Jedy

The lens only moves whilst focusing. I believe the torque from the follow focus (it has to be fairly tight to remove any play in the follow focus) is pushing against the lens causing it to move. The cheap gear ring belt may not be helping either for all I know but I don't want to invest in a pricier lens gear solution if it turns out not to help. Thanks for all the suggestions. I'm aware dslr's were never originally intended for video work and in many ways are not ideal. I am going to borrow another lens support which should fit my rig better than mine and will see if it helps.

Unfortunately the lens support I have isn't very effective, plus it gets in the way of the mattebox.

I have a 5DmkIII and Canon 24-105mmL and 70-200L, both f4. I purchased a good quality follow focus earlier this year (from shoot35.com). The issue I'm experiencing is the dreaded lens wobble when engaging the follow focus (the lens physically moves). I assume it's caused by the follow focus torque as moving the focus ring by hand doesn't cause this problem. I am currently using a cheap gear ring belt on the lenses. As the photo below shows, the drive gear is very small. The company offer bigger drive gears at additional cost. I am hesitant right now in simply buying anything on the slim off chance it solves the problem as I have wasted money in the past this way. Of course I'd spend money if I knew it would help solve the problem. I am looking to invest in an external monitor/recorder (Atomos) this year as investing in a proper film camera is out of my reach right now and this issue pretty much makes my rig unusable. Any help/advice would be greatfully received.