This imaginative product comes with Fisheye Lenses and Filters: Vignetting and Dirt to make the perfect Bryce "lens" imperfect, and Effect Filters. Some objects are ready to use, and others need some adjusting - adhering to the Bryce tradition: make it easy for beginners and give the artist full control.
The point is this, bizarre though it may seem, to get a more realistic render it is sometimes necessary to degrade your image. The reasoning behind this is simple, we are used to accepting the imperfections of photographic images, indeed they have become such an inherent property of what we accept as "real" that lens flare in "realistic" video games it virtually ubiquitous. Don't just take my word for it, look at the images here and draw your own conclusions.