This guide will show you:
- What a follow focus system is,
- Why you need a follow focus system,
- What they are made of, and how to get the best out of them,
- What to look out for in a good follow focus system,
- Suggestions for different budgets and camera systems.
The art of focusing
One of the cheapest and most versatile lens in any manufacturer’s repertoire is the 50mm lens. Look around, almost every lens buying guide will recommend you get a ‘nifty fifty’.
The f/1.4 and the f/1.2L have similar sized focusing rings, while the f/1.8 has a thin flimsy ring also known popularly as ‘a joke’. The position of the focus ring on all three lenses are different.
The major draw for all these lenses is their aperture. Assuming an APS-C or Super 35mm sensor focusing at 10 feet;
- At f/1.8, the depth of field (DOF) is about 0.8 feet (10 inches).
- At f/1.4 the DOF range is 0.65 feet (8 inches)
- At f/1.2 the DOF range is 0.54 (6.5 inches).
If you’re shooting video at these f-stops, and your subject leans, turns or moves, you’ll have a hell of a time using the focus rings on these lenses to follow them around. On a large display or cinema screen, any focusing mistake can’t be hidden. 4K makes it worse.
So, what’s the point of a cool 50mm f/1.8 lens if you can’t shoot at f/1.8? One way to get around this problem is by using autofocus (AF). However, filmmaking is not always about documentation. You might want to rack focus (move focus from one point to another) at any time for various reasons.
In the professional video world, you need a system that is consistent enough to deliver at every turn. The bigger the production, the greater the cost of each take. How many takes can you screw up before you are kicked out?
Traditional high-end lenses made for film cameras and digital cinema cameras have good focusing rings. Older manual still camera lenses also have good focusing rings (there was a time when auto focus didn’t exist and people still got the shot). Newer lenses, especially the smaller semi-plastic variety, have the worst focusing rings seen in history.
If you are okay using autofocus, fine. If you are zen master who can pull focus day in and day out on a 50mm f/1.8 plastic lens at f/1.8, respect.
For everyone else, there’s the follow focus system.
What is a follow focus system?
A follow focus system is a set of parts that work together to help you focus more precisely and conveniently for video work. It’s primary function is to allow focus to follow the action.
The technique of following the action using a follow focus system is called racking focus or pulling focus. The person who is an expert at pulling focus is traditionally called the focus puller. This person is an integral part of the camera department and is usually also the First Assistant Cameraman.
The question you need to ask yourself is: How much more of a benefit does this contraption provide over the focus ring? The rest of this guide will attempt to help you find the answer to this question.
The parts of a follow focus system
The most visible part of the follow focus system is the white disc and knob that people turn. However, there’s a whole lot more going on. The only way you can judge the merits and demerits of any particular system is by observing its parts. To do that, you need to know what they are.
Here are the generic and typical parts of any follow focus system:
- Rail clamp or mount or bracket
- Lens gear ring
- Focus knob
- White disc
This is the part that attaches to the two rods that form the base of any camera rig. This means, you will need two rods and a base plate to set up this system correctly. Right here you have three options:
- 15 mm rods, spaced 60 mm apart*
- 15 mm rods, spaced 100 mm apart
- 19 mm rods, spaced 104 mm apart
*All distances are center to center.
Some systems come with multiple options, but the cheapest ones come only in one standard – 15 mm/60 mm spacing. This is the most popular standard nowadays, since cameras have become lighter and smaller. However, you need to know the entire size and weight of your rig to decide which rod system is right for you, and this dictates your choices. To know more about finding the right balance and size of your rig, read Laying Out the Rig.
The arm can either be rigidly attached to the rod clamp or can be flexible. As a rule of thumb, you must aim for the most versatile arm possible, because this will allow you to work with different kinds of lenses and systems. At the very least, you could look for an arm that moves laterally, so you can push the system outside or inside a bit to accommodate the size of the lens. If possible, you should also get an arm that pivots, for the same reason.
Adding these movements has one disadvantage though, and that is, the arm has more moving parts. This can lead to failure over long periods of abusive use. More on this later.
The gear attaches to the arm, and is rotated by teeth that connects directly to the focus knob. This is probably the most important part of the entire follow focus system. You can have 1-to-1 gears, which will give you the same ‘throw’ (the degrees that the lens can be rotated) as the focus knob.
Sometimes, you might want a larger throw, which means, for a smaller turn of the focus knob you want a larger turn of the focus ring on the lens. This is useful when you want to turn the focus ring from one extreme to another, but is tough to pull off with just one wrist action. There’s another solution to this problem, which we’ll see below.
On the other hand, you might also need a shorter throw, which means, for a smaller turn of the focus ring you’ll need a larger turn of the focus knob. This is useful when your focus marks are spaced finely apart, and you need greater precision and smoothness of focus.
