You can fake a lens flare with Photoshop or some other image editing packages, as well, in post-render image manipulation. If it's an animation, you can render it as image sequences and add the flare in photoshop one frame at a time, or you can use an effects package like AfterEffects.... Unfortunately, Carrara's renderer doesn't realize that the lightbulb it's seeing through the transparent object (or reflected in a reflictive object, either) should also cause a lensflare....