The majority of the readers of this article who shoot video probably use still lenses. You might ask yourself why you may need different lenses for video while your existing photography ones work just fine. In this article I'd like to show you certain features of the cinema glass that you probably always wanted subconsciously. Maybe after reading this you'll start saving up the money for one.
The Definition of "Affordable" In Video
If you haven't invested much in video, it's way more expensive than still photography. When I say "affordable" in terms of video gear, it is affordable only in the world of video. From a photographer's standpoint, this may sound crazy expensive. There are lots of cinema lenses on the market ranging from four-figure price tags to six-figure ones. The most common cinema lenses of high quality costs five-figure amounts in US dollars. That's why glass that's below the $5,000 range is deemed "affordable."
In this article I will speak about cinema lenses in general and although I'll give examples with lenses that cost a fortune, there are affordable models that can do a great job too. Don't get discouraged by pricing, but focus on their features, so next time you work on a higher budget project, you know the advantages and disadvantages of cinema and photography glass.
Distinctive Features of Cinema Glass
The lens is one of the tools for making a moving picture. It allows changing focus, zooming, and combining it with different accessories that aid the shooting workflow. When I started working with video, I never thought there was more than just optical quality of the cinema glass. Here are some features you have to be aware of.
Look at the image above. Don't you think cinema lenses look way more professional than the professional still ones? Definitely. If you want to look more professional, you may get cinema glass just for looks' sake.
Lens Size and Weight
If you've noticed, most cinema lenses are way bigger on the front than their stills cousins. The 28mm Carl Zeiss Compact Prime on the picture is much larger than a 28mm stills lens. Just as with the "affordability" term, this lens on the right is a compact cinema lens.
You can find whole series of cinema lenses that are exactly the same as the outer diameter and the same size, such as this Leica cinema set:
The reason for having lenses of the same diameter is the accessories that may be used with them. Imagine using ND filters for a certain scene. By switching lenses you don't have to switch to different filter sizes. You are going to put the same filter and thus not only saving money on filters (OK, for a $140,000 set, the expression "saving money on a filter" is inappropriate), but you are sure the image will be exactly the same, because you use exactly the same filter.
When using matte boxes you don't have to worry if the lens' front diameter will fit it. You just change the lens and it fits with everything else seamlessly. The same for follow focus units, remote zoom, and aperture control units. Having the same lens diameter doesn't require changing the configuration of the units or switching matte boxes.
Being of the same weight means you can change different focal length primes of a given set and you don't have to re-balance any stabilization system. If you've worked with one, you know what it means.
Larger rings allow to fit more lens marks such as focus distances or aperture values.
One of the most used features of a lens in video is changing focus. For still lenses your focus is most probably electronically controlled from your camera's autofocus capability. Let's say you have a scene where you need to rack focus from one fixed object to another. As objects don't move you can set the focus ring at the position where the fist object is in focus. Then you rotate the focus ring until the second one is in focus and mark that position. How do you mark it on a still lens?
You can't. See how moving the focus from 3 to 5 meters (on this lens on the image) requires working with a clockmaker's precision when rotating the ring. Also the ring doesn't have a hard stop. When you reach to the infinity mark and you can continue rotating the ring... to infinity. Although using follow focus units with photography lenses allows for more precise control you still have a very little room for movement.
On the other hand with cinema lenses the focus ring has hard stops at the beginning and at the end. Also its movement is more comfortable from its minimum to its maximum distance mark. You can be more precise even without a follow focus as marks are clearly visible and distributed on a larger scale.
Talking about focus, there is a defect in the lens optics called "breathing." This is when racking focus the image looks as if it's scaled up or down. Still lenses do that all the time because they are not intended for video use. Cinema lenses, however, have that breathing minimized or completely eliminated. You can see the effect of breathing of a still lens in the beginning of the following video:
The aperture, or the iris, is controlled by a ring on the cinema lenses. The ring moves smoothly from value to value without any clicks or the need of electronic controls such as on the modern still lenses. The cinema lenses are marked with T-stops instead of f-stops. T-stops is a more precise value. I discussed that in a previous article.
Cinema zoom lenses are generally quite expensive. When zooming in or out they don't change their physical size. This is a very important property especially when the camera rig is balanced on a stabilizer systems. If zooming affects the balance even a slight focal distance change would require rebalancing. High-end still lenses also don't change in size. However if you need to zoom them while recording they don't have a smooth zoom transition. Most of the time it looks jumpy. It's not a problem for still photography but it is for video. On cinema lenses the zoom is smooth all the way.
Most of us who are used to zoom lenses in still photography know that when you zoom in you may have to re-focus. Lenses that keep the focus regardless of the zoom level are called parfocal lenses. This is very important for video. There are parfocal still lenses too, although this is something you may have never noticed or used because you have autofocus kicking in on every half-press of the shutter.
Good stills glass will have good optical quality for video. It's hard to recognize cinema from stills glass quality just by recording a video of your cat in your living room. But if you put the lens in difficult lighting situations such as direct bright light or high contrast scenes, you will see the picture is different.
Color, Contrast, and Sharpness
Although lenses of different manufacturers may vary as color and contrast interpretations, most of the time the cinema lenses of one brand will have consistent color and contrast features throughout a production set. Sharpness in the corners is a must.
This is the optical defect where lines of high contrast in the image are accompanied by rainbow colors that originally weren't there. The cinema industry is highly intolerant to such imperfections. That's why production of lenses for video minimizes or completely eliminates such issues.
Cinema glass should not vignette whatsoever. Although that's easy to fix in post, it is not present in the cinema glass or is almost impossible to be detected.
Pictures shot with wide-angle or long focal length lenses in photography may have barrel distortion. We can fix that in post sacrificing resolution. In video, distortion is highly noticeable. That's the reason why cinema lenses minimize distortion, although it's sometimes present even in high end ones. Big distortion on a 24mm lens is something probably negligible for the stills photographer's eye.
Bokeh and Light Flares
This is all subjective, but cinema lenses have a beautiful bokeh and produce great light flare effects. Shooting with lights aiming towards the camera can introduce really beautiful results, especially if you combine them with a shallow depth of field.
Pseudo-Cinema Versus Real Cinema Lenses
You are still wondering why there's cinema glass that costs $4,000 and one that costs $40,000. Although lots of the sub $5,000 lenses are of great optical quality, most of them are based on still glass optical technology in terms of glass properties, coatings, and so on. They are also called pseudo-cinema lenses. On the outside they have the properties of a cinema lens required by the very industry. These properties include the physical aperture control, smooth zoom, hard stopped focus rings, minimized breathing, etc. For our eyes, we will find most of these affordable lenses great for our needs. I have watched comparisons such as this below and I was pleased to find that a sub $5,000 lens investment can be a very smart one:
In most cases, if you don't rack focus and do not zoom, still lenses may look great in most situations. But once you see the image of a cinema glass in difficult light situations, even a pseudo-cinema lens, you will know why it costs more. I'm glad there are pseudo-cinema lenses. They are the bridge to higher end visual quality for those of us who are working on sub-million-dollar projects.