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Calculators / Science / Thin lens image distance
Thin lens image distance calculator
Use the thin-lens equation to find signed image distance and magnification; a negative image distance represents a virtual image.
On this page
Image distance15cm
Magnification-0.5
Calculator controls
How to calculate
Use the thin-lens equation to find signed image distance and magnification; a negative image distance represents a virtual image.
Image distance = f*d/(d-f) cm; Magnification = -f/(d-f)
Worked example
Focal length (cm): 10; Object distance (cm): 30.
Image distance: 15 cm; Magnification: -0.5 .
Assumptions and limits
Use the thin-lens equation to find signed image distance and magnification; a negative image distance represents a virtual image. Thin-lens approximation with a real object. Positive focal length is converging; negative image distance is virtual. Negative magnification means an inverted image.
Results are rounded for display; calculations use unrounded values. Read our calculation methodology.
Understanding the result
Use the thin-lens equation to find signed image distance and magnification; a negative image distance represents a virtual image.
When this tool is useful
Image distance = f*d/(d-f) cm; Magnification = -f/(d-f)
Understanding your inputs
| Input | What to enter |
|---|---|
| Focal length (cm) | Enter a number of at least -1000000000000 and no more than 1000000000000. |
| Object distance (cm) | Enter a number of at least 1e-12 and no more than 1000000000000. |
Frequently asked questions
What assumptions does this calculation use?
Use the thin-lens equation to find signed image distance and magnification; a negative image distance represents a virtual image. Thin-lens approximation with a real object. Positive focal length is converging; negative image distance is virtual. Negative magnification means an inverted image.
How is the result calculated?
Image distance = f*d/(d-f) cm; Magnification = -f/(d-f)