5 Reasons Why Zoom Lenses Are Better Than Primes

INTRODUCTION

As we saw in a previous video, there are many reasons why in some photographic situations prime lenses are a better choice than zoom lenses. The fixed focal length or magnification of prime lenses provide: a more considered perspective when choosing a focal length, better overall optical quality, a larger aperture, a smaller size and better close focusing capabilities.

In this video let’s flip things in favour of our variable focal length friends by unpacking five reasons why zoom lenses are better than primes.  

1 - ZOOM MOVEMENT

The first reason for choosing to use a zoom lens goes without saying - it allows you to do a zoom move in a shot. Most shots in cinema and other kinds of film content shoot with a fixed level of magnification and do not zoom during a shot. 

I think this is in part due to the traditional language of cinema built by a legacy of many older films which were photographed with prime lenses, before usable cinema zooms were widely manufactured and prime lenses were the de facto choice. 

However, during the 1970s and 1980s using in-camera zooms to push into a shot or pull out wider without moving the camera gained more popularity amongst filmmakers. 

There are many stylistic motivations behind using zoom movement. It can be used to slowly pull out and reveal more information in a shot until we see the full scope of the landscape. It can be used as a slightly kitsch, crash zoom - where the camera rapidly punches in to reveal a character, to emphasise a certain line, or land a comedic punchline.

Because of their flexibility and ease of use, which we’ll come to later, zooms have also been widely used when shooting documentaries - particularly fly on the wall type doccies. In some films this type of zoom movement is extrapolated from these documentary conventions in order to lend a visual style of realism associated with the documentary look, or even to mock this look for comedic emphasis.

The list of reasons to zoom within a shot goes on and has a different stylistic or emotional impacts depending on the context in which it is used. It should be noted though that most filmmakers are careful about not overusing zooms, as they can easily become a bit tired, distracting and cliched, unless they form part of an overall considered visual style.          

2 - PRECISE FRAMING

Of course pushing in with a lens requires a zoom, but what about those films that don’t use any in shot zooms but still decide to shoot on zoom lenses?

Another reason cinematographers may use a zoom is because they make it easy to precisely frame a shot. 

When you shoot with a prime lens’ fixed focal length on the camera and you want to change the width of the frame you need to physically move the position of the camera. This is easy when you are shooting handheld with a little mirrorless camera. 

But when you are using a hefty cinema rig, on a head and a set of legs that is so heavy that it requires a grip team each time you move and level the camera, using zooms becomes more appealing. 

With primes you may need to slightly reposition a frame by moving the camera forward six inches, realise this is too far forward, and then have to move the camera back again three inches until that light stand is just out of frame. With a zoom lens you can just just change the focal length from 50mm to 45mm without moving the camera or tripod.

A great example of this happens on most car shoots. I’ve worked as a camera assistant on loads of car commercials and about 99% of the time when using a Russian Arm to shoot moving vehicles, DPs choose a zoom lens over a prime lens. 

It’s far easier and more practical to use a wireless motor to adjust the zoom on the barrel of the lens to find the correct frame from inside the Russian Arm vehicle, than it is to get the driver of the vehicle to keep repositioning the car a couple of metres on every run until the frame is perfect.

It is also easier to find the correct position for the camera without needing to move it when using wider primes: either with a pentafinder, a viewfinder app, or just based on the experience of the DP. But, when you use longer focal lengths, like a 135mm or 180mm prime lens, because of the lens compression it becomes infinitely more difficult to find the correct frame without needing to move the camera. 

There are also less prime focal length options at the longer end - which we’ll talk about later. Therefore for telephoto shots, zooms are regularly used for their ability to punch in or out until the correct frame is found. 

3 - FASTER SETUPS

With an increased precision in framing shots, comes a faster set up time. On a film set time very much equals money. The quicker you can set up and shoot each shot, the less crew overtime, rental days on gear and location fees you have to pay.

When you’re working on a tight budget without the possibilities of extended over time or extra pick up days, taking longer to set up shots means that the director is afforded to film less takes, with less time to craft the performances of actors or set up choreographed action.

Using zoom lenses speeds up production in a few ways. For one, if you shoot everything with a single zoom lens, it means less time spent changing lenses, swapping out matte boxes and recalibrating focus motors.

As we mentioned previously, it also means that grip teams don’t need to reposition heavy and time consuming rigs, like laying dolly tracks. If the track was laid a little bit too far forward, the operator can just zoom a little bit wider on the lens to find the frame, rather than starting over from square one and re-laying the tracks.

Another practical example is when using a crane or a Technocrane. If you use a 35mm prime lens on the camera, balance it on a remote head, perfectly position the arm and then realise that the lens is not wide enough and you need a 24mm focal length instead, the grip team needs to bring down the arm, the camera team needs to switch out the lens, the Libra head technician needs to rebalance the head with the weight of the new lens, and finally the grip team then brings the crane back into the correct position. All this could take 10 minutes or more. 

If instead the DP used a zoom lens with a wireless focus motor on the zoom, this change would take less than 10 seconds.

10 minutes may not sound like a lot, but if this keeps happening throughout the day this can quickly add up to an hour or two of wasted shooting time - which is both expensive, means less footage will be shot and therefore gives the director less precious takes to work with in the edit. 

4 - FOCAL LENGTH OPTIONS

A prime lens set usually covers a fair amount of different focal lengths on the wide end, but, when it comes to telephoto options beyond about 100mm their selection is usually very limited.

For this reason, DPs that like shooting with long focal lengths that compress the backgrounds in shots often hire a zoom. For example, the Arri Alura can punch in all the way to 250mm. While the longest focal length available on a set of modern cinema prime lenses such as the Arri Master Primes is 150mm.

So for cinematographers who want to use long, telephoto lenses, zooms are usually a better option. 

Many zooms also offer an overall greater range of focal lengths, for example an Angenieux 12:1 zoom offers a field of view all the way from a wide 24mm lens up to an extended 290mm compressed field of view.

For shoots that are in remote areas or in locations which cannot be accessed by a camera truck, carrying around a full set of spherical primes in three or four different lens cases is far more logistically challenging for the crew than just putting a single zoom lens on the camera and walking it in to set. 

This makes zooms far more flexible and practical when compared to primes, especially sets of older vintage prime lenses, such as the Zeiss Super Speeds that only come in 6 focal length options from 18mm to 85mm.    

5 - BUDGET

The final reason may seem a little counterintuitive because when you compare the price of a single prime lens with that of a single zoom lens, the zoom lens will almost always be more expensive. 

However, prime lenses are almost never bought or rented as individual units. They come in sets: such as a set of 6 lenses, or a set of 16 lenses. 

When the rental price or buying price of a full set of primes is tallied up it is almost always more than that of a comparable, single zoom lens that covers the same amount of focal lengths.

Therefore, when the budget of a shoot is a bit tight, it may come down to either pleading with the rental house to break up a lens set into a very small selection of two or three primes that cover a limited range of focal lengths, or hiring a single zoom that you can use to cover every field of view that is required for the shoot.

In this regard, a zoom lens is far more realistic and practical.