The camera frame rate is the speed at which frames can be acquired by the camera. High camera speed is necessary for capturing changes in dynamic imaging subjects, and for allowing high data throughput. Though, this high throughput does come with the potential downside of large amounts of data being produced by the camera. This can determine the type of interface used between the camera and the computer, and how much data storage and processing is required. In some cases, frame rate may be limited by the data rate of the interface used.
In most CMOS cameras, the frame rate is determined by the number of pixel rows active in the acquisition, which can be reduced by using a region of interest (ROI). Typically, the height of the ROI used and the maximum frame rate are inversely proportional - halving the number of pixel rows used doubles the frame rate of the camera - though this may not always be the case.
Some cameras have multiple ‘readout modes’, which typically allow a trade-off to be made in reducing dynamic range, in exchange for higher frame rates. For example, often scientific cameras may have a 16-bit ‘High Dynamic Range’ mode, with large dynamic range offering access to both low read noise and large full-well capacity. Also available might be a 12-bit ‘Standard’ or ‘Speed’ mode, which offers as much as double the frame rate, in exchange for reduced dynamic range, either through reduced full-well capacity for low-light imaging, or increased read noise for high-light applications where this is not a concern.