1. Parallax- Apparent displacement of an object due to change in the position of the observer.
2. Pentaprism-reverse images laterally and reflect them to the viewfinder.
3. Pellicle- A thin, partially reflective coating, as on a beam splitter or pellicle mirror.
4. Periscope- Instrument used to view objects that above the level of sight.
5. Aperture- An opening that limits the quantity of light that can enter an optical instrument.
6. Shutter- Exposes light to the film.
7. Exposure- The amount of light the film is exposed to.
8. Depth of Field- The distance between the nearest and furthest objects in focus by the camera lens.
9. F-stop- Setting of an adjustable lens aperture.
10. Focal Length-the distance between and object lens and its corresponding focal plane in a telescope.