DxO has issued a press release to photographic websites this morning containing two major announcements. First, "as early as next week," it will add measurement results for many new cameras—including some medium-format cameras.
Second, it has instituted a new "Questions & Answers" section at dxomark.com. This will be an ongoing service, but, naturally, some of the most basic and pressing questions have been answered in the first go-round (such as, "How is DxOMark Sensor computed? What is the formula?"). If you've been following the new website and have questions about how the evaluations are arrived at, you can get the answers straight from DxO.
Here are a couple of samples from the first round:
"How can I know if two cameras are noticeably different?"
Consider a digital gain of one f-stop, or similarly underexposing 1 EV at capture and then adding 1 EV at RAW conversion. This operation leads to a loss of 1 in Dynamic Range, 1.5 in Color Sensitivity, and 1 in log2 (Low-Light ISO), corresponding to a loss of 15 in DxOMark Sensor. Therefore, you can consider that a 15-point difference on the DxOMark Sensor scale is roughly equivalent to a difference of 1 f-stop, and that a difference of 5 is equivalent to 1/3 f-stop. DxO Mark Sensor differences below 5 can be considered as not noticeable.
"Should I interpret DxOMark Sensor results depending on the way I use a camera?"
Before evaluating a camera, you should indeed define your own photographic use-cases. The print size that you typically prefer will determine the minimal resolution that you need. Once you know your required resolution, then you can use DxOMark Sensor to look at the best digital camera within the resolution category that you have selected. If your main use case is to view pictures on screen at 1:1 scaling, then you are less concerned with resolution (so long as your screen has fewer pixels than your camera), which means that you can use the "Screen" measurement that dxomark.com provides.
Many more answers are provided at the website. As a gratuitous editorial comment, I'd just like to say that DxO is really to be applauded for providing this very valuable website and service—a perfect complement to sites that test cameras as integrated devices and don't attempt to isolate the quality of the sensor.
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