difference) - though the A900 does show a touch more noise than its competitors. Measured noise as you move up the ISO range is broadly the same for all cameras, though one glance at the crops above should be enough to tell you that Sony is making increasingly desperate attempts to control noise through pretty brutal noise reduction as you head up the scale. By ISO 3200 the result is a blurry mess with little fine detail - with the added insult of visible chroma noise in the shadow areas. I think it's fair to say that ISO 3200 and 6400 are firmly in the 'emergency use only' bracket (of course with 24MP to play with you shouldn't have many problems at small print sizes).

Noise graphs

Note that we normally show both gray and black results on the same graph, comparing four cameras this became too difficult to read hence we have two separate graphs, one for the gray patch (middle gray) and one for the black patch (shadows).

Luminance noise graph (gray patch)

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

Luminance noise graph (black patch)

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

Chroma (color) noise graph

The Alpha 900 shows slightly higher chroma noise than the other cameras in the group until you hit ISO 1600 when the noise reduction really kicks in.

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

Previous page Next page
119
I own it
21
I want it
41
I had it
Discuss in the forums

Comments