I make movies sometimes.

I like to change my zoom and focus during the shot, like for a rack focus effect, or the ever-popular camera stunt, the dolly zoom or "Vertigo effect."

But I'm getting repetitive stress disorder from holding my hand funny around the lens barrel, and it's hard to adjust two rings with one hand while my other hand is holding the camera up.

I want a follow focus! And I don't want to pay several hundred dollars for it.

I saw recently an image and video of this way to make a follow focus out of hardware store parts... but while the design is simple, I couldn't find any instructions on how to make one. So I've written up my method so people can make their own.

Note:

be gentle with your camera. As with any mod, it's possible to smash your lens if you aren't careful, and I probably don't have to tell you that would cost a lot more to fix than the cost of a commercially-produced follow focus!

Step 1: What Is a Follow Focus?

In the olden days of cinematography (like 5 whole years ago!) almost all movies were filmed on film, with big giant cameras.

As a photographer/cinematographer, you know that tight control of the zoom and focal length is very important. Maintaining a shallow depth of field ("DoF") used to be very difficult with affordable cameras, and independent filmmakers still spend a lot of energy trying to get a "film look" and DoF on cameras with a small sensor.

However, lately you can shoot moving images on a digital SLR, which generally has a large sensor, and therefore is easier to get a shallow DoF. You can shoot cinema-quality footage by yourself with your SLR.

But wait - the subjects of images in movies MOVE. That is why they are called "movies." So you are going to have to adjust the focus to "follow" the person walking towards the camera, for example. You may even have to adjust the zoom at the same time.

This is where the follow focus comes in - on a big movie camera, you'd have a big expensive lens... and also a partner helping you, adjusting the focus coordinated with the camera operator's movements. This person is called the "focus puller."

It's a pain for the focus puller to be messing with the barrel on the lens all the time. So sometimes they'd get a knob to turn instead. This knob is the Follow Focus.

Your follow focus can be used by your friend the focus puller... or you (the camera operator) can use it yourself to make your camera adjustments easier to execute during the shot.

Step 2: The Ingredients

You will need:

your lens!
2 pipe clamps - these are big metal hoops with a screw on the side that lets you change the size with a screwdriver. Make sure you get a size that will fit around your lens!
two machine screws - the shallower the head, the better, because the screw's head will be between the band (pipe clamp) and each grip on your lens
the nuts that match the screws - nylon lined lock nuts optional
drawer pulls - I chose basic stainless steel pulls, but you could go for something more outré if you like

Tools:

a screwdriver
a way to cut the pipe clamps (I used aviation snips)
a way to drill a hole in the pipe clamps (I used a power drill and cutting oil)

OPTIONAL: prettification:

glue or threadlock
heat shrink tubing

Step 3: Size the Clamps

Before we start cutting and snipping, let's figure out exactly how big these things will be.

Gently place the pipe clamps around the grips on your lens, where you'd adjust the zoom and focus.

Tighten them with a screwdriver so they don't move, but NO TIGHTER - we don't want to put any stress on the lens.

Step 4: Fit Clamps to Lens and Mark

Now that your pipe clamps are on the lens, figure out where the handles are going to stick out. They can be anywhere you like. Mark the metal with a marker - I used a Sharpie.

I picked mine so that they'd not be in the way when I'm looking over the camera, in a place I can easily reach with my left hand without looking at the barrel.

Bear in mind the tightening screws may get in the way also, so be strategic where those end up too.

Also mark the range of movement for the band of the pipe clamp - you'll want to know which part of the strap is "extra" so you can cut it off later

Step 5: Mark Excess Clamp Straps

With your Sharpie, mark the range of strap on the clamp that is NEVER used - not when tight, nor when loose enough to remove the strap. This is so you know which part to cut off later.

Cut off the excess strap with whatever you like

a hacksaw
aviation snips / tin snips
angle grinder

Step 6: Prepare to Cut and Drill

I recommend marking the spot where your handle will stick out with a scribe or other cutting device. This is so the drill doesn't wander over the surface and make a mess of your pipe clamp.

I also took this opportunity to mark the insides of the two clamps, so when they are finished I know which is which.

Drill those suckers!

Remember to use cutting oil so you don't ruin your drill bit.
use a drill bit slightly larger than your machine bolts

Step 7: Assemble Bolt and Fit

This is pretty self-explanatory, but here goes:

stick the machine screw through the pipe clamp, with the head on the inside
fasten a nut as tightly as possible to the outside
attach your knob on the end

You're done!

Or... are you?!

Step 8: Optional Finishing: Glue the Bolt

Maybe I'm pretty rough with my gear, but it seems like the nuts were constantly getting loose. Very distracting during a shot!

One solution might be to use a nylon-lined lock nut. That would have been a prettier solution, but still not foolproof.

So I glued the nut to the bolt. I used Gorilla Glue, but there's also several products for this exact purpose, like "threadlocker."

The glue is messy, so don't do this anywhere near your lens. Trim the excess glue afterwards.

Step 9: Optional Finishing: Heat Shrink Bolt

Silk purse? Sow's ear? Maybe both?

Having a screw stick out of your camera is "so over." If you add a piece of heat-shrink tubing it looks almost store-bought.

Step 10: Profit!

Install those suckers -

now the hard part: practice! Changing two levers while running the camera is still pretty tricky, but at least now it's physically possible!

Good luck!