Cinema Lenses Vs. Photography Lenses

INTRODUCTION

There’s a world of difference between the price of cinema lenses and those designed for still photography. So, why is it that almost all industry film shoots for series, movies or commercials use these bank breaking pieces of glass over more cost effective consumer options?

Lets go over the practical and aesthetic advantages and disadvantages of cinema versus photography lenses, to determine which is the better choice in which situation.

ERGONOMICS

The biggest immediate difference between photo and cinema lenses are their construction and ergonomics.

On average, cinema lenses are larger, heavier and are specially designed to be compatible with professional cinema camera accessories. For example, they have a sturdy, rounded front lip which clip-on matteboxes can be clamped directly onto.

They also have focus, aperture, and sometimes zoom rings, with geared teeth on the outside of the barrel which can be used to manually adjust these settings. 

Cine lenses often come in a consistent size and length across prime lens sets, as well as with a consistent front diameter - which makes it easy to do things like balance it on a gimbal or quickly put on a mattebox with the same sized back when changing lenses. 

Modern photo lenses are often designed to change aperture electronically by flicking through a switch on the camera body (although some do come with an additional manual iris ring). They can screw circular filters onto the front thread of the lens rather than using clip-on matteboxes.

FOCUS

Although these technical differences may seem small, the biggest practical effect they have is that photography lenses and cinema lenses are designed to be used in different ways by different sized crews.  

Photo lenses are more geared towards solo operators, whereas cinema lenses are manufactured for use with a full camera team consisting of a camera operator, a 1st AC and a camera assistant.

This is because of the different ways that these lenses are designed to focus. 

Photography lenses can autofocus when used with compatible cameras - such as mirrorless bodies or certain models geared towards broadcast or entry level cinema use, like the Sony FX series. 

They use internal motors to automatically move lens elements, or pieces of glass, until the image is sharp.

Modern mirrorless cameras combine phase detection autofocus and contrast detection systems. Phase detection compares two images - one from the left side and one from the right side of the lens - to determine whether the subject is in front of or behind the focus plane. The motor will then move the elements until the two images align perfectly and the subject is in focus.

While contrast detection analyses the image from  the main sensor until it finds the point where contrast (or edge sharpness) is highest - which means the subject is in focus.

Practically these systems are now very accurate, fast and can even be used to track subjects. This makes photography lenses a great tool for gimbal shots, where the focus can automatically latch onto a subject, and where it’s difficult and impractical to do manual focus pulls.

A disadvantage of autofocus is that sometimes these pulls can feel too quick or too electronic and less natural or organic than manual focus pulls. They may also latch onto the wrong thing, for example pulling focus onto a person’s hand when they make a gesture in front of their eyes during an interview. 

Cinema lenses solve these issues. 1st ACs will attach a wireless follow focus motor to the rods of a camera and line it up with the gear teeth on the lens. They can then use a handset with a rotatable grip to wirelessly and manually move the motor and focus gear to adjust how far or close the focus plane is. 

This puts control into the hands of a creative human being who can determine what is in focus as well as the speed and timing at which the focus moves from one subject to another. For example if you’re after a dreamy in and out focus effect that portrays the discombobulated point of view of a character.

Cinema lenses often have approximately a 200 to 300° focus rotation, compared to around the 90° or less of photo lenses. Being able to rotate the focus ring on cinema lenses more makes it easier to do more incremental and smoother focus pulls - especially useful when throwing focus from one subject to another or gradually bringing a subject into focus.

One main disadvantage to cinema lens focusing is that, because it’s operated by a human - even though it's a very skilled human - they are still capable of making mistakes and not hitting focus perfectly every time.

If you get a focus puller then you’ll also need extra gear: a monitor for the focus puller to judge sharpness, a wireless transmission system to send a video feed to that monitor, a wireless follow focus system, a base support for the camera with rods to mount the focus motor, and d-tap or 2 pin ports and enough battery power to run these accessories.

Not only do these accessories cost money to rent (or buy) but they also make the camera build larger and potentially make it incompatible with certain solo operator rigs such as smaller, prosumer gimbals.

To sum it up then: cinema lenses are better suited to an industry style shooting workflow which has the budget for camera crew and extra cinema gear, while photography lenses are generally used more for documentary, events or other solo shooting situations.

Having said all that, it is still possible to work with cinema lenses as a solo operator and manually pull focus on the barrel or with a manual follow focus - but why would you want to do that?

