Its a dome shaped aperture.
Its benefit is to shorten the length of a lens. Here is the translated description of the benefit. A pancake is a good potential use.
Member x-vision is right-on!
"According to the present invention, a light volume adjustment suitable for a miniaturization is realizable. When a light volume regulation blade is especially opened to a release position in a light volume adjustment, in order that a light volume regulation blade may not take space to a radial direction, it becomes possible to miniaturize a light volume adjustment in a radial direction. And the miniaturization of the optical instrument which mounted this light volume adjustment can be attained. "
My dream of a 40mm f/1 cupcake is one step closer to reality!!!
Eos: 1Ds-III, 5D-III, 6D, 60D | Canon EF: TSE-24L-II, 16-35L-II, 24L-II, 35L, 40STM, 100f/2.8, 135L | Wishlist: TSE-17L, 200f/2L
Tamron: 24-70VC, 70-200VC, 150-600VC | Samyang: 8mm-T3.8, 14mm-T3.1
Crazy Ideas: TSE-90L-II, 40f/1, 100f/1.4, 35-85f/2, 100-300f/4_1.4xInt, 500f/5.6_1.4xInt