Diffraction Calculator

Powered by Photopills, this diffraction calculator will allow you work out the effect of diffraction upon your image and whether your final use is likely to show the impact of diffraction.

How To Use

Set your camera model, megapixels and aperture to find out whether the resulting image will show signs of diffraction. There are two results, the first result is based on viewing at 100% on a screen. The second result is based on a 10x8 print with a relative viewing distance. Note: As the print size increases so does the viewing distance. This size print is therefor accepted as being relative to all sizes.

Understanding The Results

Airy Disk: The Airy Disk is the diffraction pattern formed by the scattering of light waves through the opening. The waves interact with each other, creating this pattern known as the Airy Disk. Measured in Macrons (one thousandth of a millimeter), it’s diameter is compared to the size of the Pixels (100% Crop) or to the diameter of the Circle Of Confusion (print).

Pixel Size: The size of the pixels upon the camera sensor in macrons. Where the Airy Disk has a diameter of greater than 2.5x the Pixel Size, it is assumed that diffraction will start to become a noticable factor in pixel ‘sharpness’

Circle Of Confusion: A measurement of the maximum size a ‘blur spot’ will still be interpreted by the viewer as a single point (sharp). This assumes standard viewing conditions and average viewer visual acuity. Should the Airy Disk diameter be smaller that the diameter of the Circle Of Confusion, the assumption is that it will appear as a ‘sharp’ point to the viewer.

Diffraction Limit: The aperture that may start to show the imapact of diffraction in the final image.