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Commonly known as bloom effect, Scattering occurs when the light is scattered inside the lens before reaching the film.
Note that the Scattering effect (as Diffraction as well) will be more visible the stronger the light source is. For example, if the camera sees the sun or a strong emitter, these will have a stronger scattering/diffraction effect. The Scattering and Diffraction effects (bloom and glare) will still be visible in the scene even if no direct light sources are seen by the camera, but the effect will be weaker.
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