Thin Lens Image Distance Calculator
Solves the thin-lens equation for image distance. Changing an input recalculates the output without hiding the substitution.
State the optical convention
Image distance
Test the optical relationship independently
Reduce the dimensions in di = 1 / (1/f − 1/do) until they agree with m. For logarithms, trigonometric functions, and ratios, also verify that their arguments are dimensionless and inside the permitted domain.
Change one source value slightly and predict the direction of image distance first. If the screen moves the other way, revisit the equation, signs, and reference frame.
From measured pattern to optical value
Solves the thin-lens equation for image distance. The calculation keeps focal length, object distance visible and reports image distance in m.
A negative result can identify a virtual image under the stated sign convention rather than a failed calculation.
The thin lens image distance page labels each value before it enters the equation. That prevents an angle convention, temperature scale, optical sign, or reference quantity from becoming an invisible assumption.
Following di = 1 / (1/f − 1/do)
For thin lens image distance, identify image distance as the sought quantity and copy the printed relationship before using the sample data. This establishes an auditable direction for the arithmetic.
Evaluate di = 1 / (1/f − 1/do) only after checking which values are ratios, absolute temperatures, signed distances, or dimensional measurements.
Conditions behind image distance
The thin lens image distance relationship uses paraxial rays or an ideal interference geometry. Thick elements, aberrations, polarization, dispersion, and large angles may require a more complete optical model for image distance.
Changing the medium, geometry, or reference frame may require a different relation than the one used for thin lens image distance.
Using image distance beyond this page
Distinguish computational digits from measured accuracy when storing the thin lens image distance result.
Record the operating condition, formula, units, and convention beside image distance. Those details distinguish a physically reproducible answer from a number copied out of context.
Choose the next unknown after Thin Lens Image Distance
The next unknown may be handled by thin lens focal length calculator and optical magnification calculator.
Preserve the system boundary and conventions when carrying image distance into another calculation.
Before using image distance
What does image distance represent?
It is the value of di = 1 / (1/f − 1/do) under the units, field meanings, and optics assumptions printed on the thin lens image distance page.
How can image distance be checked?
Rearrange di = 1 / (1/f − 1/do) to recover an entered value, reduce the surviving unit to m, and compare the scale with the physical setup.
Do the displayed units matter?
Yes. Convert each measurement to the unit beside its field before evaluating the thin lens image distance relationship.
Why might another image distance differ?
Another medium, temperature, geometry, reference frame, boundary condition, or sign convention can change the reported image distance.