Reviewing LockCircle’s PrimeCircle XM50 Cine Lens
Marco Solorio of OneRiver Media reviews the PrimeCircle XM50 Cine Lens made by LockCircle. Is this lens the end-all answer to affordable high quality cinema lenses or is this another gimmick to sell hungry filmmakers into something that may not truly fit the bill?
If money were no object, all filmmakers would shoot on Leica Summilux-C primes, Zeiss Master Primes, or any other master cinematography lenses. But in the real world, the vast majority of filmmakers do not have the budget or resources to uses these types of exotic lenses. When these exotic lenses are priced as a full set, they literally costs more than an average American home (no joke). A compromise has to be made and as such, many photography lenses have filled the role when shooting with video cameras. But as many shooters know, photography lenses have many inherent issues when shooting video.
Because of this, lenses for video use is always an interesting ordeal. There are basically three categories of lens types you can use for video:
- Photographic still lenses
- Modified still lenses for video use
- True cinema/video lenses
The LockCircle PrimeCircle XM50 lens sits in the middle section, where it combines existing still photography optical technology with cinema lens performance. At the core, the XM50 is based on the German-made Carl Zeiss Planar T* 50mm f/1.4 ZF.2 fully manual photography lens with a full-frame image circle. This is a great platform to build from, as it combines performance, optical quality, build quality, manual mechanics, and cost efficiency. The base cost of the Zeiss lens is about $725 when purchased on its own from the likes of B&H Photo. I know several people that use these Zeiss ZF.2 lenses (unmodified) specifically for video use since they are fully manual with hard focus stops (more on that later). The cost of the XM50 lens is $1569, so you’re basically paying about $844 for the actual cine modification, re-housing, and hand calibration of the XM50 lens.
LockCircle adds much more to the Zeiss lens than merely slapping a focus gear around it though. Instead, the entire process is fabricated, machined, calibrated, and rehoused in a custom designed body, engineered by LockCircle. Just looking at the lens is a thing of beauty. German optical engineering combined with Italian mechanical engineering and design is a win-win proposition in my book.
The XM Body
The XM50’s all-aluminum body is made of an anodized black matte finish and is very clean. All marking are easy to read and are situated horizontally for both the camera operator (left of camera) and focus puller (right of camera). You have the option to buy the lens with either metric or imperial markings (we chose the latter since we’re in the United States, even though I know metric is a superior system, but I digress). The focus marks are hand calibrated FOR EACH LENS by LockCircle in their facility. Our XM50 was personally calibrated by Dante Cecchin, a man that is extremely passionate about these lenses, while also extremely helpful throughout the entire build process of the lens.
The red anodized aperture ring (which I LOVE) also has markings on both sides. I do wish that LockCircle had marked the aperture in T-stop ratings (following the cinema lens norm) rather than F-stop ratings, but not entirely a huge deal. In short, all visual marks on the lens body are easy to read by anyone using the lens.
The body of the lens itself feels strong and well built. Holding it in your hand feels nice. There’s a good amount of weight to the lens, but it’s not overly heavy by any means (original ZF.2 @ 350 g and modified XM50 @ 652 g). The XM50 feels about the same weight as my Canon 50mm f/1.2L (590 g) even though the XM50’s body feels stronger and more robust. The XM50 is definitely much smaller and lighter than the Canon CN-E 50mm cinema lens (1.1 kg) or the Zeiss CP.2 50mm Super Speed cinema lens (.9 kg).
Because the XM line up is based off the Zeiss ZF.2 series, there are variations in body sizes between the group. In other words, unlike a true cinema lens set that embodies the same physical size between them (in most cases), the XM lenses have varying body sizes. Having the same physical body size between your lens set can be helpful when quickly swapping lenses without having to readjust the matte box location and follow focus location. It does appear that focus gears are in the general same location (not exact) but the aperture gear appears to be the same location throughout the set. For some people, varying lens body sizes is not a huge issue, as it’s more of a luxury than a requirement.
The front element has a common outer diameter of 95mm, which is one of the common sizes for cinema lenses (114mm being the most common). The inner diameter is threaded at 90mm, so if you want to use any of your 77mm or 72mm optical filters, you’ll need a step-down ring from 90mm to 77mm. We’ve used our 77mm Singh Ray Vari-N-Duo using a LockCircle 90mm to 77mm step-down ring with perfect results; no vignetting at all (partially due to the Super35 sensor crop) on this somewhat thick filter (this particular filter includes both a variable ND filter and a circular polarizer in one unit). If you buy any of the PrimeCircle lenses, I’d suggest getting a 95mm to 77mm step-down ring like we did.
