Sony A900: A Closer Look at 24.6MP Resolution and Noise

Looking Forward

The Sony A900 is a truly revolutionary camera. As the highest resolution full-frame DSLR you can currently buy it distinguishes itself with astonishing resolution. As discussed in our preview it is also the first full-frame with body-integrated Image Stabilization (add 2 to 4 stops to hand held shooting) and the viewfinder is the best, brightest, sharpest that we have ever seen in a DSLR - or perhaps in any camera.

It is important to keep those huge pluses in perspective because image noise at extended ISOs, while just one factor in the total image quality equation, is definitely not a strength of the A900. Compared to the Nikon D700, noise in the A900 is about two stops worse. That means the D700 at ISO 6400 exhibits about the same noise as the A900 at ISO 1600. In the case of the D700 that applies to both the actual pixel comparisons as well as the double pixel samples downsized to reflect the same image view in both crops. Despite the huge noise advantage, the D700 outputs nothing near the resolution and detail of the A900, which should not come as a surprise.

The Canon 5D is now three years old, but noise control is still about a stop or two better than the A900. However, we noticed for the first time how much Canon softens images at higher ISOs in an effort to control noise. Looking at the pixel level, high ISO Canon images are extremely soft at higher ISO settings, though they are quite sharp in the lower ISOs most sites use in evaluating the 5D output. Taken in total the A900 is again a clear leader in detail compared to the 5D. The 5D has perhaps a one stop advantage in noise when the A900 and 5D are equalized for sharpness.

Finally we come to the biggest surprise of all, which is our comparison of the A900 noise to the APS-C sensor in the A700. This is the same sensor used in the Nikon D300 and the most recent Nikon D90. When the A700 was first released, some in the press trashed it because of its heavy-handed noise reduction techniques. Sony has worked hard to answer those complaints, and most users were pleased with the v3 firmware fixes. With the release of the A900 Sony also released a v4 firmware for the A700, which allows complete disabling of NR plus a range of adjustments in noise reduction. V4 incorporates in the A700 all Sony had learned in developing the A900.

With sensor density of the A900 less than the A900 (2.9 vs. 3.3) we really thought the A900 would shine compared to the A700. In fact the A700 is about two stops better in noise control looking at actual pixel crops and one to two stops better looking at crops equalized for image view (A900 down-sampled to equivalent 12MP). This performance difference is a complete surprise and it is either good news or bad news depending on your perspective. The bad news version is that the A900 sensor is inherently a high-noise sensor and the high ISO noise performance is as good as we will see. The good news version is that the A900 was just released and, like the A700, Sony will continue to improve the noise performance in future firmware/software releases. We certainly saw that in the A700, but we did have the Nikon D300 as the constant reminder of what that sensor was capable of.

Our hands-on test of the A900 reveals a mixed bag of performance. At Lower ISOs, 100-400, nothing on the market comes close to the Sony. A little is given up at 800-1600 and if that were as bad as it got the A900 would be something of a Holy Grail. However, noise at ISO 3200 and 6400 are truly not competitive. High detail is still there but it is seriously marred by high noise. In the end our expectation is that professionals will stick to ISO 100-400 for the highest resolution shots you can get from a camera in this class. Action shooters and the rest of us will also be happy with ISO 800 and 1600. However, dial in above ISO 1600 only if you will be happy with stunning detail in smaller prints.

The last page contains a few sample images taken in the couple of weeks the Sony A900 has been in the office. As always, we chose the images to show both the strengths and weaknesses of the camera we are testing. The A900 is capable of capturing amazing detail and if you do a lot of pixel-peeping on these images you will see exactly what we mean. There are also a couple of shots that show the potential impact of poor noise performance at higher ISO, which is not always as bad as it sounds.

The Sony A900 will likely be long remembered for its record-setting resolution and its utility as a camera that is a true working tool instead of an amalgam of gadgets. The stunning 100% viewfinder is one example of that, but so is the logical and simple control that is a part of every aspect of the A900. It is not without its flaws but in total the A900 is definitely greater than the sum of its parts or any one area of measured performance.