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Xeen video-cinema lenses were introduced in 2015
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Rokinon 35mm T1.5 full-frame, wide-angle lens
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Canon Cinema prime CN-E35mm T1.5 L F (EF mount) lens
The use of DSLRs and cinema-style cameras such as the Canon C100, or the older Panasonic AG-AF100, has opened up a whole new world of shooting with a more cinematic feel. Because these cameras use standard photographic lenses, it made getting into one of these cameras (a C100 for me) very cost effective, as I already owned a collection of Canon EF lenses for my DSLR.
Not long after obtaining my C100, I ran across the term “cinema lens” (or “cine lens” for short), and wondered what the point was. Why are there a set of lenses specifically for shooting video? I didn't pursue my curiosity very far, as when I looked at Canon's offerings, the price tag made it a purely academic exercise—there was no way I could justify the cost per prime lens.
Perhaps a year ago I was interviewing a church for an article and the video director talked about using a Rokinon cine lens kit for their video production work. I found this was a product line far closer to my budget, and explored the concept further. In this article, we're going to talk to both Canon and Rokinon about cine lenses, and take a closer look at the Rokinon DS cine lens kit that I purchased to support a higher-end project for which I've recently completed the principle photography.
What's a Cinema Lens?
“Still lenses have been honed over the decades to be optimized for still images,” states Larry Thorpe, national marketing executive at Canon USA. “The cinema lens has been tuned to deal with moving images, and more importantly, the dynamic intervention of the camera operator in the creation of those images.”
With still photography, when you actually capture the image, the lens settings are fixed. You don't change the iris or focus in the middle of the shutter release.
However, in video capture, it's common to change the lens settings in the middle of a shot. “For example, in scenes with numerous talent, the director of photography will be working the lens throughout the shot, rack focusing, etc…. This is a craft honed over the decades,” Thorpe adds. “With that comes a totally different design of the lens.”
And it's not just the focus that changes during a shot. As you follow an actor from one lighting environment to another, you may need to smoothly adjust the iris to let in more or less light during the course of the shot. Additionally, if it is a cine zoom lens, one of the central design criteria is that it be parfocal—that is, it will maintain sharp focus as the zoom control is exercised throughout a given shot.
“Typically for true cine use, you want total manual operation of everything, adds Rich Rothbard, marketing manager for Elite Brands (parent company of Rokinon). “You don't want the camera to autofocus. Manual focus is desirable to ensure you get the result you want at the time you want it.”
“The first thing,” Rothbard continues, “and one of the major things, is cine lenses have gearing on both the aperture and focusing rings, so they can mate with follow-focus devices.”
A photo lens doesn't have this, and therefore does not work as well with follow-focus systems.
A follow-focus is a device that mounts next to the lens via a rail system and allows easier and more precise access to the focus and/or aperture rings on the lens. It can consist of a whip-style connection that brings a control knob to the back of the camera; or a dial with adjustable hard stops that is operated from the side of the camera.
The stops assist in getting accurate rack-focus moves during a shot.
The iris operation is also modified from how most photography lenses operate.
“The aperture ring in a cine lens is de-clicked,” explains Rothbard. “When you move the ring, you aren't limited to specific f-stop settings as you are with most photographic lenses. It changes smoothly, just like the focus ring, and is infinitely variable between its smallest and largest opening. The detents on a photography lens will make the aperture change jerkily, as well as making noise—something you want to avoid on a video shoot.”
Another difference in the focus and aperture rings is that they have hard stops. With most photographic lenses, when you reach the limit on focus, you can keep turning the ring and it just doesn't have any effect. Not so with cine lenses, which makes rack-focus moves reliably reproducible.
t-stops vs f-stops
Another change in cinema lenses is that they are calibrated in t-stops instead of f-stops. An f-stop is a ratio of focal length to aperture diameter, used as an indication of how much light will be passed through the lens. However, it doesn't take into consideration the light that is absorbed or reflected back from the glass elements in the lens.
Therefore, you can attach two different f-stop calibrated lenses to a camera, set to the same f-stop, and get different exposure levels.
t-stops are similar to f-stops but take into consideration light loss as the light passes through the lens. Therefore, for a given lens line, different lenses set to the same t-stop should result in the same exposure level.
Other Differences
As adjusting focus and iris during a shot is a common event, the rings on cinema lenses typically have a much longer “throw” distance (i.e. rotation angle)—you turn the lens a lot further to change focus, which gives you greater accuracy. Additionally, the lenses are marked and calibrated to a finer degree of accuracy as well.
In cinema, it's common to have a “focus puller”—a camera assistant who stands to the side of the camera and adjusts the focus or exposure as needed throughout a shot. This person needs to be able to see the settings on the lens. Therefore, unlike photographic lenses where it makes sense for the scales to be on the top for easy visibility by the photographer, cinema lenses markings are on the side of the lens for easy visibility by an assistant. Often the marks are present on both sides of the lens, so that the focus puller can stand to either side of the camera.
