Lens Reviews Explained
DxOMark is the trusted industry standard for camera and lens independent image quality measurements and ratings. For years, DxOMark has established its reputation for the best:
- Rigorous hardware testing
- Industry-grade laboratory tools
- Database of thousands of camera-lens test results
DxOMark consists of a comprehensive RAW-based image quality measurement database and a set of scores used to evaluate and compare digital cameras and lenses.
A unique Measurement Database
All measurements are performed on straight-from-camera RAW files, the only reliable way to evaluate intrinsic hardware performance. All lenses are tested on every camera on which they can be mounted as camera sensors impact the optical performance of lenses.
Lenses and cameras are tested for their full range of possible settings such as focal length, aperture, exposure time, ISO speed, white balance, etc. To ensure highest precision and reliability, measurements are performed at DxO Labs’ dedicated testing laboratories, where conditions are controlled as in standard metrology labs.
To ensure that measurements for all lenses and cameras can be reliably compared, DxOMark has developed detailed protocols that are systematically repeated for all equipment which are tested. These protocols are detailed on the DxOMark’s website, so that anyone interested in performing measurements can do so.
DxOMark test commercial products: in other words, DxOMark buy or rent lenses and cameras from the very same retailers that consumers use. When DxOMark do test pre-production models (when commercial products are not yet available), DxOMark clearly indicate this on its site, and retest those models when they become commercially available. Finally, DxOMark has no ties to or interests of any sort with camera or lens manufacturers, which means that DxOMark is completely independent from them.
DxOMark Scores for ranking and comparison of cameras and lenses
The DxOMark Measurement Database is so large and exhaustive that comparing or selecting camera or lens for specific needs could prove difficult without appropriate tools. Accordingly, DxOMark have defined a set of fifteen DxOMark Scores to facilitate easy ranking and sorting.
The DxOMark Scores are designed based on the following photographic use cases: Portrait, Landscape, and Sport.
To design DxOMark Scores, DxOMark have made choices about photographic use cases and their associated image quality requirements (such as resolution, distortion, noise, dynamic range, etc.).
DxOMark means objective, independent, comprehensive image quality data
DxOMark measurements are performed on unprocessed RAW files, prior to any digital image processing (except processing that may happen on the sensor chip itself). RAW format is the format by which objective performance for digital cameras is most effectively evaluated, as it does not depend on the efficiency of the RAW conversion applied. RAW is also intrinsically more relevant for measuring lens performance, given that no further processing was used that might have smoothed or hidden any intrinsic optical limitations or lens defects.
DxOMark lens measurements are unique in that they are performed on RAW and are specific to all camera bodies for which each lens is designed. The test results published on dxomark.com conclusively show that the same lens performs differently when mounted on different camera bodies.
Many sensor characteristics, such as physical size, pixel pitch, and microlenses, influence the optical performance of lens/camera combinations.
DxOMark perform measurements for each lens-camera combination using a wide range of shooting parameters (aperture, ISO speed, object distance, focal length, etc). Up to a thousand shots of various targets under different exposure conditions may be required for each combination; generating hundreds of thousands of measurement data reflecting lens performance.
DxOMark measurement methods and protocols are open and compliant with international and industry standards
All measurements follow the methods and protocols described in ISO (International Standard Organization) standard documentation or developed by industry players and considered as industry standards. DxO Labs image scientists and engineers have studied, developed, and implemented such standard methods and protocols and then packaged these tools and know-how in a commercial solution, DxO Analyzer.
DxO Analyzer is now used in the digital camera and component industry worldwide by such manufacturers as Nikon, Olympus, Panasonic and Samsung, to name just a few. DxO Analyzer is also used to perform certain tests by many web and print photo magazines, including Popular Photography, Nippon Camera, Chasseur d’Images, DIWA Labs, Imaging Resource, Réponse Photo, Let’s Go Digital, Digital Camera Magazine Japan, digitalkamera.de, and more than 30 other press partners.
Further, DxO Labs has put in place a very thorough data validation process. Once data are produced, they are analyzed in detail and compared with those in existing image quality measurements database (thousands of digital cameras, lenses and imaging systems have been tested and analyzed over time). This process has led DxOMark to develop specific protocols or tools to deal with difficult measurement issues such as best focus optical performance and sensor spectral sensitivity.
DxO Labs is an active participant in international imaging standardization activities. For example, it has been elected as Technical Editor of the International Imaging Industry Association (I3A) CPIQ standard for defining new methods to assess photographic quality from the consumer point of view, and DxO Labs image scientists regularly present their results at such renowned digital imaging conferences as the Electronic Imaging Conference, and Image Sensors (Europe and US).
To learn more, visit the official DxO Labs website.
The views and opinions expressed in this article are those of the author and do not necessarily reflect the views and opinions held by dpreview.com or any affiliated companies.