Jointly designing computational signal extraction and optics allows scalability to larger fields-of-view, lighter and faster functional neuroimaging devices. Using this insight, we developed a modular, mesoscale light field (MesoLF) imaging hardware and software solution (Nature Methods 20(4), 2023) that allows recording from thousands of neurons within volumes of ⌀ 4 × 0.2 mm located at depths of up to 350 μm in the mouse cortex. MesoLF achieves an imaging rate of 18 volumes per second and an effective voxel rate of approximately 40 Megavoxels per second. By using our optical design and computational approach, we were able to record activity from approximately 10,000 neurons across multiple cortical areas in mice, using only workstation-grade computing resources.We also developed a miniature, head-mounted light field imaging device, MiniLFM v2.0, which allows functional imaging of thousands of neurons in a ⌀1 × 0.2 mm volumetric field-of-view at 20 Hz and up to a depth of ~380 μm. Our lightweight and small device offers a large ~1.2 mm working distance, incorporates an electrically tunable focus and allows half-hour long imaging sessions in freely moving mice. It allows imaging population-level neuronal activity in unrestrained animals, which has emerged as a key technique enabling the study of neural coding, processing and learning during unrestrained, naturalistic behaviors. ​Together, MesoLF and MiniLFM demonstrate the unique scalability and flexibility of light field microscopy.Research reported here was supported by the National Institutes of Health (5U01NS103488, 1RF1NS110501, 1RF1NS113251), the National Science Foundation (NSF-DBI-1707408) and the Kavli Foundation through the Kavli Neural System Institute.