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ISO Sensitivity / Noise levels


Standard Test
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 measurement tool which measures the standard deviation (normalized) of the middle gray patch (indicated by the red rectangle above). Additionally we now have a 'detail crop', this is currently a postage stamp (lots of fine detail) but we may replace this at a future date. Note that noise values indicated on the graphs below should not be compared to those in other reviews.

Test notes:

  • Shots taken at approximately 22°C (~72°F)
  • Lighting was simulated daylight measured as 10.1 EV (at ISO 100)

Olympus E-300 EVOLT vs. Canon EOS 20D (ISO 100 - 3200)

  • Olympus E-300: Olympus 50 mm F2.0 lens, Aperture Priority, Manual WB,
    Default Parameters, JPEG SHQ
  • Canon EOS 20D: Canon 50 mm F1.4 lens, Aperture Priority, Manual WB,
    Parameters 1 (default), JPEG Large / Fine
  Olympus E-300
ISO 100
, 1/100 sec, F3.5
Canon EOS 20D
ISO 100
, 1/100 sec, F4
Crops
  Olympus E-300
ISO 200
, 1/200 sec, F3.5
Canon EOS 20D
ISO 200
, 1/200 sec, F4
Crops
  Olympus E-300
ISO 400, 1/400 sec, F3.5
Canon EOS 20D
ISO 400
, 1/400 sec, F4
Crops
  Olympus E-300
ISO 800
, 1/800 sec, F3.5
Canon EOS 20D
ISO 800
, 1/800 sec, F4
Crops
  Olympus E-300
ISO 1600
, 1/1600 sec, F3.5
Canon EOS 20D
ISO 1600
, 1/1600 sec, F4
Crops
  Olympus E-300
n/a
Canon EOS 20D
ISO 3200
, 1/3200 sec, F4
Crops

Although not a direct competitor to the Canon EOS 20D the E-300 does become the third only eight megapixel digital SLR and so comparisons will be made (and can be interesting). At ISO 100 the two are virtually indistinguishable, from ISO 200 to 400 the 20D looks cleaner although it's a moderate difference. At ISO 800 the 20D begins to look much cleaner, and at ISO 1600 there's almost no comparison, a large jump in noise is apparent in the E-300 sample. Visually the EOS 20D at ISO 3200 doesn't look that much noisier than the E-300 at ISO 800.

The Canon EOS 300D / Digital Rebel has almost identical noise characteristics as the EOS 20D. For those who need to know the E-300 uses a Kodak CCD, the EOS 20D a Canon CMOS sensor.

Olympus E-300 EVOLT vs. Nikon D70 (ISO 100 - 1600)

  • Olympus E-300: Olympus 50 mm F2.0 lens, Aperture Priority, Manual WB,
    Default Parameters, JPEG SHQ
  • Nikon D70: Nikkor 50 mm F1.4 lens, Aperture Priority, Manual WB,
    Default Parameters, JPEG Large / Fine
  Olympus E-300
ISO 100
, 1/100 sec, F3.5
Nikon D70
n/a
Crops
  Olympus E-300
ISO 200
, 1/200 sec, F3.5
Nikon D70
ISO 200
, 1/200 sec, F3.5
Crops
  Olympus E-300
ISO 400, 1/400 sec, F3.5
Nikon D70
ISO 400
, 1/400 sec, F3.5
Crops
  Olympus E-300
ISO 800
, 1/800 sec, F3.5
Nikon D70
ISO 800
, 1/800 sec, F3.5
Crops
  Olympus E-300
ISO 1600
, 1/1600 sec, F3.5
Nikon D70
ISO 1600
, 1/1600 sec, F3.5
Crops

A glance at the luminance noise graph below and you may think that the E-300's noise levels were fairly similar to the D70 (at least up to ISO 800), and from a luminance point of view they are. However we also see color, and if you look at the RGB noise graph you will see that the E-300 exhibits more noise in its red and blue channels than green (which is primarily responsible for luminance), where as the D70's noise is virtually equal across all channels.

Luminance noise graph

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

RGB noise graph

Indicated ISO sensitivity is on the horizontal axis of this graph, standard deviation of each of the red, green and blue channels (normalized image) are on the vertical axis.

RGB channels compared, ISO 400

As you can see from the break-out of the individual RGB channels in the ISO 400 samples below (and the graph above) the E-300 has the majority of its noise in the red and blue channels, this leads to a more color speckled appearance to noise, the best being the D70 which does well to keep noise fairly equal across all channels.

  Red Green Blue
Olympus
E-300
Canon
EOS 20D
Nikon
D70
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Comments

reanim888

Amazing!
The Olympus E-300 functions far more like a DSLR in terms of shot to shot recording rate, but still a bit slow when contrasted with Canon and Nikon’s sub-$1,000 offerings. The E-300 will capture subsequent images with just .59 seconds between. This remains slightly behind the XT’s .33 seconds and the D70’s .35 seconds recording rate, but still far beyond most compact models.

1 upvote