Extended Data Figure 6.
Doming models describing per-frame, spatially resolved (3x3 points) defocus offsets fitted during the refinement of atomic-resolution data of apoferritin (EMPIAR-10248) were averaged across the dataset, showing significant changes in the CTF during exposure.
(a) Defocus change plotted against the accumulated exposure show a fast change in both the central point and the average of the entire field of view’s 3x3 points at the beginning of the exposure. After the first 7.5e-/Å2 of exposure, the average change stabilizes, while the central point continues to decrease in defocus.
(b) When corrected for global inclination, the difference between the central and peripheral defocus change indicates a steady increase in doming within the field of view as a function of accumulated exposure.
(c) Surface rendering of the spatially resolved defocus change for the first 7 frames shows an inclination of the entire field of view, as well as a more localized dent in the center. The observed change in the CTF can also be caused by electrostatic lensing effects due to sample charging, and further experiments are necessary to investigate the exact nature of doming.