Aye, good advice, but a sphere is NOT a lense. Take two spheres, offset them only a bit, on one axis. Boolean intersect the two, then parent and track this Grouping to the camera. Now you have a REAL fake lense! With this method, you can adjust the depth, and the refraction level on the lense, and simulate many real-lense-experiences. One can even produce truly Bryce-generated Lense Flare this way, by tweaking the bump slightly, and the specularity of course! The only drawback to Brycean lenses is the render time increase, I suggest setting up the scene with the lense set to "Hidden" first, then rendering. And, make sure the TIR is set to at least 2, for the best results... To make it REALLY interesting, make TWO lenses, and put them inside a hollowed out cylinder. Boom! A telescope... If you need a quick example, let me know!