Aperture
The wider the lens opening, the more light per frame; the depth of field decreases, so plan the focus.
Field of view
Use the lens calculator with the sensor size, the distance and the subject to choose the focal length.
Macro and microscopy
Insects, droplets and electronic components call for macro lenses or coupling to a microscope.
Long distance
Proving grounds, mining and aerospace use long-distance lenses.
Mounts
Each Phantom model has mount options; check the datasheet.