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.
- 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?
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.