One of the criteria that every camera review site uses in evaluating the quality of a new camera is image noise. As ISO increases noise normally increases as the sensor capture capabilities (or lack thereof) and boost processing electronics take their toll on the quality of the captured image.

There are many things that affect that noise, not the least of which is the size of the light-gathering pixels that capture the image. As discussed in detail in The Digital Sensor and The Digital Sensor Part 2, the size of the photosite is the reason the tiny sensors used in pocket point and shoot cameras are so limited in capabilities compared to the Digital SLR, which is where the major growth in the photographic market is now occurring.


The impact of photosite size is ably demonstrated in one of today's hottest DSLR cameras - the Nikon D3. This $5000 camera is a 12.2MP full-frame camera. Since it can also handle Nikon DX crop lenses and create a 5MP image at the common APS-C size seen in most of today's DSLR cameras, it is easy to understand that this 12MP full-frame has the same photosite size as a 5MP crop-sensor DSLR.

As discussed in detail in the Digital Sensor articles, the sensor is an analog light-gathering device. It is not a simple digital on-or-off digital device where size really matters very little. In a camera sensor the light gathering is analog and the larger the light gathering area, all else being equal, the better the light gathering ability.

Compared to today's 10 to 14.6MP sensors in top DSLR cameras with a 14x24 sensor, the Nikon D3 has huge photosites in its 24x36mm 12MP sensor. Combined with CMOS technology and evolved electronics the Nikon D3 has a normal ISO range to ISO 6400. As a comparison, the Canon XSI top sensitivity is 1600 and most prosumer models extend to ISO 3200.


As you can see in this dramatic ISO 6400 hockey shot produced by Dave Black for Nikon, D3 images at ISO 6400 are extremely low noise. Even more impressive is the ability to still capture usable images at ISO 12800 and all the way to ISO 25600 with much increased noise in a pinch.

Clearly noise is related to the size of pixels in analog sensors, but that is only part of the story. Often the manufacturer of the camera has made decisions, either informed or due to lack of expertise, to not process for noise at high ISO. Cameras that appear to exhibit much increased noise at high ISOs are sometimes capable of much lower noise. The poor noise performance is sometimes the result of decisions by the camera maker in how files will be converted to RAW or JPEG files in camera or in post-processing software.

The Sigma SD14 Wakeup Call
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  • GoSharks - Thursday, July 31, 2008 - link

    I agree that the box is a horrible test subject. dpreview's (for one example) shots of a grey patch, and then multiple crops of a high detail image are excellent for showing the level of noise AND detail that exist at each ISO setting. The box only gives you the level of noise, which is only half the story. Reply
  • marokero - Monday, July 28, 2008 - link

    Was the photog shooting through the windows inside a grounded helicopter?

    I've been shooting with a D3 since February, and I've been getting images that were just "not doable" below ISO 6400 without a flash - and a flash would've ruined the moment. Yes, David Black could've used a slower shutter speed and lower ISO to get the same exposure, but would he have been able to freeze the hockey action at 1/125s and ISO 800? I seriously doubt it.

    I surely would like more manufacturers to implement some of Foveon's X3 layered tecnology in their future sensors, but not at the cost of reduced light sensitivity. Noiseware, Noise Ninja, Neat Image... they all do a fine job of cleaning up noise, but they do not do miracles.
    Reply
  • peroni - Monday, July 28, 2008 - link

    Sorry Wesley but this article should be withdrawned, the quality is not on par with the rest of this site articles.

    p.s.
    In nearly all the pictures you have posted the originals look better.


    Reply
  • Deadtrees - Monday, July 28, 2008 - link

    The selling point of Sigma cameras are their sharp/full-of-detail images yet the reviwer thinks it's better to smear all of those in favor of low noise. That's just stupid.

    If he buys a Ferrari, he'd cripple the engine for the sake of low noise, then talk about how great it is to have low noise on Ferrari.

    Reply
  • pepsimax2k - Monday, July 28, 2008 - link

    is that dido on the main page pic?

    woohoo *wins award for least geeky anandtech post in, ohh, 5 minutes?*
    Reply
  • Deadtrees - Monday, July 28, 2008 - link

    1. That D3 ISO 6400 sample image has shutter speed of 1/1000. Even Nikon D70 or Canon A350 that are known for high noise would only show minimal noise when it's shot in the bright area.
    Don't get me wrong, I'm not saying D3 low-noise/high-ISO sucks. D3, without a doubt, shows the least noise out of all the cameras in market. However, showing ISO 6400 image with shutter speed of 1/1000 and saying 'look at this low noise in ISO 6400' is simply wrong. Hell, I can even show you low-noise ISO 1600 images with D70 so you can talk about how D70 shows very little noise.


    2. "However, many incorrectly criticize Sony, for instance, on their "heavy" image processing in the A350. Canon and Nikon also heavily process images in-camera; they just make slightly different choices in their processing algorithms."

    That's because, as you know, Sony kills noise in favor of detail and they do it way too much. What good is 14.2MP when it's crippled; in other word, you don't get to see the advantage of 14.2MP when the ISO goes up as the noise processing algorithm kills most of the details. Again, Canon and Nikon doesn't smear images as Sony does.

    3. Either your expectation is too low or my expectation is too high, but Imageware creates really smeared images just like Sonys'. Well, if you are a fan of watercolor-like or plastic-like pictures that shows the least detail, I guess Imageware is all good. But....really....pictures processed with Imageware really look terrible.
    Given that, I hope you don't waste your money getting quality lenses. You'd be fine with lenses made with window glasses.
    Reply
  • Wesley Fink - Monday, July 28, 2008 - link

    I suppose we will all have to chide Nikon for their obvious stupidity. The Hockey image was supplied by Nikon as an example ISO 6400 image in their D3 launch kit. Reply
  • Deadtrees - Monday, July 28, 2008 - link

    No, the problem is you saying 'Look at this image! it's ISO 6400 and shows so little noise!' Reply
  • Some1ne - Monday, July 28, 2008 - link

    It completely ruins all the detail in all the photos that include bodies of water. Seriously, in the Noiseware processed one you can't see any of the ripples/waves/other details in the water anymore. Terrible! Reply
  • Ratinator - Monday, July 28, 2008 - link

    Has anyone heard anything about when Kodak is going to release their new filter that was discussed about a year ago mentioned here http://www.dpreview.com/news/0706/07061401kodakhig...">http://www.dpreview.com/news/0706/07061401kodakhig...

    Reply

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