Finally, some systems allow you to move the gear from left to right, so you can adjust for lenses who have focus rings that turn in the ‘other’ direction. This also helps to adjust the entire system forwards or backwards on the rig in proportion to the lens and camera body.
Each focus puller is different. What one might find perfect another might hate. Add to this the different kinds of shots that demand different throws. Having the option to manipulate the throw of the gear is one of the most important features you need to look out for. This allows the focus puller to ‘tune the system’ like a musical instrument. Cheaper systems only offer one throw and gear.
Lens gear ring
The gear connects to the gear ring. The gear ring wraps around your lens tightly, exactly on the focus ring. Sometimes, you might work with lenses with focus rings that already have teeth, in which case a gear ring isn’t necessary. In any case, it’s a handy thing to have. If you work with many kinds of lenses, you’ll find that you need more than one type of gear ring, and this might mean purchasing it separately to suit your lenses.
Needless to say, the pitch of the teeth (distance between each groove) must match with the pitch on the gear, for the smoothest action.
The focus knob is what you turn to focus, just like the focus ring. You normally turn the focus ring on a lens by keeping your arm perpendicular to the camera, and this isn’t a very convenient action for video. The focus knob on the side allows two major benefits:
- You can keep your arm on the side in a more comfortable position.
- The focus puller can pull focus and be out of the camera operator’s way.
On more expensive follow focus systems, you’ll find the knob can be attached to either side, for left-hand or right-hand use. You might also find systems that allow you to change the rotation, both clockwise and anti-clockwise. Some systems also allow you to lock in hard stops, for limited movements.
The focus knob has a fixed orientation marking (usually at 12 o’clock), either a white dot or a physical protrusion, that allows you to mark focus on the white disc.
This is another critical part of the system. If the material used on the rim is of good quality, you can:
- Write on it,
- Read what you’ve written easily,
- Erase everything leaving no trace,
- Do this a million times and still have a shiny white disc.
What do you write on it? We’ll see in the next section.
The above parts form a typical follow focus system. The following parts add quite a bit of functionality to the generic system:
- Focus Whip – this is a wired remote focus system that attaches to the knob (if it has the connector) and allows the focus puller to be completely out of the operator’s way. It’s very handy if the operator has to move around.
- Speed Crank – sometimes, you want to quickly rack focus across 360supo/sup. This is very hard to do on either focus ring or focus knob. For this reason, you attach a crank to the focus knob for faster turning.
- Additional gears – you can speed up or slow down the throw with additional gear systems.
- Wireless follow focus systems which allow you to control focus remotely.
In addition to all of the above, you also need two support tools to make all of this work:
- Some kind of measurement device
Let’s see how all this ties in together.
How do you use a follow focus system?
The first thing you do is look for the Greek letter Phi (?) on your camera, as shown:
You won’t see it on DSLRs, because DSLRs have autofocus and live view manual focusing.
Once you’ve located the ? mark, you need to measure the distance from this mark to the point of focus, using a measuring device. This could be one of three things:
- For small distances (1-25 feet) – a heavy duty Steel Measuring Tape with locking mechanism. For tapes less than 15 feet in length, a 1/2″ width is okay. For anything greater, look for 1″ wide tapes.
- For larger distances (10-300 feet) – a Fiberglass Tape Measure. Most lens markings stop before 200 feet. Instead of carrying one tape roll, I suggest you carry two. You can carry a 50-foot roll and a 300-foot roll, and only use the larger one when necessary.
- For large distances or out of reach areas – a Laser or Ultrasonic Rangefinder that goes about a 100 feet, but be careful. Never point the laser at the camera (or another human being) or you might fry your sensor. Stay within the legal laser specification limits (it varies per country).
If you are following humans, you usually measure from the ? to the eye, as follows:
You turn the focus knob until this distance is indicated on your lens (as shown above – not all lenses have focus distance markings, and some of them are not accurate!). Then, mark this spot (use the orientation marking on the focus knob) on the white disc with an erasable marker. The Staedtler Marker is great for focus marking. If you can’t find the exact model, search for ‘dry erase marker’ and use a reputable brand. The eraser is as important as the marker.
If you have more than one focus point, then measure each position and then mark all of them one by one. The convention is to mark them in numbers (1, 2, 3, etc.) in the order of the character’s movement on set. This way, the focus puller can pull focus by looking at the markings, while also having an eye on the monitor (if available). If more than one character is involved, you can try different colored markers.
All said and done, a focus puller’s job is not entirely mechanical. You have to watch the actors and anticipate their movements. Racking focus also means following the actor from one focus mark to the next. The actor might move at two varying speeds in different takes, and you have no choice but to match their movements. This kind of skill only comes with experience.