Speaking of the front element, I was caught off guard when the lens arrived from Italy to find that the front elements itself moves forward and backward when focusing the lens! I was shocked since I didn’t even think to assume there would be a chance of this prior to ordering the lens. I admit, my heart was a little broken when I discovered this when initially playing with the lens. All true cinema lenses have a stationary front element so that the lens itself stays put when integrated into the mattebox when pulling focus (including zoom lenses when zooming). However, after mounting the lens to our Blackmagic Design URSA and our ARRI MMB-1 matte box, my concern was greatly diminished since the rubber bellows unit is designed to have some amount of front element movement. Luckily this setup does not introduce any light leakage when pulling focus end to end. But if you don’t have a quality matte box and bellows element, then you’ll either have to use a fabric/rubber donut ring (which I cover extensively in my latest book, “Rigging Your Cinema Camera”) or no donut at all (which can cause unrepairable reflections when filters are used). Of course, if you’re not using a matte box at all and only use circular lens mounted filters, then the issue of the front element moving on focus is entirely moot.
The lens comes with a rear lens cap (standard plastic) and a front lens cap (aluminum). Both caps have nice, distinguishable labeling on them. The front aluminum cap has an especially nice design to it and the aluminum build is nothing short of high quality. However, the inner portion of the front cap has a felt-like lining to it, which in of itself seems to produce its own micro-sized lint particles! I’m thinking of possibly masking the sides and front of the cap and spraying this felt liner with an aerosol based glue to permanently harden and kill the felt makeup of it (or possibly carefully removing the glued on felt with a little heat since the cap is aluminum). If given the choice originally, I would have opted to not have a felt liner. It looks nice, it feels nice, but it seems to counteract the point of keeping dust out. Otherwise, the front cap truly is a nice finishing touch to the sexiness this XM lens embodies.
The XM50 has excellent focus. It simply blows the focus ability of any standard still photo lens out of the water. For starters, the lens incorporates hard stops on both ends, which is essential for true cinematography work, especially when focus pullers need to perform a point-to-point focus pull with their follow focus. Most modern still lenses (including all my Canon EF L lenses) do not incorporate hard stops, which is one of my biggest aggravations when using still lenses.
Additionally, the XM50 has a fairly long rotational focus spin at 230°, which is eons longer than any typical still lens. Another pet peeve of mine with still lenses are short focus throws, as it makes it difficult to fine tune focus, especially on moving objects. True cinema lenses typically have a standard 300° of rotational spin, but at 230° with the XM50, I have no big complaints as I’m still able to achieve highly controlled focus pulls with it. The focus ring is very smooth and easy to operate, as there’s no creeping, grinding, or loose spots. All in all, focus is smooth and perfect.
Focus breathing (the phenomenon where the image slightly zooms in and out as you focus) is minimal but not perfect (most lenses in this price range are not). This of course is inherent to how Zeiss designed the lens and has nothing to do with LockCircle’s re-engineering of the lens body. I honestly haven’t found this to be a huge issue and wouldn’t “mark off points” for this.
As with all Zeiss ZF.2 lenses, the XM50 uses a “Nikon” direction for focusing rather than the more common “Canon” direction for focusing. Generally speaking, I think many people prefer Canon rotation, but personally, I prefer the Nikon direction, as I like the “rolling carpet” method of focus pulling. Honestly I can go either way, but as a preference, I do like Nikon rotation. If you absolutely need to spin the focus in the Canon direction, you’ll need a reversing gear on your follow focus.
Lastly, the focus ring is fully geared and 360° around the lens. Standard .8/32-pitch teeth are used, so it will work with any of your existing follow focus units or remote gear heads.
My biggest complaint about modern photographic still lenses are electronic apertures. I’ve never been a huge fan of using electronic aperture lenses for video (even though I still have to use them in many cases), especially since I started with fully manual lenses in the 1980’s. Pressing buttons on any video camera to change the aperture, in steps no less, is slow, cumbersome, and in some cases, you lose some amount of accuracy between stops. In short, electronic apertures are lacking in performance for video use when it truly comes down to it.
