Classical photogrammetry usually assumes that the entire image is sharp. However, when reconstructing tiny objects using macro lenses or microscopes, resolution is limited by depth of field (for large apertures) and diffraction (for small apertures). This creates challenges both for instrument calibration, but also for finding correspondences and other aspects of reconstrction from images.

See also:

X.Weng, M.She, D.Nakath, K.Köser:
MaCal: Macro Lens Calibration and the Focus Stack Camera Model.
International Conference on 3D Vision (3DV). IEEE, 2021
doi: 10.1109/3DV53792.2021.00024
[Presentation Video] [Preprint Version]