What is diffraction in photography?

When light passes through a small aperture, it diffracts — bending around the edges and spreading into a circular blur pattern called an Airy disk. As the aperture narrows (higher f-number), the Airy disk grows. When it exceeds the size of one or two pixels, fine detail is lost even if the focus is perfect.

What wavelength does this calculator use?

Green light at 550 nm, which is the peak sensitivity of most camera sensors and the wavelength used for standard photographic diffraction calculations. Real lenses capture a spectrum, so results are a practical approximation.

Why do higher-resolution cameras diffract at lower f-stops?

More pixels in the same sensor area means smaller pixels. A smaller pixel pitch is reached by the growing Airy disk at a wider aperture, so the diffraction limit hits earlier for high-resolution sensors.

Does this mean I should never use f/16 or f/22?

Not necessarily. The gain in depth of field can outweigh diffraction softening for many subjects. For maximum pixel-level sharpness — macro, studio, architectural detail — stay within the onset limit. For landscapes needing huge DOF, a little diffraction is an acceptable trade-off.

How do I find my pixel pitch?

Pixel pitch = sensor width (mm) / horizontal pixel count. For example, a full-frame sensor (36 mm wide) with 6000 horizontal pixels has a pitch of 36/6000 = 0.006 mm = 6 µm. Most manufacturer spec sheets list this directly.

Does lens quality affect the diffraction limit?

No. Diffraction is a fundamental wave-optics phenomenon independent of lens design. Even a perfect lens diffracts light. Lens aberrations matter at wide apertures; diffraction matters at narrow apertures.

Diffraction Limit Calculator for Photography

Enter your sensor resolution and pixel pitch to find the f-stop where diffraction softening first becomes visible and where it significantly degrades sharpness.

Camera Settings

Quick Preset

Or enter values manually:

Sensor Width (mm)

Sensor Height (mm)

Sensor Resolution (MP)

Wavelength (nm)

Green (550 nm) is the standard

Computed pixel pitch: —

Diffraction Onset

—

Airy disk = 1× pixel pitch

Softening begins to appear at 100% crop on screen.

Strong Softening

—

Airy disk = 2× pixel pitch

Visible in prints; avoid for maximum sharpness.

Pixel pitch detail

Pixel Pitch

—

µm

Horizontal px

—

Vertical px

—

Airy Disk vs. Pixel Size at Common F-Stops

F-stop	Airy disk (µm)	Impact
Enter sensor specs above

Summary

Diffraction occurs when light bends around the aperture blades, creating an Airy disk that grows larger as the aperture narrows. When the Airy disk diameter exceeds one or two pixels, fine detail starts to blur — even if everything is in focus. This calculator uses your sensor's pixel pitch and the wavelength of green light (550 nm) to compute the f-stop at which diffraction first becomes visible and the harder limit where softening is clearly apparent in prints.

How it works

Select a common camera preset or enter your sensor's megapixels and physical dimensions manually.
The pixel pitch is computed from sensor size divided by pixel count along each axis.
The diffraction-limited f-stop is calculated as pixel pitch divided by 2.44 times the wavelength of light (550 nm).
Two thresholds are shown: the onset f-stop (1× pixel pitch) and the strong-softening f-stop (2× pixel pitch).
A chart shows the Airy disk size relative to pixel pitch across a range of f-stops.
Use the results to choose the sweet spot aperture for maximum sharpness on your specific camera.

Use cases

Find the sharpest aperture range for landscape photography before diffraction starts degrading detail.
Compare how diffraction limits differ between a 24 MP full-frame and a 45 MP body.
Understand why very high-resolution cameras show diffraction at wider apertures than lower-resolution ones.
Plan astrophotography exposures that balance depth of field and diffraction softening.
Evaluate whether stopping down below f/11 makes sense for your specific sensor.
Teach students the optical physics behind the sharpest-aperture sweet spot.

Frequently Asked Questions

Last updated: 2026-06-15 · Reviewed by Nham Vu