(a) Example image with a total exposure of ∼91 e− Å−2. Rotavirus DLPs from the data set used in this analysis, kindly shared by Dr Tim Grant. (b) Average SNR values as a function of total exposure. Solid black line: simple averaging of movie frames, no exposure filtering. Dashed black line: image summed from exposure weighted movie frames. Solid blue line: reference simulated with cumulative exposure filter as would normally be applied to a movie. Dashed blue line: both image and reference exposure filtered. Red square: maximum SNR attainable using a single B-factor to represent all envelopes. Scale bar 500 Å.