Circle of confusion: when imaging an object point, due to the aberration, its imaging beam can not converge at a point, forming a diffuse circular projection on the image plane, becoming a dispersion circle. If the distance between the lens and the image plane remains unchanged and the point light source is moved back and forth along the optical axis, the image formed on the image plane will become a circle with a certain diameter, which is called diffusion circle. It is also translated into diffusion circle, dispersion ring, astigmatism circle, blur circle and scattering disk. 0.030 mm is calculated as a reference, and the dispersion circle (COC) is 35 mm format. Choose focal length and 35mm dispersion circle to calculate the chaotic cycle of a digital camera. For a 35 mm size dispersion circle, the normal range is 0.025-0.035 mm. The dispersion standard of Leica ring is 35mm and the size is 0.025mm.
Actual lens focal length (mm): 32
Equivalent to 35mm focal length (mm): 35.5
35mm Dispersion circle size（mm）: 0.030
Diffusion circle of digital camera（mm）: 0.027
Calculation according to their own requirements, carefully choose the value, the diffusion circle of digital camera will automatically output the results.
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