Lens Diffraction Calculator

Formula

The formula to calculate the diffraction limit of a lens is:

$DL = 2 \cdot \lambda \cdot 1000 \cdot \sqrt{1 + A^2}$

Where:

$DL$ is the diffraction limit (micrometers).
$\lambda$ is the wavelength of light (micrometers).
$A$ is the aperture (f-stop).

Example

Let's say the wavelength ( $\lambda$ ) is 0.5 micrometers and the aperture ( $A$ ) is 2. Using the formula:

$DL = 2 \cdot 0.5 \cdot 1000 \cdot \sqrt{1 + 2^2}$

We get:

$DL = 1 \cdot 1000 \cdot \sqrt{5} \approx 2236.07 \text{ micrometers}$

So, the diffraction limit ( $DL$ ) is approximately 2236.07 micrometers.

What is Lens Diffraction?

Lens diffraction is a phenomenon that occurs when light waves encounter an obstacle or aperture, such as the blades of a camera lens. As light passes through a small aperture, it spreads out, causing the image to lose sharpness. This effect limits the resolution of the lens and is most noticeable at small apertures (high f-stop numbers). Understanding the diffraction limit helps photographers and optical engineers optimize image quality by balancing aperture size and the resulting depth of field with the sharpness of the image.