The Neptune Convertible Art Lens System is designed to recreate a vintage look without being completely terrible wide-open like the old C-mount trash glass you keep buying on eBay.
The Neptune Convertible Art Lens System consists of a lens base that's mounted to your camera and several convertible lens components. By interchanging the front components, you can shoot photos or videos at three different fixed focal lengths — 35mm, 50mm and 80mm. An Art Lens System unlike any other; it offers you all the freedom of a zoom lens without compromising on prime lens quality, and it's the only convertible Art Lens out there to work with a range of modern-day analogue and digital cameras. Each component is assembled by using the finest multi-coated glass and crafted to produce exceptionally sharp focus and strong, saturated colors for stunning high-definition images — even when you're shooting close-ups at 0.25m/9.8" with Thalassa (35mm), 0.4/15.7" with Despina (50mm) or 0.8m/31.5" with Proteus (80mm). This is an Art Lens System that lets you take beautifully intimate shots, allowing you to get near enough to capture every last detail of your subject. And because it's so small and lightweight design, you can take it with you everywhere.
That's $600 for a 35mm f/3.5, 50mm f/2.8 and 80mm f/4 set of very compact full-frame manual primes with drop-in aperture plates, natively mounted in Canon EF or Nikon F, with a custom adapter for whatever mount you got. "Compact" and "consistent" are the watchwords: on the photography sites, the old men of the mountain are all angrily pointing out that you can get the same results by attaching some ancient thriftstore artillery piece. (Though I do love the Fujian 35)