How to use the chromatic focal spread calculator
Estimate how much the focal length of a lens spreads across colours. Enter focal length, abbe number in the fields above; the focal length spread across visible spectrum, spread as a percentage of focal length are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “chromatic aberration”, “colour focus spread”, “lens colour fringing”, “calculate chromatic focal spread”, “find focal length spread across visible spectrum”.
Formula
Variables
- f — Focal length (mm)
- V — Abbe number
Worked example
With focal length = 100 mm, abbe number = 60, the calculator gives focal length spread across visible spectrum ≈ 1.666667 mm; spread as a percentage of focal length ≈ 1.666667 %.
Frequently asked questions
What is the chromatic focal spread calculator used for?
Estimate how much the focal length of a lens spreads across colours. It helps with questions such as “chromatic aberration”, “colour focus spread”, “lens colour fringing”.
What is the formula for the chromatic focal spread calculation?
Focal length spread across visible spectrum (mm) = f / V. Spread as a percentage of focal length (%) = 100 / V. Here f is focal length (mm), V is abbe number.
What inputs do I need for the chromatic focal spread calculator?
You need focal length in mm, abbe number. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the chromatic focal spread calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the chromatic focal spread result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.