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When you need a little more accuracy for translucent shading, Theta can step up. It's another form of translucency, but with a bit of ray tracing accuracy added. It's also a borderline subsurface shader. It uses an Index of Refraction to control how light affects the back side of the object, and also lets you specify how much of a spread that light has. This makes it better suited to thicker objects, like candles or plastics. The amount of light that is visible through the object is based on the viewing angle as much as the lighting angle. If the object is directly between the camera and the light, it will be lit the brightest. As the viewing angle brings the object out of line, the illumination decreases. The range value can widen this area of visibility. Because of this viewing angle dependency, this shader is good for thin materials that would have a certain amount of forward scattering. Again, leaves will work ok for this, but one really good example would be dust on a windshield. If you ever looked through slightly dusty glass, into the sun, you'll get the idea. Even though the glass looks clean from other angle, when you're looking towards the sun through it, it's hard to see through all that brightly lit dust. Clear and translucent plastics, glass (great for frosted glass), and some liquids will make good use of this shader. It's also good for thin membranes, like bat wings, where you can have a texture plugged into the Color input of the shader, which will only show up in a specific viewing angle. Again, it's usually best to use this with another shader.