Circle of Confusion (CoC) Calculatorv1.0.0

Circle of Confusion (CoC) is the largest blur spot on a camera sensor that still appears sharp to the human eye in a final print or display. Determine the CoC value for any camera sensor to support depth of field calculations, hyperfocal tables, and acceptable sharpness thresholds. CoC values inform decisions about aperture selection, focusing technique, and print size limitations.

• Select your camera or sensor format from the Camera Preset dropdown. Presets cover full frame, APS-C (Nikon/Sony and Canon), APS-H, Micro Four Thirds, medium format, one-inch sensors, smartphones, and large format film.
• If your sensor is not listed, choose Custom Sensor Size and enter the Sensor Width and Sensor Height in millimeters. The diagonal computes automatically.
• Choose a Calculation Method. The Zeiss Formula divides the sensor diagonal by a standard divisor. The Custom Visual Acuity Method computes CoC from print size, viewing distance, and the resolving power of the human eye.
• For the Zeiss method, select a Divisor value. Use 1500 for the traditional standard, 1730 for stricter digital sharpness criteria, or 1000 for a more lenient threshold. Custom divisors are also accepted.
• For the custom method, enter Viewing Distance, Print Width, Print Height in millimeters, and Visual Acuity in line pairs per millimeter. The standard 5 lp/mm at 250 mm corresponds to 20/20 vision.
• Results update automatically as you type. CoC displays in millimeters, microns, and inches. Click Show step-by-step derivation to see the full formula breakdown with your input values substituted.
• Input fields accept decimals (0.75), fractions (3/4), and mixed numbers (5 1/16). Settings are saved automatically and restored on return. Share calculations by bookmarking the URL with query parameters.

The circle of confusion is a foundational optical parameter used across photography, cinematography, optical engineering, and print production. Knowing the correct CoC for your specific camera and output medium ensures that depth of field calculations, hyperfocal tables, and sharpness evaluations are accurate rather than based on generic assumptions.

• Landscape Photography: Calculate the precise CoC for your camera to determine the true hyperfocal distance. A full frame sensor at 0.029 mm yields a different hyperfocal distance than the rounded 0.030 mm, which matters for sharp foreground-to-infinity compositions.
• Portrait Photography: Compare the CoC of a full frame camera (0.029 mm) with an APS-C body (0.019 mm) to understand why larger sensors produce shallower apparent depth of field at equivalent fields of view.
• Large Format Film: Compute CoC for 4x5 or 8x10 sheet film where 35mm values do not apply. A 4x5 camera has a CoC near 0.109 mm, changing depth of field behavior and requiring different aperture strategies.
• Print Production: Use the custom visual acuity method to determine CoC for actual output conditions. A billboard viewed from 3 meters tolerates a much larger CoC than a gallery print viewed from 250 mm, allowing wider apertures without visible blur.
• Cinematography: Determine CoC for cinema camera sensors such as Super 35 or full frame cinema formats. Accurate CoC values are critical for focus pulling and depth of field preview on set.
• Optical Engineering: Evaluate sharpness criteria for lens design and testing. Different divisor values (1500, 1730, or custom) represent different sharpness standards used in MTF analysis and lens quality evaluation.
• Smartphone Photography: Calculate the very small CoC of compact smartphone sensors to understand why smartphones have inherently deep depth of field and why computational bokeh is necessary to simulate shallow focus effects.
• Education: Teach students how sensor size, print magnification, viewing distance, and visual acuity interact to define acceptable sharpness. The step-by-step derivation shows how each variable contributes to the final CoC value.