Diffraction Calculator

Diffraction is an optical phenomenon that limits the sharpness of photographs taken at small apertures. As a lens stops down to higher f-numbers, the Airy disk produced by light passing through the aperture grows larger. When the Airy disk exceeds the size of individual pixels on the sensor, the image begins to lose detail to diffraction softening, and that threshold is specific to each camera and lens combination.

• Camera presets or a custom sensor width, height, and megapixel value set the pixel geometry the calculation depends on; inputs accept fractions (3/4), mixed numbers (5 1/16), and decimals.
• Aperture is entered as an f-number, such as 8 for f/8 or 16 for f/16.
• Results report pixel pitch, the physical size of each pixel; Airy disk diameter, the size of the diffraction pattern; and diffraction status, whether the chosen aperture is diffraction-limited.
• The diffraction-limited aperture is the widest aperture at which diffraction begins to affect sharpness for the given sensor.
• Light wavelength defaults to 550 nm (green light) and can be adjusted, along with the diffraction criterion strictness, and a step-by-step formula display is also available.
• A diffraction-by-aperture table shows Airy disk sizes across a range of common apertures for a quick comparison of diffraction impact at different settings.

Understanding diffraction limits is essential for photographers, optical engineers, and anyone who needs to maximize image sharpness. Knowing the sharpest usable aperture for a specific body and lens prevents unnecessary loss of resolution and informs decisions about depth of field versus diffraction trade-offs.

• Landscape Photography: Determine the optimal aperture for maximum depth of field without crossing the diffraction limit. A 45 MP full-frame camera becomes diffraction-limited at a wider aperture than a 12 MP model, making this calculation critical for high-resolution landscape work.
• Product Photography: Find the sharpest aperture when focus stacking is not an option. Small apertures used for depth of field should not sacrifice the fine detail needed for e-commerce product images.
• Macro Photography: Evaluate diffraction effects when shooting at very small apertures such as f/22 or f/32, which are commonly needed for sufficient depth of field at close focusing distances.
• Astrophotography: Adjusting the light wavelength setting evaluates diffraction for narrowband filters (such as H-alpha at 656 nm) and confirms whether aperture choice maintains resolving power at non-visible wavelengths.
• Camera Comparison: Compare different camera bodies to understand how pixel density affects the diffraction-limited aperture. Higher megapixel sensors have smaller pixels and become diffraction-limited sooner.
• Education: Visualize the relationship between aperture, wavelength, and pixel pitch through the step-by-step formula derivation. Diffraction is a fundamental optical limit, not a lens defect.
• Video Production: Assess whether stopping down for consistent exposure across a scene will degrade resolving power on 4K or 8K sensors where pixel pitch is small.