How much impact do chromatic aberrations in lenses have on the value of CCTV video streams?
A: The impact of chromatic aberration depends on angle of view – it has more negative impact in wide scenes – it’s also more damaging if you need depth of the field to cover a large open space. Some lenses will only show CAs at the edges of the scene – other lenses have latitudinal and longitudinal CAs wherever there are high contrast borders.
Sometimes CAs from a fast lens are acceptable if you’re also getting excellent low light performance. It’s when you’re zooming in from a distance or using digital zoom to identify features and license plates that CAs of 3-10 pixels wide begin ruining camera performance. CAs in a PTZ lens can have a major impact at the long end.
CAs are caused by different wavelengths of light being focused in different planes and are a symptom of poor lens design. They may occur in internal or external applications. Severe chromatic aberration will soften images in the presence of significant backlight or reflected light.
You can improve CAs by stopping down (using a longer focal length reduces aperture), changing the angle of view to remove the high contrast areas, or buying higher quality lenses with improved optical equations. Some lenses and some camera brands are especially susceptible to CAs – even in top shelf gear. If the lens is not crazy fast it means the manufacturer is economizing in the lens department, often with use of plastic elements.
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