Nikon D3S ISO Quality Tests
By Olin Lathrop, 24 March 2011
I recently acquired a Nikon D3S camera, so am trying to get a good feel
for its capabilities and tradeoffs. One feature of this camera that
is supposed to be particularly outstanding is its low light capability,
which means good quality at high ISO equivalent settings.
This type of image sensor can trade off sensitivity with noise.
Better sensors will allow higher sensitivity at the same noise, or less
noise at the same sensitivity. These tests are intended to get a
feeling of the noise versus sensitivity choices of the D3S, to provide
guidance on what ISO settings produce acceptable results in different
The camera was set on a tripod with a 50mm fixed lens set to f/8.
The ISO sensitivity was varied by one f-stop (factor of 2) in successive
pictures, with the camera automatically adjusting the shutter speed to
compensate. The shutter speed varied from 1/30 second for the ISO
200 picture and was faster for successive pictures. All pictures
were taken within a minute of each other on 9 January 2011 outdoors during
the day under heavy overcast conditions. These conditions did not
change noticably over the set of test pictures. The full frames
are 4256 x 2832 pixels in resolution, which is the maximum the D3S can
produce. The highest quality mode was used.
Two images are shown for each test picture. The left image shows
a 160 x 120 piece of the original picture, pixel replicated 2 x 2 to make
the pixels easier to see on the screen. In other words, the image
on the screen is 320 x 240 pixels, but shows a blowup of a 160 x 120
region of the original picture. To put in perspective how small a
portion of the original picture that shows, consider that the original
picture would about 25½ times wider at that scale. The
purpose of this image is to show the raw pixel noise.
The right image of each pair was made by first resizing the original
picture to 1024 x 681 pixels, then extracting a 320 x 240 region from
it. The full image at that scale would be 3.2 times wider.
The purpose of this image is to show the effects of the pixel noise at
roughly the largest reasonable size for a picture in a web page. Put
another way, spacial resolution can be traded off to get lower noise, and
this image gives some idea of the result for about a 4x shrink in each
dimension. This will give some guidance of what ISO settings are
acceptable if the full frame picture is intended ultimately for display in
a web page or similar resolution.
|Full frame at 640 x 426 pixels for scale reference
The results are for everyone to interpret for themselves.
However, my own conclusions are:
- The Nikon D3S does indeed have a impressive image sensor!
- There is little reason to use less than ISO 1600 for ordinary
shooting, even if you think the original picture will be needed at its
full resolution. Even ISO 3200 is going to be good enough for
most purposes most of the time. I'll keep my camera set to ISO
1600, and then move up from there as light conditions dictate, without
agonizing too much over pixel noise. I'll only go down for special
effects, like when I deliberately want a slow shutter speed to show
- For most outdoor daylight pictures, you can set it to ISO 1600
and forget about it.
- If you know the full frame will be displayed at a small size,
such as in a web page, there is no penalty for using high ISO
settings. Yes, there is more pixel noise, but this will be lost
when the image is shrunk (and thereby filtered) to its final size.
- While there is certainly pixel noise at higher ISO settings, it
is relatively small from the context of the whole picture. If a
higher ISO setting otherwise makes a picture better, like allowing a
faster shutter speed and therefore less shaking artifacts with a long
lens, go ahead and use the higher ISO setting. For example, the
shaking artifacts of handholding the camera with a 300mm lens at ISO
1600 and 1/30 second are likely going to be worse than the pixel noise
at ISO 12800 and thereby allowing 1/240 second exposure and the
resulting 1/8 the shaking artifacts.
Nice job, Nikon.