10.8.2 Aperture Shape

Aperture Shape sub-section in the Iray section of the camera Attribute Editor
Iray for Maya now supports three different shapes for the aperture shape: Circular, Blade and Custom. The aperture shape becomes visible when looking into a light source or very bright highlights.
The aperture shape is only visible when Depth of Field is turned on in the Attribute Editor of the same camera where Aperture Shape is turn on.
Type Circular
 The aperture shape is set to a circular shape.
Type Blade
The aperture shape is set to a n-sided polygonal shape.
GUI when Aperture Shape Blade is selected
When Type is set to Blade the following attributes are available:
Sets the number of edges of the n-sided polygon.
Blade Rotation Angle
Sets the rotation of the n-sided polygonal aperture shape.
Type Texture
Use a texture image to define the aperture shape.
This feature is not recognize by the IPR. You need to restart the rendering to see the texture create an effect.