Thin Lens
Thin lens equation 1/F = 1/d + 1/f: image distance, focal length, optical power, magnification and image properties.
What to find:
Enter the focal length as a positive number and choose the lens type. A virtual image distance f is negative. A diverging lens has negative optical power.
The thin lens calculator finds the image distance, focal length, object distance, optical power and magnification, and describes the image: real or virtual, upright or inverted, magnified or reduced.
Thin lens equation
1/F = 1/d + 1/f, M = |f|/d, D = 1/F
Sign convention: F > 0 for a converging lens and F < 0 for a diverging one; f < 0 for a virtual image. Optical power D is in diopters (F in meters).
Images in a converging lens
| Object position | Image |
|---|---|
| d > 2F | real, inverted, reduced |
| d = 2F | real, inverted, same size |
| F < d < 2F | real, inverted, magnified |
| d = F | no image |
| d < F | virtual, upright, magnified (magnifier) |
A diverging lens always gives a virtual, upright, reduced image.
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