The XM50 alleviates all of this with its fully manual aperture ring combined with a de-clicked, smooth, and accurate aperture. Because the red aperture ring is geared, you can perform aperture pulls or control it remotely with a geared head.
LockCircle doesn’t actually perform any optical modifications to the core Zeiss Planar T* ZF.2 lens itself, so you still have 9 aperture blades to work with, instead of 11 that the Zeiss CP.2 lenses incorporate. I personally prefer a high blade-count on the aperture (for a more perfect circle in mid-aperture settings) but some people prefer the non-circle look. This is a personal choice and purely subjective, so to each their own. Even with “only” 9 blades on the XM50 (pictured left), I’m totally fine with this, as it’s 1 more blade than our Canon 50mm f/1.2L EF lens (pictured right) and definitely much better than 5 or 6 blade apertures of old!
The XM50 comes in two mounts, Canon EF and Nikon F. I chose Canon EF since we do not have any Nikon cameras but do have many Canon EF mount cameras (Blackmagic URSA EF, Production Camera 4K EF, Cinema Camera EF, Canon 5D Mk III, 5D Mk II, 7D, and several other older DSLRs). Keep in mind, if you own (or intend to own) Nikon bodies, then definitely get the Nikon F mount, since that can be used on both Nikon AND Canon mount bodies (with an inexpensive adapter for Canon), but not the other way around.
The mount itself is standard and well built. There are no communication pins since the lens is fully manual, so it’s as straight forward as it can get.
Off the bat, I could tell the XM50 (or more accurately in this comparison, the Zeiss ZF.2 lens) was slightly softer wide open as compared to my Canon 50mm f/1.2L EF lens. Not surprising since the Canon lens is about twice the cost of the Zeiss lens and known for its optical performance. My initial findings were confirmed once I shot both lenses on our test charts. Wide open, the XM50 is definitely usable, but you’ll want to stop down to around f/2 to start getting a truly sharp image. At f/2.8, the XM50 actually seems to perform better than the Canon 50mm L with what appears to be slightly better contrast and sharpness in the corners with lower chromatic aberration. Remember that the XM50/Zeiss optics (in original form) are roughly half the cost of the Canon 50mm L counterpart.
I found the overall image of the XM50 slightly warmer than our Canon, but only by a mere hint. Some people prefer this as it can work well with skin tones. I’m fine with either, but again, the comparison between the two is almost imperceivable. Personally speaking, the comparison is moot and quite frankly, a purely subjective preference.
Bokeh quality fairs well and is somewhat similar to the Canon (which uses 8 aperture blades), but as mentioned, the XM50 incorporates 9 blades to ensure a circular bokeh look. The bokeh circles are smooth and solid… no “hooping” with these optics!
Other than what I’ve already shown, I’m not going to cover additional in-depth optical assessments on the XM50 since the Zeiss Planar T* 50mm f/1.4 ZF.2 lens (to which the XM50 is built on) has been tested and reviewed countless times on the internet. One good source to find technical optical performance of this lens while also compared to the Canon 50mm f/1.2L lens is on DxO Mark.
The closest comparison to this lens (in cine form) is the ZF.2 Cine-Mod prime by Duclos. Built on the same exact Zeiss ZF.2 lens, the Duclos option costs a little less, but in my opinion, the LockCircle PrimeCircle XM50 lens has a far superior body design and is closer to cine form. Don’t get me wrong, Duclos makes incredible lens modifications from a wide range of lenses they offer and their optics knowledge is bar none. But for me, the LockCircle XM50 wins it for us, compared to the Duclos ZF.2 Cine-Mod.
The Rokinon 50mm T1.5 cine lens could also be compared to the LockCircle XM50 and costs considerably less. But in my opinion, there’s really no comparison. We have a rather extensive Rokinon collection already (with the Rokinon 35mm Cine lens vs. the Canon 35mm f/1.4L photo lens reviewed by me back in 2012), but Rokinon’s extremely plasticky build quality always makes me extremely hesitant to use them in heavy production use. Likewise, they’re typically quite soft fully wide open (and seems to vary in terms of wide-open quality with regards to when/how they’re manufactured). Some people have sharper wide-open Rokinons (of the same model) than others, which makes me assume manufacturing tolerances on the Rokinon lenses could be a bit better, but like anything, there are always some compromises to such low cost options (which isn’t always a bad thing). But again, I’d much rather use the Prime Circle XM50 over the Rokinon 50mm T1.5 in a professional environment without a second thought.
