Manufacturer description: Introducing the Spark from Lensbaby, a fun and affordable way to capture selective focus images with a digital SLR. Spark features a unique selective focus optic and a tilting lens body, allowing the aspiring amateur photographer to capture creative images in-camera that have a sweet spot of focus, surrounded by blur. Spark is a lightweight, all plastic (except for the optic, which is a multi-coated glass doublet) 50mm selective focus lens with a f/5.6 fixed aperture available for Canon and Nikon DSLRs. Spark is the perfect entry point into the Lensbaby system for photography students or newer photographers looking to expand their experiment and add a creative lens to their camera bag. Spark is compatible with the rest of the optics in the Optic Swap System, and with all Lensbaby 37mm threaded accessory lenses.