Lensbaby's standard optics approximate a "normal" lens on most DSLRs. Often, that field of view just isn't wide enough. so the company offers several choices for those desiring a wider lens. Its most extreme offering is the Super Wide Angle Conversion Lens. This optic converts the Lensbaby Composer (or any of the company's earlier lenses, although you'll need a special adapter to use it on the original Lensbaby) from a 50mm equivalent to a 21mm focal length. This add on lens also close focuses letting you position it as close as 2.75" from the front of the lens to your subject. Just like the company's other add on lenses, the Super Wide Angle Conversion Lens screws into the front of the main Lensbaby lens. The add-on lens weighs 2.4 ounces and minimizes vignetting unless the Lensbaby is tilted to extreme (how "extreme" depends on whether you're using it with a full frame sensor or not). Any add-on conversion lens will cause vignetting under such circumstances though. The Lensbaby Super Wide Angle Conversion Lens doesn't produce any vignetting when the Lensbaby is oriented straight ahead.