Instructables
Picture of DIY $4 follow focus for SLR
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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!
 
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Step 1: What is a Follow Focus?

Picture of 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.
emaxon1 year ago
Just as easy, more robust than this, but a $20 project when all's done, you could use "heavy duty" stainless band clamps, often used on trucks, heavy industrial equipment, that are tightened with a tangent bolt that gathers the two free ends of the band, instead of a captive worm gear that takes up the slack. Since they are already tightened with a bolt, all you need to do is replace the included bolt with a long one, (or threaded rod) of your choosing to fit your knob, and tighten the assembly with 2 nuts, counter-tightened as sandkvist suggests. With this style clamp, you'll have a much more rigid assembly when tightened, where the long bolt won't be so prone to flexing the clamp. Any truck parts supply house should carry this style clamp. McMaster Carr also carries a good selection, in your choice of 430 or 304 stainless: http://www.mcmaster.com/#standard-hose-clamps/=o4u7iy You may find one that comes with a 1/4-20 bolt to fit your knobs, but it will more likely be tightened by a 5/16 or 8mm bolt which won't fit your knobs. If so, maybe socket head cap screws will be pretty enough, or you can use knobs made for the larger thread. You may also get away with a partial thread long bolt, (easier to find,) depending upon how wide the gap is in the open clamp. Thanks for posting!
monkeywidget (author)  emaxon1 year ago
I'd love to see photos of something like this! Maybe my next version will use this.
darkblood1 year ago
I find that putting several wraps of teflon plumber's tape on the screw before tightening the nut keeps it from working or vibrating loose, but is much less messy than glue. Since I almost always have a roll or two in the toolbox, it seems like the easy answer.
May I suggest, to protect the lens from scratching:
Countersunk screws,
The hole dented outward to accomodate the screwhead, (with a centrepunch onto softwood),
Nut face countersunk to match,
The ring itself encased in heatshrink.
I was going to make this exact post! Both points (countersunk screw and heatshrink wrap) are on point.

I was also going to suggest putting another handle on the other side to counterbalance the handle. The heavier the knob, the smoother the motion will be. However, if the knob is too far off center, gravity may pull it on around. Putting a second identical knob on the other side (or with no extending rod, a weight that is much heavier to overcome the leverage) will keep your setting no matter where it is in the rotation.
Protip: If you are using a tripod, pull those knobs around using a rubber band. It's EXTRA smooth. This trick is also great for a professional-looking pan shots.

http://www.youtube.com/watch?v=Fj6fMcJ18aA
sandkvist1 year ago
You could simply counter the nuts instead of gluing them. Tighten one nut like you did and add another nut ontop of the first, and tighten them towards eachother. Now you got a simple counter locked nut
monkeywidget (author)  sandkvist1 year ago
very true. Thanks for the idea!
Continuo1 year ago
Nice project.
you can use nailpolish as thread locker (it's almost exactly the same stuff as the regular loctite). just put a drop on the the screw where you want the nut to end up, and then tighten the nut through the drop, and finish with another drop on the outside.
Several benefits to doing it this way: it dries quickly, easy to clean up, easily removed, readily available for cheap/free, and comes with a brush suitable for controlled application.
I disagree with the assertion that nail polish is almost the same as regular loctite. That may be the urban myth or what someone you trusted told you, but I can't let it be propagated on this site that tries to help people build things. Many years ago they used to use something that looked like (and may have been) nail polish. But that was a marker so you could tell if the screw had loosened or been tampered with. If your screws are loosening then get some real thread locking material. (or a lock nut or use a jam nut) A small bottle isn't that much and will last your lifetime. Ask the sales person for help as there are many kinds. The goal of this site is to encourage people to come up with novel ways to solve problems but I hope we can also help them learn to do it the right way.
Rather dramatic considering the project, don't you think?
OK, I'll give you that.
XardoX1 year ago
You can use a ring of EVA Foam in between the Clamps and Lens to protect the lens from any damage...

Thanks for the idea, working on it :D
May I suggest, to protect the lens from scratching:
Countersunk screws,
The hole dented outward to accomodate the screwhead, (with a centrepunch onto softwood)
The ring itself encased in heatshrink ?
mickryobe1 year ago
This is an excellent idea.
May I suggest some kind of padding between the pipe clamp and the lens.
A marred lens will have lost most of its trade in.resale value.
dieferman1 year ago
Simple , But Great Idea !!!!
Thanks For Sharing !!!!
You are genius
Nice job !
Instead of gluing the bolt, which seems somewhat messy, maybe a drop of locktite would work better ?…
bwh131 year ago
Sweet build: simple, cheap, effective, & well written