Previous page Next page


ISO Sensitivity / Noise levels


Standard Test

ISO equivalence on a digital camera is the ability to increase the sensitivity of the sensor to enable faster shutter speeds and/or better performance in low light. The way this works in a digital camera is by "turning up the volume" (gain) on the CCD's signal amplifiers. Nothing is without its price however and doing so also typically increases visible noise (random speckles visible all over the image).

We are now using a more reliable, repeatable and neutral method for evaluating noise. Shots are taken in daylight lighting in our studio. Noise is measured as the standard deviation of the medium gray patch on a Gretag MacBeth ColorChecker chart. The image is normalized before measurement of noise to remove the possibility of figures being affected by image contrast (one method of masking noise). Note that noise numbers shown on the graphs below can not be compared to those in older reviews.

Test notes:

  • Shots taken at approximately 21°C (~70°F)
  • Lighting was simulated daylight
  • Manual white balance
  • Aperture Priority

Canon PowerShot Pro1 vs. Olympus C-8080 WZ

  Canon PowerShot Pro1
ISO 50
, 1/50 sec, F4.5
Olympus C-8080 WZ
ISO 50
, 1/50 sec, F4.5
 Partial crop
Red Green Blue
channels
  Canon PowerShot Pro1
ISO
100, 1/100 sec, F4.5
Olympus C-8080 WZ
ISO 100
, 1/100 sec, F4.5
 Partial crop
Red Green Blue
channels
  Canon PowerShot Pro1
ISO
200, 1/200 sec, F4.5
Olympus C-8080 WZ
ISO 200
, 1/200 sec, F4.5
 Partial crop
Red Green Blue
channels
  Canon PowerShot Pro1
ISO
400, 1/400 sec, F4.5
Olympus C-8080 WZ
ISO 400, 1/400 sec, F4.5
 Partial crop
Red Green Blue
channels

This comparison shows quite clearly that at ISO 50 noise levels from both cameras are very low and it's very difficult to distinguish which is better. At ISO 100 visible 'speckle' noise from the Pro1 becomes more noticeable, from here upwards the C-8080 Wide Zoom manages to keep noise in check while it simply becomes more and more noticeable in the Pro1 images. It's clear that the C-8080 is using a noise reduction algorithm to keep noise in check, its noise increases but appears more 'blotchy' and smeared. Overall the C-8080 looks better.

Canon PowerShot Pro1 vs. Nikon Coolpix 8700

  Canon PowerShot Pro1
ISO 50
, 1/50 sec, F4.5
Nikon Coolpix 8700
ISO 50
, 1/50 sec, F3.9
 Partial crop
Red Green Blue
channels
  Canon PowerShot Pro1
ISO
100, 1/100 sec, F4.5
Nikon Coolpix 8700
ISO 100
, 1/100 sec, F3.9
 Partial crop
Red Green Blue
channels
  Canon PowerShot Pro1
ISO
200, 1/200 sec, F4.5
Nikon Coolpix 8700
ISO 200
, 1/200 sec, F3.9
 Partial crop
Red Green Blue
channels
  Canon PowerShot Pro1
ISO
400, 1/400 sec, F4.5
Nikon Coolpix 8700
ISO 400, 1/400 sec, F3.9
 Partial crop
Red Green Blue
channels

In this comparison things are much closer, both cameras exhibiting roughly the same levels of noise throughout their sensitivity range. Interestingly the Nikon tends towards a green shift at higher sensitivities, this only seemed to occur in our studio and we weren't able to replicate this in normal 'everyday' situations.

Luminance noise graph

As you can see from the five way comparison below the Canon, Nikon and Sony have very similar noise levels throughout the ISO sensitivity range. The Olympus C-8080 Wide Zoom and Konica Minolta DiMAGE A2 both manage to keep noise levels low, examining their images it's clear that they are both achieving this through noise reduction.

So is noise actually lower on the C-8080 and DiMAGE A2? Well, yes, but probably at the expense of a little detail. This shouldn't be a big issue at lower sensitivities (ISO 100 or 200).

Indicated ISO sensitivity is on the horizontal axis of this graph, standard deviation of luminosity (normalized) on the vertical axis. Note that we have standardized on a 0-10 scale.

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) are on the vertical axis. Note that we have standardized on a 0-10 scale.

Previous page Next page

Comments