Follow Focus on Lens where barrel extends?

[Kevin Neal]

I have an Angenieux 16-68 lens that I'd like to use with a follow focus system, however when focusing, the barrel extends (external focusing?). If I add the gear ring, it seems like the teeth would lose their grip as the ring moves forward while focusing. Is there a standard solution to this? Maybe having the focus ring at a slight angle?

[Satsuki Murashige]

Either install a focus gear that is extra wide on the lens, or on the follow focus itself. Or a combination of both, if the extension is extreme.

[Kevin Neal]

1 minute ago, Satsuki Murashige said:

Either install a focus gear that is extra wide on the lens, or on the follow focus itself. Or a combination of both, if the extension is extreme.

Got it, that was my initial plan. Even with the wider gear wouldn't the teeth still lose grip due to the angle shifting though?

[Satsuki Murashige]

5 hours ago, Kevin Neal said:

Even with the wider gear wouldn't the teeth still lose grip due to the angle shifting though?

The angle of the gears should remain parallel, that’s why you need the wider gears. If they shifted angles, the gears would bind.

[Dom Jaeger]

As Satsuki said, there shouldn’t be a change of angle, a lens should extend along its axis.

But I have had to deal with lower quality follow focus units where there is play in the arm or the gear bearing and a wide follow focus gear can flex away from the lens gear. In that scenario, if you can’t have a wide gear ring on the lens and keep the follow focus gear narrow the only solution is a better quality follow focus.