ISO Sensitivity / Noise levels

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" on the CCD's signal amplifiers, nothing is without its price however and doing so also amplifies any noise that may be present and often affects colour saturation.

The D100 provides a good range of selectable sensitivities between ISO 200 and 1600 in 1/3 stop steps. In addition it also provides HI-1 and HI-2 sensitivities which are the equivalent of ISO 3200 and 6400.

Our noise comparison test involves shooting a colour patch chart (a GretagMacBeth ColorChecker) at the full range of ISO sensitivities and then measuring noise at three patch positions.

Each of the comparison crops below are made up of a 180 x 80 crop of patches 19, 22 and 24 of the ColorChcker chart (as indicated above). This helps to give a better impression of noise at different light levels within an image. Directly below this you will find the average standard deviation of these three patches, this is a quantifiable measurement of noise.

UPDATE 30th July 2002: Due to concerns aired by some posters on the Nikon SLR Talk forum I have re-run this test and re-compiled the results. The outcome was as I expected, results were within 2% of our original test measurements. Also note that the noise graphs now include results from the Fujifilm S2 Pro and that ISO 100, 3200 and 6400 results are also included.

Test Notes

• We are now using the GretagMacBeth ColorChecker instead of Kodak Colour patches for a couple of reasons: (a) The grey patches are larger and are therefore easier to crop / measure (b) The patches are made from a matte non-reflective material and are therefore easier to shoot without accidental reflection.
• Both cameras were configured as close to normal 'every day' use as possible, this means Normal sharpening on the D100 and the same on the EOS-D60. Using Auto sharpening on the D100 would have introduced more noise (as Auto tends to sharpen more).
• Measurements were taken at approximately 23°C (~73°F), you should expect more noise at higher temperatures and less at lower temperatures.
• Nikon RAW images converted to 8-bit TIFF using Nikon Capture 3.0, default settings (camera settings carried through).
• Canon RAW images converted to 8-bit TIFF using Canon RAW Image Converter v2.0.2, default settings (camera settings carried through).
• Nikon D100: Normal Sharpening, Auto Tone, Colour Mode I (sRGB), Manual WB
• Canon EOS-D60: Default Parameters (Normal Sharpening, Contrast, Saturation and Tone), Manual WB
• Lighting: Daylight
• The 'standard deviation' was measured using the histogram feature in Photoshop on 8-bit TIFF or JPEG files (later comparison). Lower figures mean there is less 'deviation' from the average luminance level, and thus less noise.

Nikon D100 (JPEG) vs. Canon EOS-D60 (JPEG)

Camera	Nikon D100	Canon EOS-D60
Sensitivity	n/a	ISO 100
Exposure	n/a	1/15 sec, F8.0
Patch crops  ISO 100  JPEG
Standard dev. avg.	-	0.65
Camera	Nikon D100	Canon EOS-D60
Sensitivity	ISO 200	ISO 200
Exposure	1/30 sec, F8.0	1/30 sec, F8.0
Patch crops  ISO 200  JPEG
Standard dev. avg.	1.25	0.86
Camera	Nikon D100	Canon EOS-D60
Sensitivity	ISO 400	ISO 400
Exposure	1/60 sec, F8.0	1/60 sec, F8.0
Patch crops  ISO 400  JPEG
Standard dev. avg.	1.56	1.39
Camera	Nikon D100	Canon EOS-D60
Sensitivity	ISO 800	ISO 800
Exposure	1/125 sec, F8.0	1/125 sec, F8.0
Patch crops  ISO 800  JPEG
Standard dev. avg.	2.03	2.50
Camera	Nikon D100	Canon EOS-D60
Sensitivity	ISO 1000	ISO 1000
Exposure	1/160 sec, F8.0	1/160 sec, F8.0
Patch crops  ISO 1000  JPEG
Standard dev. avg.	2.29	3.14
Camera	Nikon D100	Canon EOS-D60
Sensitivity	ISO 1600	n/a
Exposure	1/250 sec, F8.0	n/a
Patch crops  ISO 1600  JPEG
Standard dev. avg.	2.91	-
Camera	Nikon D100	Canon EOS-D60
Sensitivity	ISO 3200	n/a
Exposure	1/500 sec, F8.0	n/a
Patch crops  ISO 3200  JPEG
Standard dev. avg.	4.34	-
Camera	Nikon D100	Canon EOS-D60
Sensitivity	ISO 6400	n/a
Exposure	1/1000 sec, F8.0	n/a
Patch crops  ISO 6400  JPEG
Standard dev. avg.	6.58	-

Overall noise levels are very low (compared to what we've seen in the past). With JPEG images it's interesting to see noise levels on the D100 start higher than the EOS-D60 but remain at a lower level at higher sensitivities. Below ISO 800 the D100 has consistently higher noise levels than the 'super smooth' EOS-D60, at and above ISO 800 the D100 holds its noise levels down well.

(ISO 3200 and 6400 results not included as they would affect the graph scale too much)

Nikon D100 (RAW) vs. Canon EOS-D60 (RAW)

Camera	Nikon D100	Canon EOS-D60
Sensitivity	n/a	ISO 100
Exposure	n/a	1/15 sec, F8.0
Patch crops  ISO 100  RAW
Standard dev. avg.	-	0.64
Camera	Nikon D100	Canon EOS-D60
Sensitivity	ISO 200	ISO 200
Exposure	1/30 sec, F8.0	1/30 sec, F8.0
Patch crops  ISO 200  RAW
Standard dev. avg.	1.53	0.83
Camera	Nikon D100	Canon EOS-D60
Sensitivity	ISO 400	ISO 400
Exposure	1/60 sec, F8.0	1/60 sec, F8.0
Patch crops  ISO 400  RAW
Standard dev. avg.	2.13	1.24
Camera	Nikon D100	Canon EOS-D60
Sensitivity	ISO 800	ISO 800
Exposure	1/125 sec, F8.0	1/125 sec, F8.0
Patch crops  ISO 800  RAW
Standard dev. avg.	2.82	2.07
Camera	Nikon D100	Canon EOS-D60
Sensitivity	ISO 1000	ISO 1000
Exposure	1/160 sec, F8.0	1/160 sec, F8.0
Patch crops  ISO 1000  RAW
Standard dev. avg.	3.31	2.56
Camera	Nikon D100	Canon EOS-D60
Sensitivity	ISO 1600	n/a
Exposure	1/250 sec, F8.0	n/a
Patch crops  ISO 1600  RAW
Standard dev. avg.	4.77	-
Camera	Nikon D100	Canon EOS-D60
Sensitivity	ISO 3200	n/a
Exposure	1/500 sec, F8.0	n/a
Patch crops  ISO 3200  RAW
Standard dev. avg.	7.13	-
Camera	Nikon D100	Canon EOS-D60
Sensitivity	ISO 6400	n/a
Exposure	1/1000 sec, F8.0	n/a
Patch crops  ISO 6400  RAW
Standard dev. avg.	10.49	-

Interestingly shooting RAW and converting to TIFF (without default settings in NC3) produced more noise than the EOS-D60 and more noise than JPEG images straight out of the camera. This hints that Nikon Capture is applying more sharpening to the image by default, even though it is supposed to match the camera processing.

(ISO 3200 and 6400 results not included as they would affect the graph scale too much)