If you zoom in on those photos, you can see that the camera images entire lines of text at the same resolution. A camera can 'read' the entire chart in one snapshot.
The eye doesn't work that way. For example, it is anisotropic in resolution; at the fovea, it has more 'pixels', but away from it, it has way fewer. Effect? You cannot read a line from a Snellen chart without moving your eyes. The eye doesn't take snapshots.
If you zoom in on those photos, you can see that the camera images entire lines of text at the same resolution. A camera can 'read' the entire chart in one snapshot.
The eye doesn't work that way. For example, it is anisotropic in resolution; at the fovea, it has more 'pixels', but away from it, it has way fewer. Effect? You cannot read a line from a Snellen chart without moving your eyes. The eye doesn't take snapshots.