Extended Data Fig. 1: A linear defocus ramp can compensate for errors in tilt axis offset.

a. Shown are defocus values estimated by CTF fitting for two tilt series collected on the same lamella using PACE-tomo. One tilt series was recorded without applying a defocus ramp (dashed line). The other tilt series (solid line) was recorded while applying a defocus ramp of 0.03 µm/degree. Outliers at extreme tilt angles were not considered for the linear fit of the defocus slope. b. Shown are defocus values estimated by CTF fitting for two tilt series collected on amorphous carbon support using PACE-tomo. One tilt series was recorded using the tilt axis offset determined by the fine eucentricity routine of SerialEM (dashed line). The other tilt series (solid line) was recorded using the tilt axis offset determined using the PACEtomo_measureOffset.py script.