Unit 1.4 Flashcards
1
Q
What is the optical center of a lens?
A
A point, usually but not always, within a lens, at which the rays of light from two sources entering the lens are assumed to cross.
2
Q
What unit is normally used to express focal length?
A
Millimeters
3
Q
What two factors determine the speed of a lens?
A
- The focal length
2. The diameter of the aperture opening
