For DSLR/mirrorless camera housings, you need to purchase one or more ports to match the lens(es) you’ll be using so be sure to build that expense into your budget. Wide-angle lenses are the mainstay of most underwater photographers and require a dome (curved) port to maintain the lens’ field-of-view and avoid vignetting. Also, you may need a port extension—a small add-on that fits between the port and the housing—to adjust the lens-to-port distance for different optics. While you can take close up images with wide-angle lenses, for the best macro shots you’ll need a macro lens and flat port. In addition to Backscatter.com, a retailer that specializes in underwater photo gear, manufacturer sites (see resources sidebar) offer guidance for configuring the perfect lens/port combination, as well as what focusing gear(s) you’ll need.