Hello

I have an imaging lens setup in Zemax, with Ray Aiming ON.

Often times I see lens examples given with a separate surface for the stop. Such a surface is planar (Radius INF), and positioned where a physical aperture like a shutter is installed.

My question is. Is there any unrealistic effects, or penalties. If I were to use a curved lens element as the stop. Assuming ray-aiming on.

What if I went further, and made the single stop surface in air(which is usually Planar like a shutter) have a radius of curvature. If allowed the radius to vary, the optimizer will usually end up picking a non-INF value which often gives better performance for abberrations in simulation. Is this curved stop surface realistic and usable? The surface remains just a circular aperture in air.