High sensitivity cameras can lower spatial resolution in high-resolution optical microscopy

High-resolution optical fluorescence microscopies and, in particular, super-resolution fluorescence microscopy, are rapidly adopting highly sensitive cameras as their referred photodetectors. Camera-based parallel detection facilitates high-speed live cell imaging with the highest spatial resolution. Here, we show that the drive to use ever more sensitive, photon-counting image sensors in cameras can, however, have detrimental effects on spatial resolution that many researchers are not aware of. Typical parameters which influence the selection of image sensors are pixel size, quantum efficiency, signal-to-noise performance, dynamic range, and frame rate of the sensor. A parameter that is, however, often overlooked, is the sensors modulation transfer function (MTF). We have determined the wavelength-specific MTF of front- and back-illuminated image sensors and evaluated how it affects the spatial resolution that can be achieved in high fluorescence microscopy modalities. We find significant differences in image sensor performance for sensors that cause the resulting spatial resolution to vary with up to 28%. This result shows that the choice of image sensor has significant impact on the imaging performance of all camera-based optical microscopy modalities.