Some of you may be familiar with Leica's R system. Though the system was certainly overshadowed by the M cameras, these lenses are some of the best that Leica ever made. I was first introduced to these lenses during my brief foray into the Sony mirrorless system. I picked up a 50mm f/2 R mount lens and it is likely the best 50mm that I have owned. It was sharp, small, smooth, and light. It could be the perfect 50mm. There is, however, another level to the Leica R madness.
Recently, I stumbled upon something entirely crazy. Cinema Glass is a company that will build you R series lenses rehoused as cinema lenses. This set will run you $25,000, and it includes the Leica R 19mm T/2.8, 28mm T/2.8, 35mm T/2, 50mm T/2, 90mm T/2, and 135mm T/2.8. For an extra $5,000, the T/2 lenses can be replaced with their T/1.4 variants. They even offer the ability to add the 15mm and 180mm primes into the set.
Many might ask why on earth would you do that. Well, for one, the Leica R lenses are among the best in the world. In many cases, they match or exceed the quality of the M series lenses. Because the R cameras dropped off of the map in the early 2000s, the desire for these lenses disappeared. But even with that in mind, why would you want a set of them rehoused into cinema lenses? It makes life easier for filmmaking. For one thing, the aperture ring is smooth. With no clicks, the aperture can be adjusted mid-shot without the obvious, bumpy change in exposure. The focus ring and the aperture ring also have gearing on them, allowing you to pull focus with a follow focus system. And on top of that, the focus throw is expanded to 120 degrees and can be expanded further (for a fee) to 300 degrees to allow for extremely precise focus and smooth transitions as focus racks through a shot. The filter size is also made to be 95mm, and while a large size, it is matched throughout the set to allow for one filter system to be used on all of the lenses. It also means that your camera rig won't need to be readjusted when you switch to a different size lens. The mount is converted to PL as well for easy use on RED, Arri, and other high-end cinema cameras. 
The real kicker is that this set is still well under the price of many other high-end cinema lens sets. What do you think? Have you used Leica R lenses? Would you rather go with these or the new Rokinon Xeen series or Zeiss Compact Primes? I am certainly intrigued by this set and believe that they would be real stunners on any camera.
I have a set of these Leica R T2's from GL Optics/Cinema Glass. I've used plenty of rehoused lenses in the past (P&S Technik and Duclos) and these by far are the best I've ever used! The lenses are hand-picked and each set matches, and the R's are all v3 so they preform even better then the older R's.
The lens build is solid, focus marks accurate, even wider focus throw-except the 19mm :( , and it's Leica Rs-they're literally in a league of their own: not quite vintage but super sharp even giving today's modern lenses/coatings a run for their money. Always loved the Leica R look, so much character and much more flattering to me then the uber clean and pristine look we get from today's optics.
I definitely recommend these lenses if your budget allows... You'll be glad you did! They also recently renting them if anyone would rather choose that route: https://rentcinemaglass.com/product-category/lens-sets/
I used leica R lenses on my d800 and the look, especially the colors are outstanding. but I'm too dumb to focus them, nail the focus when I'm doing people photos. what a pitty.
R Lenses on the Leica SL are a joy to use. I have four of them (50/90/180/35-70) and with that lovely viewfinder, they are easy as pie to focus manually.
Duclos does the cinema conversion of R series stills lenses for around $1000,- per lens, depending on what condition they are in. Been using R series lenses for a while now on both my stills and film work and they are absolutely amazing. The 60mm Macro is an absolute beast of a lens and probably my most used one.