The Imagon

However, aperture provides very primitive control of the glow surrounding highlights. Stopping down the lens reduces both the radius and density of the area of glow. The Imagon uses an interesting approach to independently control the radius and density of the glow. This allows for the very desirable effect of having a moderately sharp image with highlights that are surrounded by a somewhat wide but very subtle glow.

Achieving this result is surprisingly straightforward. Instead of using a standard aperture with a single central opening, the Imagon combines a simple 2 element achromat with a set of unusual aperture disks. These disks have the usual circular opening surrounded by two rows of smaller holes. In this way, the majority of the light reaching the focal plane will have passed though the center of the lens via the large central opening. This causes the image to be moderately sharp. In addition, a smaller amount of light will have passed though the outer part of the lens via the small outer holes. This allows a small amount of out of focus light to reach the focal plane and produce a wide subtle glow.

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