Having a monitor is definitely a safety net. Ideally, you’d want a monitor that is greater than 10″ for 1080p and 24″ for 4K (if you can find a 4K monitor at that size!). Other functions like focus peaking are also welcome.
It goes without saying that the following links in this chain must be accurate:
- The measuring device.
- The camera assistant who measures. You can’t afford to be lazy or distracted.
- The distance markings on the lens.
- The gear mechanism on the follow focus system.
How do you decide if you need a follow focus system?
Ask yourself these questions:
Are you shooting at large apertures with shallow DOF on a regular basis?
Is your production devoid of an external monitor with good resolution?
Is there a lot of movement, either by the talent or by the camera?
Are you shooting for broadcast or the silver screen?
Are you shooting 4K and above?
Are you using cheap semi-plastic lenses with poorly constructed focusing rings?
If the answer is yes to any of the above questions, your production will greatly benefit from a follow focus system.
Does a follow focus system offer more stability than focusing by hand?
Simple two-finger focusing (your hands only) gives two points of contact on the lens.
A follow focus system has four:
- Where the gear contacts the gear ring or focus ring.
- Your two fingers on the focus knob.
- Where the teeth meet the gear.
This doubles the chances of instability. The only way this can be overcome is by using a precise mechanism that is also rugged enough to work smoothly, without error, for years. By using a well designed, precisely machined follow focus system that does not compromise on its parts, you eliminate the effects of the last two points of contact, and in that case a follow focus system will have only one point of contact. Take his one step further with a focus whip or wireless follow focus system, and you really only have one point of contact.
To answer the question: Yes, a follow focus system is more stable than focusing by hand, if there are no ‘loose joints’ or misalignments anywhere.
What to look for in a good follow focus system
Look for these things:
- Geared focusing mechanism for finer focus throw.
- Rigid construction to limit vibration.
- Allows a second person (focus-puller) to pull focus by standing out of the camera operator’s way.
- Clear white disc for erasable markings. If possible, it should be bevelled for better viewing.
- Precise machining with no ‘bumps’ in the movement
Want a cheap follow focus system? You’re better off without one. I know this is a little hard to swallow. When you don’t have the money you must compromise on cheaper alternatives. The good news is, there are cheaper brands available today that have passed the test of time and abuse. Don’t go by sample videos of systems that work great when new. Make absolutely sure you can find at least three people who have been using the same system for over a year in a professional environment.
Also look at the availability of parts. If something fails, what are the odds of finding a replacement soon? Secondly, many new manufacturers copy the latest designs, and might not have parts for their older models. You need to have a level-headed attitude here. Ask yourself: Is the manufacturer out to make a buck or do they really invest in follow focus design? What are their design principles?
Rule of thumb: Never, ever, settle for a cheap follow focus system that does not guarantee perfection over years of daily use.
The more expensive options are not only built to last but also fit on all kinds of camera and lens systems. A good follow focus system is a worthy investment. Compromise on something else. Here’s a quick comparison video that will help you understand a few of the things we’ve discussed so far:
Follow focus system suggestions for different budgets
These are just general suggestions or guidelines. Don’t take them as recommendations.
At the time of this writing the minimum you should expect to spend on a follow focus system is $100, and these are risky solutions. Some of them have been around for a while, and have garnered sufficiently positive reviews.
For $600, take a look at the Genus G-SFOC Superior Follow Focus System, a good all-round system:
Check out this review of the Genus G-SFOC Superior Follow Focus System:
The Genus is not very versatile, though well-built. For more versatility, and for less than $1,000, check out the Letus Follow Focus system (video earlier in this article):
You can see the difference in materials, construction and versatility in the first three choices. In regular use, the difference in ergonomics is very noticeable.
Remember: Solidity gives you confidence.
Between $1,000 and $2,000, check out the Arri MFF-2 Follow focus system:
The MFF-2 has interchangeable focus knobs and is available in two different bases: a cine style base and an HD version that utilizes a 1:1 gear ratio for lenses with a shorter throw (such as EF lenses).
Here’s a video from AbelCine that explains this:
If you’re looking for a follow focus system that can be mounted on multiple rod systems, look at the Cavision RFF1560G or RFF-15D which comes with adapter brackets:
For a great wireless follow focus systems, check out these options:
To know more about wireless video production, read Understanding Wireless Video Production.
Without real-world experience it is almost impossible for anyone to understand why the pros use expensive gear. Nobody wants to pay more for something that can be accomplished for less. It’s the little things that newcomers miss. Hunt for them!
If you are committed to years of digital cinematography, why not invest in a good follow focus system? These are meant to be long term investments, and the good ones will fit most lenses you throw at them. Cheapen out, and your project or career might just be thrown out of focus (bad pun intended!).