Crazy

The Muse is the latest version of original Lensbaby. It uses the same glasses as the Composer. It's pretty hard to control the results, but a lot of fun to use.

The Composer is the "advanced" Lensbaby with better control. It's still a very odd lens with it's warped sharpness and exchangeable glasses.

My first ever fisheye lens, and a great performer. Both the mechanics and the optical quality is good, and the lens produces a stunning 180 degree vista on a full frame body

A tilt&shift lens that you can pay. It's very well built, but fully manual - both focus and aperture. It does the job both of correcting perspecive, creating large DOF when tilting the focal plane and doing fake miniatures when tilting the opposite way.

A fisheye is a great supplement to any lens lineup, and for Nikon DX owners this is the ticket. It's not cheap, but not extremely expensive either, and the quality of the mechanics as well as the resulting images are top notch.