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DxO Labs added scores for three Sony SLRs to its site for image sensor tests. (Click to enlarge.)

(Credit: DxO Labs)

Three midrange Sony SLRs now are included in DxO Labs' measurements of image sensor performance, and the Alpha A700 proves to be reasonably competitive.

Sony's A700, which costs about $1,100 with an 18-70mm lens, has a score of 66.3 on the test, which calculates how well the sensor handles color, a range brightness and darkness, and low-light shooting. That puts it behind the top-scoring camera with a comparably sized sensor, the Nikon D90, almost ties it with the Pentax K10D and Nikon D300, and gives it a a few points' lead over Canon's 40D and 50D.

Meanwhile, the A200 scores 62.9 and the A300 an even 64, according to the DxOMark Sensor test results that were updated Tuesday. A five-point difference makes a difference of about 1/3 stop in exposure, DxO says, meaning that a higher-scoring camera can attain the same raw image quality as a rival even though the higher-scoring camera is using a faster exposure or higher ISO.

DxO Labs, a French company, makes a business of measuring camera image quality, developing technology for image-processing hardware and software, and selling software to convert the raw files produced by higher-end cameras into less flexible but more convenient formats such as JPEG. The DxOMark score measures sensor performance based on the raw file, a foundation for overall image quality but only a facet of a camera's overall performance.

Close-up shot of Benchmark's DAC1 USB headphone amp is compatible with PC and Mac systems.

(Credit: Steve Guttenberg)

Sure, most AV receivers have "good enough" built-in headphone amplifiers, which are fine for occasional listening.

But if you regularly listen to a decent set of headphones over your home theater system or computer, I recommend moving up to a high-quality headphone amplifier, like Benchmark's DAC1 USB ($1,275).

AV receivers' headphone amps, even on $1,000+ models either sound anemic, with little or no bass, or they're muffled sounding things. Whenever I review high-end headphones, I always plug them into an iPod, AV receiver, and a dedicated headphone amplifier, just to see how they perform in different contexts. But headphones always do their best when plugged into a good headphone amp.

Grado GS-1000 headphones produces exciting sound.

(Credit: Steve Guttenberg)

Benchmark is one of the few manufacturers of professional audio gear that has consistently wowed audiophiles. The company offers a range of headphone amplifiers, and I reviewed the Benchmark DAC1 USB when I tested the Denon AH-D5000, Grado GS-1000, and Ultrasone Edition 9 luxury headphones for Home Entertainment magazine.

It looks like Canon and Nikon weren't blowing smoke when they said their high-end SLRs cameras will compete with medium-format digital cameras used almost exclusively by professionals.

Given the image quality advantages that SLRs with larger "full-frame" sensors have over mainstream and much less expensive models with smaller processors, one might have expected another quantum leap from costly high-end medium-format digital cameras with sensors twice the area of top-end SLRs. Not so, according to new DxOMark Sensor test results set for release Tuesday by French test and measurement firm DxO Labs.

In the digital era, Canon's top-end SLRs give medium-format cameras a run for their money. (Click to enlarge.)

(Credit: DxO Labs)

The company tested image sensors from several medium-format cameras--the Mamiya ZD Back, Leaf Aptus 75S, Hasselblad H3DII 39, and Phase One P45+. These are the sorts of cameras used by fashion photographers and others who need lush tones, fine detail, and lots of megapixels to handle big photos such as magazine spreads.

But none outperformed the Nikon D3X SLR, whose score of 88 gives it the current top rank on DxO's sensor tests.

With everything going green, it was only a matter of time before we added more power consumption testing in the labs. With all the advancements in graphic cards--multiple GPUs, multiple power connections, Crossfire, and SLI--they're now one of the biggest energy hogs in your rig. Our goal is to look at GPU power consumption and measure power vs. performance vs.cost.

The test bed is Intel-based, with a Core i7 965 processor at 3.20GHz and 4GB of DDR3 SDRAM at 1066MHz. The meter used to measure the system's power is a Watts up? Pro ES. Watts up? is a "plug load" meter that measures the amount of electricity used by whatever is plugged into it.

Testing is done in two states, first the idle test; this is where we simulate an end-user environment, by opening Internet Explorer, iTunes, and Windows Mail. We then let the system idle for about 5 minutes, export the results from the Watts up?, and use the average of the total idle watts for our score.

The next phase is a 3D high-end test, where we have Crysis running multiple runs at 1,600x1,200 resolution and, like the idle test, we export and average the data.

