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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 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

Leica Digilux 2 vs. Canon PowerShot G5

Note that there was a third stop difference in sensitivity between the Digilux 2 and the Canon PowerShot G5, this essentially means that the Digilux 2 set to ISO 100 is approximately the same sensitivity as ISO 80 (although you can't select this ISO) would be on the G5.

  Leica Digilux 2
n/a
Canon PowerShot G5
ISO 50
, 1/50 sec, F4.5
 Partial crop
Red Green Blue
channels
  Leica Digilux 2
ISO
100, 1/100 sec, F4.0
Canon PowerShot G5
ISO 100
, 1/100 sec, F4.5
 Partial crop
Red Green Blue
channels
  Leica Digilux 2
ISO
200, 1/200 sec, F4.0
Canon PowerShot G5
ISO 200
, 1/200 sec, F4.5
 Partial crop
Red Green Blue
channels
  Leica Digilux 2
ISO
400, 1/400 sec, F4.0
Canon PowerShot G5
ISO 400, 1/400 sec, F4.5
 Partial crop
Red Green Blue
channels

A look at the crops above and the noise graph below clearly demonstrates that the Digilux 2 is cleaner (has less noise) than the PowerShot G5 at the same sensitivities. The graph below gives away how the camera achieves this, by using noise reduction. I suspect that there is some moderate noise reduction being carried out at ISO 100 but at ISO 200 and 400 this becomes much stronger with fairly obvious 'watercolor type' effects on flat areas of the image. It's a pity Leica didn't choose to implement an ISO 50 setting on the camera because this would have produced very nice 'silky smooth' images.

Luminance noise graph

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.


Noise reduction effectiveness

Below are set of 480 x 200 crops (at 100%) from a sequence of exposures taken by each camera (Leica Digilux 2 and Canon PowerShot G5) at each ISO sensitivity. Shots were taken in a dimly lit room. As we get higher up the ISO range you can see that the Digilux 2's noise reduction does a good job of keeping 'flat area noise' to a minimum by effectively blurring the noise away, this at the expense of some detail and the artificial pasty watercolor effect visible in some parts of the image.

Canon PowerShot G5, ISO 50, F5.6, 0.8 sec (1,803 KB)
Leica Digilux 2, ISO 100, F5.0, 0.4 sec (3,213 KB)
Canon PowerShot G5, ISO 100, F5.6, 0.4 sec (2,144 KB)
Leica Digilux 2, ISO 200, F5.0, 1/5 sec (3,255 KB)
Canon PowerShot G5, ISO 200, F5.6, 1/5 sec (2,552 KB)
Leica Digilux 2, ISO 400, F5.6, 1/10 sec (3,822 KB)
Canon PowerShot G5, ISO 400, F5.6, 1/10 sec (2,976 KB)

More crops from Digilux 2 vs. PowerShot G5 @ ISO 400

Below you will find some more 100% crops from the Leica Digilux 2 and Canon PowerShot G5 at ISO 400. This further demonstrates that the Digilux 2's noise reduction is effective however there is a price to pay with some parts of the image looking processed and slightly artificial. In my opinion Leica should have provided the photographer with the ability to control noise reduction (eg. off, low, high, auto).

Leica Digilux 2, ISO 400 Canon PowerShot G5, ISO 400
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yomasa
By yomasa (3 months ago)

junk

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