This calculator helps you determine the diffraction limit of your camera system.
That is, it estimates the limits of any lens attached to a camera at a given aperture and with a set
contrast threshold. A contrast threshold of 0% means there is no difference between light and dark objects,
while a higher percentage means a more noticeable difference is visible. This means the absolute limit
of resolution is at 0%, but in practice a threshold of about 20% is often used.
Note that a wavelength of 520 nm (green light) is used by default,
this is due to it being in the middle of the visible spectrum and a reasonable choice for general photography.
This is a fundamental physical limit that only depends on the aperture, contrast threshold, and wavelength of light.
| Aperture |
|
| Contrast Threshold |
|
| Absolute Max Resolution* (lp/mm) |
|
| Threshold Resolution (lp/mm) |
|
* Absolute Max Resolution corresponds to a contrast threshold of 0%.
Determine if your sensor is diffraction limited
To determine if your sensor is diffraction limited, you can calculate the pixel pitch of your sensor and compare it to the diffraction limit calculated above. The pixel pitch is the distance between the centers of two adjacent pixels on your sensor, and it can be calculated using the following formula:
Pixel Pitch (mm) = Sensor Size (mm) / Pixel Count
According to the Nyquist-Shannon sampling theorem, the maximum resolvable frequency is half the sampling rate. In imaging, one "Line Pair" (one black line + one white line) requires a minimum of 2 pixels to be resolved. Therefore, the Nyquist frequency can be calculated as:
Nyquist Frequency (lp/mm) = Pixel Pitch (mm) / 2
If the diffraction limit is smaller than the Nyquist frequency, then your sensor is diffraction limited at that aperture and contrast threshold. This means that the limiting factor is the physics of light rather than the sensor's ability to capture detail or lens' performance.