For a detailed look at the actual testing process, check out the gallery below for photos of our GPU power testing setup. To see the actual results of our power consumption testing, check out these recent graphics card reviews.

How much power does your video card use?

The top four SLRs in DxO Labs' current rankings.

(Credit: DxO Labs)

It's not a surprise that the Nikon D3X, the company's brand-new $8,000, 24.5-megapixel SLR, tops DxO Labs' sensor performance test. What is a surprise is the margin by which it leads its rivals from Canon and Sony.

When the French firm unveiled its DxOMark Sensor benchmark test last year, Nikon's D3 was the top scorer at 80.6, a composite number that represents various performance features. Very close on its heels were Nikon's D700 at 80.5, Canon's EOS-1Ds Mark III 80.3, and later Canon's 5D Mark II at 79 and Sony's Alpha A900 at 78.9.

All those cameras were close, but the D3X stands apart with a score of 88. The result shows how much ground Nikon has made up on Canon, which has dominated high-end digital SLR technology.

The Canon 5D Mark II is the new fourth-place member of DxO Labs' test of image sensor scores.

(Credit: DxO Labs)

One verdict is in on Canon's EOS 5D Mark II: its sensor ranks very high on DxO Labs' test of sensor performance.

The black-spot issue notwithstanding, Canon's new full-frame SLR came in at fourth place with a score of 79.0, bumping Sony's 78.9-scoring Alpha A900 down a peg but still trailing Canon's top-end EOS-1Ds Mark III at 80.3. Nikon's D700, the closest rival to the 5D Mark II, is a notch ahead at 80.5.

More relevant for the potential upgrade market, new Canon SLR's score is significantly better from that of its predecessor, the 5D, whose score is 70.9. On a pixel-by-pixel basis, the 12.8-megapixel 5D's sensor actually has a lower signal-to-noise ratio, but when measured over an entire 8x10 print, the 5D Mark II's higher 21.1-megapixel resolution wins on that measurement.

The DxOMark Sensor test measures how well a camera's sensor fares when it comes to dynamic range, color depth, and low-light performance. The test doesn't measure any number of other camera issues such as autofocus, value, or image processing. But it's still useful given DxO Labs' engineering rigor and the central role a sensor plays in the abilities of a camera.

Pixel-peepers have been devouring DxO's new statistics; the curious can try this link to a comparison of the 5D Mark II, Nikon D700, and Sony A900. However, it should be noted, DxO Labs considers that scores must be at least of 5 points apart to be significant.

There's been much discussion about whether the $2,700 5D Mark II performs better than the $6,500 1Ds Mark III, which has the same resolution. The DxOMark tests give the edge to the top-end model based on its better color and dynamic range--the ability to capture both bright and dark regions--but the 5D Mark II wins out in low-light performance. Digging deeper into the charts, though, the 5D Mark II fares better in dynamic range at higher ISOs.

The sensor on Canon's 5D Mark II fares significantly better than that on the 5D. (Click to enlarge.)

(Credit: DxO Labs)

All these cameras perform better than the common herd by virtue of full-frame sensors measuring 36x24mm, the size of a full frame of 35mm film. Most digital SLRs have a smaller sensor that can't capture as much information overall, but those models are vastly more affordable.

A correction was made to this story. See below for details.

DxO Labs, a French company with deep experience measuring cameras' technical performance, has launched a Web site called DxOMark.com that features detailed information on the performance of the image sensor at the heart of many higher-end digital cameras.

Many Web sites and magazines measure camera image quality with varying degrees of rigor, typically examining either the JPEG that the camera produces or a processed version of the camera's raw. But with its DxOMark Sensor measurement, DxO takes a new approach by judging the sensor performance based on the unprocessed "raw" image file from higher-end cameras such as SLRs.

That's significant, because raw images typically must go through a conversion process called demosaicing before they're useful for viewing. Most digital cameras capture only a single color--red, green, or blue--for each sensor pixel. Demosaicing fills in the gaps in this colored checkerboard pattern so each pixel gets all three color components, but this processing stage can disguise sensor performance.

The detail-obsessed camera crowd has begun eagerly chomping on the new data. On Sunday, there were 220 mentions of DxOmark on the Digital Photography Review forums, a popular location for impassioned technical discussions.

Nikon's D90 sensor beats out the one in Canon's 50D, judged on the basis of the raw files it produces.

