If you plan to take your filmmaking and video production to the next level, investing in cinema lenses could be a good strategic move. They are, after all, specifically designed to meet the needs of professional filmmaking and high-end commercial video production workflows. Read on to find out how.
Geared rings and aperture measured in T-stops instead of f-stops are just some of the most visible differences between a cinema lens and an ordinary lens.
1. More consistent exposure: T-stops instead of f-stops
One of the biggest differences between cinema lenses and ordinary lenses is apparent in the lens names:
While ordinary lenses use f-stops, cinema lenses use T-stops.
- T-stops indicate measured transmission efficiency: they tell us how much light reaches the image sensor.
- F-stops are a calculated number. This number is obtained by dividing a lens’ focal length by the physical diameter of its aperture diaphragm (entrance pupil).
T-stops account for the loss of light inside the lens, while f-stops don’t.
There will always be some light lost as it passes through the elements inside the lens, but just how much depends on the optical design. An f/1.4 setting on two different lenses doesn’t necessarily result in the same brightness even at the same ISO speed and shutter speed settings. This can cause jarring inconsistencies if you change lenses or use multiple cameras to shoot the same scene, and correcting them by "matching" the footage is a tedious process!
T-stops, on the other hand, are more consistent. “T1.5” will result in the same amount of light reaching the sensor regardless of the lens you use, so the brightness will stay the same at the same settings. There’s less exposure matching to do onsite and/or in post-production, which adds up to substantial time and cost savings.
Know this: Colours are matched, too
Canon has taken great care to ensure colour consistency and aesthetics within every set of cinema lenses, so when you swap out a lens for another one, the only visual aesthetic that changes is the focal length. That means even less to match in post-production—good news for your budget and post-production crew.
2. Quick, easy lens swaps with minimal rig adjustments
One of the first things you’ll notice when you look at a set of cinema lenses is that all the lenses in the set are consistently sized, or “matched”. Look at the images above, which show Canon’s RF mount cinema prime lenses (CN-R lenses) and observe the following:
- Consistent size: even when the sizes vary, the difference is small.
- Consistent front diameters (114mm on CN-R lenses) and consistent filter diameters.
- Consistent gear and marking positions.
The weights of the lenses are consistent too. Again, using CN-R lenses as an example:
| Lens | Weight |
| CN-R14mm T3.1 L F | Approx 1.3kg |
| CN-R20mm T1.5 L F | Approx 1.4kg |
| CN-R24mm T1.5 L F | Approx 1.3kg |
| CN-R35mm T1.5 L F | Approx 1.3kg |
| CN-R50mm T1.3 L F | Approx 1.2kg |
| CN-R85mm T1.3 L F | Approx 1.5kg |
| CN-R135mm T2.2 L F | Approx 1.5kg |
These are deliberate design decisions that will make lens switching quicker and easier on set:
- The aperture and focus rings are at the same position on every lens, so you don’t have to reposition your follow focus system or other controlling gears.
- You don’t have to rebalance your gimbal or support system by much because of the consistent lens sizes and weights.
- You can use the same matte box for all lenses in the same set because of the consistent front diameter.
That adds up to a lot less readjusting and matching with every lens change. Think of all the time saved!
Watch: Seamless lens swapping
As cinema lenses that belong to the same set have consistently positioned markings and gears, lenses can be swapped in seconds.
3. Operability that caters to the needs of professional productions
Cinema lenses are designed to better suit professional filmmaking and video production situations, which have some different requirements from still shooting.
i) Designed for precise manual focus control
While autofocus systems have come a long way, precise manual control over focusing is still crucial for achieving professional-quality footage and storytelling in many different types of production. In fact, manual focus pulling is often preferred in high-budget productions and professional filmmaking environments because it offers a higher level of creative control over the speed and consistency of focus transitions.
To control the focus, you will need a follow focus system. Whether you are shooting alone or have an assistant to help you pull focus (a focus puller/1st Assistant Camera), a follow focus system (including focus control motors) makes it easier to adjust the focus while the camera is on a tripod or rig. The gears on the focus ring of a cinema lens are designed to be attached to such a system.
You will also notice the detailed focus markings on the lens, which is useful for pulling focus from one precise part of the scene to another repeatedly. After all, although nailing a scene in one take is ideal, it often doesn’t happen in reality!
The focus throw (the degree of rotation required from infinity to the closest focusing distance) is also longer than normal lenses—300 degrees on CN-R and Sumire prime lenses. This allows for smaller, more precise focus adjustments, which is important especially when working with a very shallow depth of field, where the slightest adjustment makes a significant difference to what’s in focus and what is blurred. It also enables smoother, more natural focus transitions, improving the viewing experience.
Watch: A follow focus unit in action
ii) Clickless aperture (iris) ring
In still photography, aperture ring clicks are a useful tactile indication of how much the aperture setting has been adjusted. It’s why they are present on the aperture rings on the non-cinema lenses that have them.
On the other hand, video requires smoother, soundless adjustments. You’ll be adjusting the aperture a lot, whether to control or change the depth of field as part of visual storytelling, or to maintain proper exposure under changing lighting conditions. You don’t want sudden jumps in exposure during the adjustment, nor do you want the clicking from the aperture ring to be recorded on the audio track!
Thus, by default, cinema lenses have a mechanically controlled aperture ring, also called an iris ring, that gives you direct control over aperture settings. This ring is smooth and clickless to ensure silent, seamless transitions.
Watch: The clickless aperture ring on a Cinema EOS lens
No clicking at every aperture stop: Cinema lenses are clickless out of the box.
iii) Marked for teamwork
The depth of field, distance, and T-stop markings on cinema lenses are on both sides of the lens barrel, which makes them visible from the “smart” left side of the camera (when looking in the same direction as the lens), the “dumb” right side, and from behind. This allows both you as the camera operator and your 1st AC/focus puller to see, access, and communicate about these settings regardless of which side of the camera you are on—no one has to move over and potentially get in the way!
Markings on the left side…
…and the right side
There will be times when you need to operate the camera from a different position or angle to achieve your desired shot. Having the important markings on both sides lets you see the essential information regardless of where you are relative to the setup, allowing better versatility.
Know this: Phosphorescent indicators
See those markings glowing in the dark? The indicator markings on the front barrel feature phosphorescent paint, improving visibility when you are shooting at night or in dark areas.
4. Designed to minimise focus breathing
Changes to the focus position inevitably cause the angle of view to change slightly in a phenomenon called “focus breathing”. Given how frequently focus position changes occur, throughout most productions, focus breathing can be quite jarring!
While there are different methods to correct focus breathing, nothing beats reducing it from the source: the movement of focusing elements inside the lens. The optical design of cinema lenses reduces such movements so focus breathing is under control from the very start. This keeps both the framing and the angle of view of your shots consistent: just the way you intended.
Also see:
Videography FAQ: What is Focus Breathing Correction?
Conclusion: A necessity for elevating your filmmaking
Cinema lenses help smoothen the filmmaking workflow both on the set and in post-production, leaving valuable time and energy for other things. In fact, they are essential for high-end productions because the consistency that they deliver results in substantial time and cost savings. Cinema lenses also offer a degree of creative control that’s unique to them, so it becomes easier to create footage that looks the way you want it to, right down to the subtle transitions. In that sense, they are a must for any experienced filmmaker or video producer who wants to take their skills and business to the next level.
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