We present a new method for measuring a camera’s Dynamic Range (DR) and low light performance, both of which are derived from C4 information capacity, which is measured directly from ISO 12233-standard 4:1 contrast slanted edges. The method uses a new test chart that consists of groups of squares in a compact arrangement, where each square differs in transmittance or reflectance from its neighbors by a factor of 4, so that all edges between adjacent squares in a group have 4:1 contrast ratio (a density step of 0.602). The major advantage of C4 is that it completely characterizes the performance of cameras for objects with 4:1 contrast, whereas the traditional metrics, signal amplitude, sharpness, and noise, each of which contributes to information capacity, do not individually constitute complete camera performance metrics. Because the new technique uses the difference in Digital Numbers (DNs) across an edge as the signal for calculating C4, it avoids a measurement issue with simple flat patches, where stray light can be misinterpreted as improved Signal-to-Noise Ratio (SNR), distorting the measurements. It does, however, require that the test chart be well-focused. (The old technique was tolerant of moderate misfocus.) Finally, we examine a new plot of C4 as a function of exposure, which is a superior representation of camera performance over a wide range of illumination.