(Credit: DxO Labs)

New tests coming
More measurements are coming, added Nicolas Touchard, vice president of marketing for DxO Labs' image quality evaluation business. First, in two or three weeks, will come measurements for medium-format digital camera sensors from companies including Hasselblad, Mamiya, Phase One, and Leaf. Then will come more high-end compact "bridge" cameras.

DxOMark Image Processing for the camera's computer, whose job it is to perform tasks such as converting raw images to JPEG, and DxOMark Optics for lenses.

The latter measurement will go beyond most lens tests by showing how well each lens works on each camera rather than one or two reference models. DxO takes that approach because lenses behave differently because different cameras have different attributes such as the geometry of the microlenses that help each sensor pixel gather more light, Touchard said.

DxO makes a business out of detailed measurements of camera performance, selling the data to camera and chip companies and incorporating it into its own DxO Optics Pro raw-processing software for photographers. So why give some of the data away for free on a Web site? Publicity.

... Read more

We test monitor contrast ratio in a secret, undisclosed location.

(Credit: Eric Franklin/CNET Networks)

Vendors want to sell you stuff! There, it's finally been said. Don't believe me? Well, you wouldn't be the first, but thankfully, I have evidence.

Within the last year I've seen a new spec, called dynamic contrast ratio (DCR), tossed around for computer displays. If you didn't know before, contrast ratio is simply the difference between the darkest blacks and the brightest whites a given display can produce.

Typically, computer displays have a contrast ratio of about 1000:1. However with DCR, you'll see numbers like 4000:1, 10,000:1, and higher. Basically, it's just a way for Company A to proclaim, "Don't buy Company B's monitor because it has a much lower DCR than our monitor." Since more and more vendors have been pushing this, I want to delve further into how they're getting these numbers. I also covered this topic in less detail (but with a sexy voice thrown in) in episode 2 of the Inside CNET Labs podcast.

Before a monitor is released to the public it goes through a bunch of testing in the vendor's own lab. These tests produce the specs that the vendor will then publish with the release. Specs like maximum brightness, pixel pitch, pixel response time, contrast ratio, and dynamic contrast ratio are all determined in the vendor's own lab.

When testing normal contrast ratio, vendors use a device that measures light to determine how much light is emanating from a display while it's showing both a completely black and a completely white screen. They then take each number, do a bit of math, and come up with the contrast ratio.

The Kramer VM-2DVI

(Credit: Kramer Electronics)

A couple months back I attempted to test two 30-inch displays--the Samsung SyncMaster 305T and the Gateway XHD3000 Extreme HD-- at the same time using CNET Labs' current distribution amplifier (DA), the Extron Electronics D2 DA4 DVI D2 DA4 DVI. This device allows up to four displays to simultaneously view the same video signal from one system. For years we've used this device to not only speed up testing, but to do accurate direct comparisons as well. Unfortunately the native resolution for the aforementioned 30-inchers is 2,560x1,600, and the maximum resolution the Extron supports is only 1,920x1,200. So, without a means to test them simultaneously at their native resolutions I was stuck in a bind. I could have tested them one at a time, but since our testing--which includes DisplayMate--has a high level of subjectivity to it, it's always best to do direct simultaneous comparisons, instead of testing one display today and then waiting a couple days to test the next. Testing them simultaneously allows you to see the exact differences between the displays.

So I delayed the testing and the review for a few weeks. In the meantime I got in touch with a colleague at DisplayMate, Ray Soneira. He put me in contact with a company called Kramer. Kramer manufactures a number of distribution amplifiers including the Kramer VM-2DVI. This particular DA is Dual Link compatible and supports each 30-inch display's 2560x1600 resolution. So now I could test both 30-inch displays simultaneously at their native resolutions in DisplayMate and in our current games test, World of Warcraft. However whenever I attempted to run either our Kill Bill Vol. 1 DVD or our Swordfish BD on both displays at the same time, the DRM gods reared their ugly heads and denied me salvation. So when testing how each display handles disc-based movies, I was forced to evaluate each display one at a time. The Kramer VM-2DVI is not advanced enough to circumvent DRM tomfoolery, unfortunately. That said, we're still very pleased that the VM-2DVI allowed us to do the bulk of our testing as fairly and accurately as possible.

The issue of not being able to view certain disc-based movies simultaneously on two or more displays may not be an issue for long, as CNET Labs is considering moving away from using movies--and even games-- to evaluate the quality of a display. The reason being that video images generally move too quickly to do a picture quality comparison, whereas static images such as high-quality photos can be studied as long as necessary in order to examine their quality. No decision has been made as yet, though, but look for more on this in a future Inside CNET Labs post. ... Read more