XM50 + URSA
One of the biggest reasons I purchased the XM50 lens was to use it with our Blackmagic Design URSA EF camera. Although electronic aperture lenses work fine with the URSA, I personally wanted a new 50mm lens to match up with the URSA that was more cinema style centric. The XM50 really fits the bill well. So much so, the lens looks like it was intentionally designed for the URSA. Coincidences aside, using the URSA with a fully manual lens in a complete aluminum housing with geared barrels and de-clicked aperture is a very well made match.
I will say that the focus barrel is fairly close to the lens mount, so fitting in a follow focus unit in there with a matte box up front can be a tight proposition, but not an impossible task. The teeth of my Tilta FF-T03 follow focus only mesh partially with the lens’ focus gear, but enough to where there is no slippage and gets the job done. And again, using a rubber bellows, as in the case with my ARRI MMB-1 matte box, will allow the front element to move while keeping a tight seal to avoid any un-repareable light leakage reflections. All in all, I enjoy using the XM50 lens with the URSA.
In the end, I’m very happy with the XM50 lens. The price is very competitive and fits well into the budget of most filmmakers. I have no regrets buying the lens, despite my initial shock of the moving front element. Although the wide aperture optical performance (f/2.0 to f/1.2) isn’t as good as our Canon 50mm f/1.2L EF lens (which again, costs about twice as much at the core level), the XM50’s optical quality is still very good. And although more costly than Rokinon cine style lenses (of which we have a large collection of as mentioned), I would greatly prefer the LockCircle XM lenses over the Rokinons in a heart beat. In essence, the LockCircle XM lenses are a superb solution when you want cine style lenses with really good optical quality, but with vastly superior performance to the Rokinon lenses and without breaking the bank investing in alternative Canon CN-E or Zeiss CP.2 super speed cinema lenses. The LockCircle XM cine lenses fit right in the middle, both cost-wise and performance-wise. For us, the XM50 is our new workhorse 50mm lens for video work, replacing our Canon 50mm f/1.2L EF lens. If we specifically need higher optical quality for a particular project, we’ll continue to use our extensive Canon L line up, or better, the Canon CN-E cinema prime lenses. But for the vast majority of productions where we need to slap on a 50mm lens, the XM50 fits the bill perfectly. In short, we’re very happy with the choice in purchasing this lens and do recommend it.
Extremely high build quality with quality components
Size to weight ratio is excellent
Fully manual controls
Easy to read markings on both sides of the body
Long 230° focus rotation with 360° focus gear and smooth movement
Focus is lock-to-lock on both ends
De-clicked and 360° geared anodized red aperture ring
Common 95mm front element for matte box insertion
Fast aperture at f/1.4 for low-light shooting and narrow DOF
Full-frame image circle can be used on full-frame cameras
Affordable: The XM50 50mm lens is the lowest cost lens from the entire XM series of lenses
Sexy Italian design with quality German optics
Moving front element
Felt on inner lens cap produces micro lint
230° focus rotation rather than common 300° rotation, but way longer than still lenses
F-stop ratings rather than T-stop ratings
Focus spins in “Nikon” direction
XM series have dissimilar body sizes between the group
No PL mount option
Some XM series lenses drastically jump in price, which is a reflection of the original Zeiss collection itself and how Zeiss prices their lenses.
PrimeCircle XM50 Specs
Focal Length: 50mm
Aperture Range: f/1.4 to f/16
Focusing Range: .45m to infinity
Coverage at Close Range: 180x120mm
Angular Field: d. 45°, h. 38°, v. 26°
Dimensions: Ø 97mm, length 132mm
Sensor Coverage: Full-frame 24mm x 36mm
Front Outer Mount: 95mm
Front filter thread: M90 x 1.0
Focus Gear: .8 / 32-pitch @ 360°
Aperture Gear: .8 / 32-pitch @ 360°
Camera Mounts: Canon EF, Nikon F
XM 50 Product
Cost: $1,569.00 USD, €1,399.00 + VAT (shipping and international currency exchange fees not included)
All photographs by Marco Solorio of OneRiver Media. © 2015, OneRiver Media, all rights reserved.