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 length of exposure between cameras). Note that this wasn't exactly possible on the S3 Pro because of its 0.5 EV exposure steps (we got as close as we could).

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)

Fujifilm S3 Pro vs. Canon EOS 20D (ISO 100 - 3200)

• Fujifilm S3 Pro: Nikkor 50 mm F1.4 lens, Aperture Priority, Manual WB,
  Default Parameters, JPEG Fine, Standard Dynamic Range
  
• Canon EOS 20D: Canon 50 mm F1.4 lens, Aperture Priority, Manual WB,
  Parameters 1 (default), JPEG Large / Fine

Fujifilm S3 Pro @ 6 mp ISO 100, 1/90 sec, F3.3	Fujifilm S3 Pro @ 12 mp ISO 100, 1/90 sec, F3.3	Canon EOS 20D ISO 100, 1/100 sec, F4
Fujifilm S3 Pro @ 6 mp ISO 200, 1/180 sec, F3.3	Fujifilm S3 Pro @ 12 mp ISO 200, 1/180 sec, F3.3	Canon EOS 20D ISO 200, 1/200 sec, F4
Fujifilm S3 Pro @ 6 mp ISO 400, 1/350 sec, F3.3	Fujifilm S3 Pro @ 12 mp ISO 400, 1/350 sec, F3.3	Canon EOS 20D ISO 400, 1/400 sec, F4
Fujifilm S3 Pro @ 6 mp ISO 800, 1/750 sec, F3.3	Fujifilm S3 Pro @ 12 mp ISO 800, 1/750 sec, F3.3	Canon EOS 20D ISO 800, 1/800 sec, F4
Fujifilm S3 Pro @ 6 mp ISO 1600, 1/1500 sec, F3.3	Fujifilm S3 Pro @ 12 mp ISO 1600, 1/1500 sec, F3.3	Canon EOS 20D ISO 1600, 1/1600 sec, F4
Fujifilm S3 Pro @ 6 mp n/a	Fujifilm S3 Pro @ 12 mp n/a	Canon EOS 20D ISO 3200, 1/3200 sec, F4

One of the S3 Pro's biggest competitors (assuming you're not locked into the Nikon lens mount) is the Canon EOS 20D. If you scan down the gray patch comparison you can see that from ISO 100 to 400 noise levels are as good as identical and at ISO 800 and 1600 the S3 Pro appears cleaner. Look at the detail crop however and the reason becomes evident, the S3 Pro's aggressive high ISO noise reduction takes its toll on image detail, while areas of continuous tone are smooth, detail is lost elsewhere in the image. It's a tradeoff that Fujifilm should perhaps have left in the hands of the photographer (user controllable noise reduction).

Fujifilm S3 Pro vs. Nikon D70 (ISO 100 - 1600)

• Fujifilm S3 Pro: Nikkor 50 mm F1.4 lens, Aperture Priority, Manual WB,
  Default Parameters, JPEG Fine, Standard Dynamic Range
  
• Nikon D70: Nikkor 50 mm F1.4 lens, Aperture Priority, Manual WB,
  Default Parameters, JPEG Large / Fine

Fujifilm S3 Pro @ 6 mp ISO 100, 1/90 sec, F3.3	Fujifilm S3 Pro @ 12 mp ISO 100, 1/90 sec, F3.3	Nikon D70 n/a
Fujifilm S3 Pro @ 6 mp ISO 200, 1/180 sec, F3.3	Fujifilm S3 Pro @ 12 mp ISO 200, 1/180 sec, F3.3	Nikon D70 ISO 200, 1/200 sec, F3.5
Fujifilm S3 Pro @ 6 mp ISO 400, 1/350 sec, F3.3	Fujifilm S3 Pro @ 12 mp ISO 400, 1/350 sec, F3.3	Nikon D70 ISO 400, 1/400 sec, F3.5
Fujifilm S3 Pro @ 6 mp ISO 800, 1/750 sec, F3.3	Fujifilm S3 Pro @ 12 mp ISO 800, 1/750 sec, F3.3	Nikon D70 ISO 800, 1/800 sec, F3.5
Fujifilm S3 Pro @ 6 mp ISO 1600, 1/1500 sec, F3.3	Fujifilm S3 Pro @ 12 mp ISO 1600, 1/1500 sec, F3.3	Nikon D70 ISO 1600, 1/1600 sec, F3.5

Much cheaper but no less competitive the Nikon D70 delivers an impressive performance in maintaining detail all the way through its sensitivity range however its noise levels are noticeably higher from ISO 800 to 1600. This was a choice made by Nikon, rather than use strong noise reduction which would affect image detail they decided to maintain it. The other thing that's noteworthy is that the D70's noise is more luminance based (like film grain) rather than colored blotches.

Changing the dynamic range setting on the S3 Pro had only a subtle effect on noise as can be seen in the graph below, most noticeable was a slight increase in luminance noise at ISO 200. We can surmise that the smaller R-Pixels have a lower signal to noise ratio (higher noise) and hence must also have noise reduction applied at higher sensitivities, in this case we're probably near the crossover between little noise reduction and 'some'.

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.