Lens Optics

Drag the object (arrow) — watch real/virtual images form through converging and diverging lenses

f = 150px | u = -300px | v = 300px | m = -1.00 | Real, inverted image

focal length: 100px object height: 40px

show: focal points guide lines

The thin lens equation 1/v − 1/u = 1/f relates object distance u, image distance v, and focal length f. A converging lens (f > 0) forms real inverted images for |u| > f, virtual upright images for |u| < f. A diverging lens (f < 0) always forms virtual upright images.