As any Cinematographer will tell you, lenses are more important than your camera. Some time ago now, I was in the market for a set of high quality lenses for use with my work, but simply didn't have the cash to invest in a set of proper cinema lenses. Even 'budget' cinema glass such as the Zeiss CP.2s or the Canon CN-E primes were out of my price range.
Having already bought, used and sold many Canon L series lenses, I required more out of my lenses - something more suitable for cinema use as opposed to just stills. Optically, the Canon DSLR lenses are great and are reasonably affordable too - particularly when including their 'non-L' lenses. However, I had a list of pre-requisites that I wanted in my lenses and the Canons could not fulfil every criteria:
Optically sufficient; affordable; covers full frame; EF mount/fit; manual aperture; de-clicked aperture (or able to be) and correct focus direction.
Given that I was frequently using Canon 5DmkIII and on occasion, RED cameras, covering full frame became a necessity. And without limiting myself to just PL mount cameras, Canon's EF mount is the obvious, and certainly the most popular choice. Not only do Canon's C300/100 cameras (and their aforementioned DSLRs and REDs) sport an EF mount, but many other manufacturers such as Blackmagic Design offer EF mounts on their cameras or with the aid of adapters such as Metabones, EF lenses are compatible with other cameras such as those from Sony.
The criteria narrow down my options considerably, and a few options presented themselves.
Samyang produce a range of all manual stills lenses, and along side which, 'cine' versions of each. The only difference being the aperture is de-clicked and marked in T-stops and both aperture and focus rings are geared for use with follow focus devices. They tick every box, and whilst 'optically sufficient' is a subjective criteria, I know there are plenty of alternatives out there that far surpass the Samyangs. Since my initial search for a set of lenses a couple of years ago, Samyang have released a 'proper' set of cinema lenses called Xeen, in large metal bodies, long focus throws and accurate witness marks. Despite claiming they're brand new lenses, they share an identical optical formula to their budget cine lenses with simply new lens coatings. Flare may be improved along with possibly sharpness and contrast, but any barrel distortion or vignetting remains the same.
Zeiss make a set of stills lenses that almost succeed in fulfilling all of my criteria. Their ZE/ZF.2 lenses - now (with the release of newer lines,) called their 'Classic' lenses. The ZE is Canon EF fit, and the ZF.2 lenses are Nikon F mount. Despite being equal, if not more costly than the Canon DSLR counterparts, they could almost be the ideal solution. But not quite. The ZE lenses do not have a manual aperture, disqualifying it from my search. The ZF.2 lenses however do, and can be remounted/adapted to fit Canon EF mount plus the aperture can be de-clicked. The only disadvantage and the reason I did not go for them however, is that the focus ring - as with all Nikon lenses - is the 'wrong way' around. Infinity should be on the right hand side of the focus scale, meaning turning the ring clockwise (from behind the camera/lens) would focus towards close-focus. This applies to both stills and cinema lenses. Whether focus pulling manually on the lens or with a follow focus, Nikon lenses reverse the direction of focus. Not only is this disorientating for the operator or focus puller, but risks fluffing a take due to focusing the wrong way.
Adapting vintage stills lenses is the other viable option. There are too many to name, but all share a number of crucial similarities - all manual, cover full frame etc. Vintage lenses are also becoming popular again nowadays, for the same reasons I was searching - the need for decent, affordable glass! The other criteria narrow down the selection significantly. Some cannot be remounted to EF due to their flange distance, such as Canon FD, the Nikons focus the wrong way, and many other brands simply aren't up to scratch optically. This leaves essentially two really decent options. Leica R and Zeiss Contax. Both are excellent choices and tick all of the boxes. There is a lot of fandom for both online, with many users revering them and swearing by them. I'm one of them, waving the flag for Zeiss Contax. I've always been a fan of Zeiss lenses, with their sharp, clean look; Zeiss Contax was what I decided on and went for in the end. The main reason for choosing Contax over the R's however is simply due to availability and price; the Leica's would no doubt perform just as well. eBay is the primary source of vintage lenses, however quality is not guaranteed and there are alternative websites to buy from, plus check your local classic camera shop - Zeiss and Leica make appearances from time to time.
I should add however, since my hunt for a set of lenses, Zeiss have released a number of new lines, many of which may be suitable for cinema use. Their Otus and Milvus lines are excellent, though are similar to the Classic lenses in that they are available in both Canon and Nikon mounts and so either do not have a manual aperture ring or focus the wrong way.
Furthermore, having bought into the Sony E mount ecosystem, whilst I can adapt easily to EF or PL mount, E mount is quickly becoming a viable solution for cinematography. Their cameras are easily capable and well equipped enough to perform in a cinematic environment, and many lens manufacturers are now producing lenses for E mount - some exclusively. I dare say that Sony E mount is a solid 3rd place behind PL and EF. If E mount is your desired flavour, Zeiss also make a number of lenses that are more than suitable. Their Loxia lenses for instance, are fully manual, cover full frame and can even be clicked or de-clicked at the turn of a screw. Sony also have a couple of lenses that have both an electronic and manual aperture, plus can be de-clicked via a switch.
If you're looking for affordable cinema lenses, there are a number of choices as detailed above. If you're not bothered with focus direction or are already used to Nikon lenses, Zeiss' ZF.2s or Milvus lenses might be serious contenders. If you're only shooting on Super 35/APC-S and don't need full frame coverage, you'll have more choice and if you're shooting Super 16/Micro Four Thirds, your options expand even more.
The above suggestions do vary somewhat in price, though all are below the cost of entry level cinema lenses such as the Zeiss CP.2s and the Canon CN-E primes. All things considered, I believe Zeiss Contax lenses to be the best option - particularly when it comes to cost. Bargains can be had on eBay and their performance is outstanding. If you're willing to put in a bit of time - patiently seeking out the desired lens(es) on eBay in good condition and at the right price, you'll have some stellar glass on your hands. Invest some more time and a little bit more cash and get a new mount from Leitax (don't get a cheap adapter from eBay) and if you wish, de-click the lens and even have a geared focus ring installed and you've got a seriously good lens suitable for cinema use at a fraction the cost of a 'proper' lens. For less than the cost of a single CP.2, you can purchase and assemble a whole set of Zeiss Contax lenses.