Additionally, as cinema work usually deals in prime (fixed focal-length) lenses, it's important that the iris and focus rings are in the same physical location on the lens barrel to line up with a follow-focus device, making lens change-outs quicker.
Are All Cinema Lenses Equal?
Not unlike photography lenses, there's a wide range between the lowest cost cinema lens and the highest cost lens. We researched prices for 24mm prime cine lenses and found you can get a Samyang T1.5 VDSLRII for $699, Rokinon T1.5 DS for $799; a Rokinon Xeen for $2,195, and a Canon CN-E T1.5 L F for $5,220. That's a factor of 7.5 between the lowest price lens and the highest price lens. So, what is the difference?
“With the high-end cinema lenses,” states Thorpe, “the expectation is the highest optical quality, because the material is going to end up on large theater screens. Any small aberration in the lens will be perceived at that size. In the digital arena, with 4K, 5K, and 8K resolutions, that imposes an even greater pressure on the image quality as well.”
There's an entire science around the glass in cinema lenses. “How does the lens manage strong highlights?” states Thorpe. “Car headlights, for example. They create all kinds of reflections in the lens bouncing off the interior of the lens barrel. There are specialized paints and internal mechanical design strategies as well as lens coatings to minimize reflections that would otherwise contaminate your blacks.”
Another characteristic is the bokeh, or blur of the background, that is expected in cinema-quality productions. “The iris, and how it affects the bokeh—especially the highlights that are defocused in the background—is important. Highlights should be circular, and you only get that when you have a large number of blades in the iris. Canon cine lenses have a large number of blades to get this effect.”
Cinema work is done in all kinds of environmental conditions, and the lenses need to be able to stand up to this. “The physical mounting of elements inside the lens is critical to achieving the necessary optical performance,” states Thorpe. “There's an advanced science entailing special materials and mechanical designs in mounting the individual lens element's components so that [they sustain precise alignment of the total optical system at different temperatures.] The opto-mechanical design has to be extraordinarily accurate. All these things can add significantly to the cost of the lens.”
Rokinon's Xeen line of lenses are intended to compete with the Canon line of cinema lenses. If your desire is to create the best high-end cinematic result possible, higher-end lenses are the way to go. If you're looking to simply up your game with your cinematic look, the lower-end cinema lenses can add a lot more control and a better look to your production when compared to still camera lenses.
“Lenses are one of the products where you get what you pay for,” summarizes Thorpe. “When you see lens prices dropping dramatically, there has to be cost cutting. Different glass quality, lower-quality options for materials, and lower quality coatings are common ways to reduce a lens' price.”
Hands-on with Rokinon
This year, my video production company has had the pleasure of being engaged for several higher-end, and thus higher investment, productions. One of the areas I chose to improve upon is my lens inventory. I had been using Canon L series zoom photography lenses (or equivalents) for my work to date, and while that was fine, I wanted better control over focus and iris for these new projects. After some research, I invested in a series of Rokinon Cine DS prime lenses: a 10mm, 16mm, 24mm, 35mm, 50mm, and 85mm. We recently completed eight days of principle photography on one project where I moved into the director role, and we brought on Mark Hanna (another CPM frequent contributor) as the cameraman for the project.
Actually, I bought the 10mm first by itself. I had been increasingly unhappy with the soft images my Canon EF-S wide-angle zoom would produce, and wanted to try something that would give me better results on the wide-angle side of things. I was thrilled with the results – way better than the EF-S zoom at its widest setting.
Using the Rokinon lenses on the project was a wonderful experience, and I have no regrets. The lenses produce crisp images; there was one shot of a glass beaker in a laboratory that we shot with the 85mm lens, and we both exclaimed when we brought the image into focus—it looked stunning.
We used the lenses with a Came-TV FF-01 follow focus, and found that the combination of the Rokinon Cine DS lenses and the follow focus gave us fantastic rack-focus shots, as well as being able to pull focus cleanly.
It took a little getting used to, having to change out the lenses ever time I wanted a different focal length. You need to plan more time for your shoots to allow for this, so for “run and gun” material I'd still use my photographic zoom lenses.
I did find that the Rokinon Cine DS lenses were very consistent with exposure – as a test, changed out each lens for the exact same scene and set the exposure based on the waveform monitor built into my C100. This yielded the same t-stop for each lens. Therefore, noting the t-stop used on one shot and setting another lens to the same t-stop for the same scene should give you an almost perfect exposure match.
My only complaint is that the Rokinon lens hoods feel a bit flimsy, and took a little more care to get them attached properly due to the amount of flex in them. However, I didn't have any actual problems because of this.
On the 16mm lens, unless you're pretty close to the subject, “infinity” was pretty much the focus point needed, which seemed odd. But it's a wide-angle lens, and those seem to be that way.
I'm in post-production on this project now, and have been very impressed with the results we obtained. The footage looks great, and the solid control over iris with the geared rings was awesome.