APERTURE

Now that we’ve covered focus we can move onto the aperture: the hole which can open or close to let more or less light into the camera. 

Most photo lenses have click stops. In other words, if you want to open the size of the aperture from f/4 to f/2.8 you’ll have to abruptly change from one to the other.

Cinema lenses however are de-clicked. This means the iris can be gradually opened or closed incrementally, allowing exposure to adjust more slowly and subtly. 

The reason this is important to some professional filmmakers is that they may want to do what is called an iris pull. This is where, just like with the wireless follow focus, a motor is attached to the iris ring which can be manually closed or opened. 

This can be used to change the stop during the shot to balance exposure without the audience being aware that this setting is being changed. For example, when going from a very bright environment like an exterior location to a very dark environment like an interior or visa versa.       

T-STOP VS. F-STOP

Another difference between cinema and photo lenses is how aperture is measured. Photography lenses will do so in f-stops, while cinema lenses use t-stops. Although these measurements are similar they do have a technical difference. 

F-stop uses a mathematical formula to calculate approximately how much light will reach the sensor. A t-stop is an actual measurement of how much light is let through, which includes the light which is lost inside the lens through reflections and glass coatings.  

This just means that cinema t-stops are more accurate.

Many modern prime lens sets will also have a consistent t-stop across all primes. 

Being able to shoot with all the lenses at the same wide open aperture means you can change a lens during a scene without the exposure of any of the shots changing at all and without needing to do any lighting tweaks.

Therefore cinema prime lenses with consistent stops can help you to work faster and more accurately.

ZOOM

So far, we’ve gone over the aperture and focus rings which all cinema prime lenses have, but cinema zooms also come with an additional ring which can be used to change the focal length of the lens. 

Photo zooms can do this by turning a section on the barrel of the lens, however they don’t have geared teeth. Cinema zooms can therefore be lined up with a motor and a device that can be attached to the tripod’s panhandle called a Preston Micro Force. 

They can use a button to set the speed of the zoom to be consistent: which makes it great for slow zoom push ins during a shot. Unlike photo lenses which are almost impossible to do a consistent speed zoom with by manually turning the barrel.

Cine zooms are parfocal which means the focus distance will remain unchanged even when the lens zooms in or out. Whereas the focus on many photo lenses will shift when you zoom - which means you may start the shot in focus but end out of focus.    

Another separating point between cinema and photo zooms is that usually the length of still lenses will elongate as the lens zooms and the elements inside are moved further away. Whereas with cinema zooms this movement happens completely internally, so as not to twist, turn or extend the barrel which may collide with or rotate a mattebox.

IMAGE STABILISATION

An added bonus that comes with many still lenses is they have image stabilisation. This makes it possible to just pop a lens on and shoot run and gun handheld footage on longer focal lengths with a much greater degree of stability. Unlike unstabilised cine lenses which will have more of a shake.   

LOOK

A final advantage of cinema glass is their look and colour reproduction. Of course it will depend on the lens which is chosen, but generally cinema lenses will have more consistent optical performance. Their flares will be a bit more cinematic and rounded. This is due to them usually having more iris blades, which makes the opening more circular compared to some photo lenses. 

Modern cinema lenses are designed so all prime focal lengths in the same set will render skin tones, contrast, and colour consistently.

Cinema lenses also come with a range of different looks from sharp, crisp, neutral and modern to more painterly, warm, vintage glass. This means filmmakers can choose a cinema lens with the visual characteristics which best suit their project.

The same can be said for many vintage photo lenses, the only difference being that this older glass will come without autofocus. Whereas vintage cinema lenses can still be controlled perfectly well by a focus puller.   

Modern cinema glass will create a coherent aesthetic when a movie is shot using different focal lengths. However, this is negligible when using many modern, high quality photo lenses - which should also produce pretty consistent visual performance.

CONCLUSION

Ultimately the choice between whether you shoot on cinema or photo glass comes down to budget, workflow and control.

If you need exceptional optical performance, to control the speed of the focus, zoom speed or do iris pulls during a shot, and you also have the budget, crew and resources to support this choice then choosing a cinema lens makes total sense.

However, if you’re doing a lower budget, solo, run and gun documentary, with a prosumer gimbal, need to move incredibly fast, not be tied down by heavy glass, and want the accuracy of touch screen autofocus, then using a photo lens would be the best choice.   

As ever, let your gear selection be guided by your practical environment as well as the kind of content you want to capture.