Everything you need to know about making the leap to purpose-built cinema optics.
Although lenses designed for stills cameras often have speedy autofocus and image stabilisation, there is nothing quite like using a lens built purely for the unique needs of filmmaking. Cine lenses are specifically for moving-image work, which can involve a completely different workflow and shooting style, often including dedicated crews and operators. And the tactile user-experience of delivering optical performance while racking focus or zooming – and consistent light transmission due to T-stop markings – makes them the perfect equipment to lift your work to a higher level.
Starting with the physical attributes of cinema lenses, the best ones are designed for a consistent size, which helps with accessory use. Lenses matched in size make lens swapping easier when using support and motion control equipment, and consistent gear ring placement means less time moving motors around. It also means that balancing your rig or stabiliser is much faster.
With filters, stills lenses use threaded ones that screw directly to the front. But there is very little consistency across lenses, so you either have to buy multiples in different sizes, or use an accessory such as the Revoring – a variable step-up ring. While some cinema lenses do feature threads for screw-on filters, the most common way of adding filtration is with a matte box. Attaching one can be done with either a rod support, or by using a clamp-on system around the front of your lens. With standard front diameters ranging from 80mm all the way up to 162mm, you must make sure the clamp system matches with the front diameter of your lens.
Most sets of cine lenses will have a consistent front diameter, like the Canon CN-E and Sumire primes with a 114mm front. So, a matte box with the right-size clamp can easily be used when switching between focal lengths.
Many high-end cine lenses come in the Arri PL Positive Lock mount – a very secure system with a locking design. This greatly reduces any play in the mount, that could translate to image shift while focusing or zooming.
Where a stills lens would typically be turned to click into its mount, a PL lens is attached by lining up the locating pin in the mount with a corresponding notch on the lens, then the mount itself is turned to securely lock the connection. With full metal bodies and larger lens elements, these heavier cine lenses have a need for greater mount stability and can benefit from the use of a lens support rod system.
Light controlled to a T!
Stills lenses use f/stops – a mathematical value calculated to represent the light hitting your sensor. Cine lenses use T stops, an actual measure of transmitted light being received by the sensor through the lens. This standard aims to keep consistent exposure across different lenses at the same T-stop values, helping to match exposure when using multiple cameras. You could also switch to a different focal length of the same T stop and exposure shouldn’t change. This is more accurate for lenses within the same set, as each manufacturer rates T-stop values slightly differently.
With most stills lenses, aperture is controlled via the camera, with electronic adjustments in discreet steps. These can be noticeable both visually and audibly when recording. The manual control of a cine lens allows for continuous iris adjustments without any hard steps, meaning exposure changes are smooth while recording. And, with a long rotation of the aperture ring, you have more precision. A manual aperture can also be managed wirelessly by a motor and lens control system.
Focus by feel
One of the biggest differences between stills and cine lenses is with focusing, both in terms of the mechanics and the feel. Stills lenses are often electronically driven with quick autofocus. The manual, mechanical focus of a cine lens is designed for precise, human operation. There are a few hybrid cinema lenses that feature electronic capabilities – such as Canon’s Cine Servo lenses which allow zoom, focus and iris to be controlled electronically – with some even having autofocus.
The vast majority of cine lenses have a much longer focus throw for smoother, more precise adjustments. And the focus ring on cine lenses tends to have a hard stop at either end of the range, while most stills lenses will continue to rotate beyond close focus or infinity. While cine lenses can be used manually and by solo operators, they are designed more for crew operation and perform well with focus motors, wireless controls, rangefinders and other focusing tools. If you work with a minimal crew, then a low-cost wireless focus solution like the Tilta Nucleus-M is ideal.
Cine lenses are built to eliminate breathing, which is a slight focal length change when moving through the focus range. In stills it is not noticed when capturing a single frame, but with moving image it can be distracting. Similarly, another optical trait is that cine zooms are designed to be parfocal, so they maintain focus while being zoomed.
Image quality differences between stills and cine lenses can usually be quite obvious. However, there are a lot of optical similarities between Canon’s CN-E Primes and L-Series AF primes. But they are very different in mechanics.
A big consideration, however, is the level of quality control when it comes to both the optical elements and the overall look of lenses across an entire set. Cine lenses are often bought as a partial or complete set, unlike stills glass.
Factors like this contribute to giving cinema lenses a higher price tag. Tighter tolerances, higher quality materials, longer design and production times, as well as being part of a smaller market are all reasons why cine lenses are typically valued much higher to a stills equivalent. But invest in quality, and your work should reap the dividends.
Let CVP take care of your equipment
Many cinema lenses feature an interchangeable mount, allowing you to swap mounts from PL to EF, for example. Some of Canon’s cine lenses can have their mounts changed by an approved service centre. Although some systems allow filmmakers to do their own mount changes, it can be challenging – and you may lack the correct tools. It’s best to leave it to the technical experts, like CVP, to get it right.
It’s also far more important to have cinema lenses properly calibrated, than with stills lenses. Not having your lens calibrated correctly could result in issues such as focus scales being out, or zooms not being parfocal. CVP’s in-house ProRepairs team has a specialised lens department to service your lenses, making sure they are within manufacturer specification and fully accurate.