Thread: DJI Follow Focus - ISSUES (Red Helium)

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  1. #1 DJI Follow Focus - ISSUES (Red Helium) 
    Junior Member
    Join Date
    Apr 2020
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    5
    Hey Guys. Been using my Red Helium set up for a few weeks now. Recently needed Follow Focus so I opted for the DJI follow focus. Worked pretty well for a few shoots but recently I found that the focus was almost slipping off of the ring thread. The lenses I use are the Leica R, cine-mod'd, focus ring and everything. Might be important to note that I have trouble calibrating the focus, I have to do the manual-hand option, instead of the automatic that is (supposed to) work. Also, the focus device slips minimally, but does effect the shots, so for instance, it will no longer go down to the minimum setting, or the maximum setting, makes me wonder if it's actually "slipping" or if the motor is off. Doesn't seem to effect the performance but I will also use a Polar Pro ND filter mount at times, they're pretty light though so can't imagine that's it. Any advice or workarounds/troubleshooting would be great. Thanks!
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  2. #2 DJI FF 
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    Join Date
    Feb 2013
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    Vancouver BC
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    63
    Might be good to update the firmware and check the screw that keeps the focus wheel on... sometimes it doesn't thread correctly and can cause things to feel a little wonky.
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  3. #3  
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    Join Date
    Feb 2012
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    A few years back when Noah was a pup we had a C-Motion focus system on a SI2K camera. Nikon primes with metal focus gears were a dead loss. The motors are powerful. They have to be.

    During calibration, at the end stops, they would overtorque the gears around the lens barrels no matter how firm the set screws in the gears were. With the proper S16 primes, there was too much compliance in the rails which allowed the focus gears to nearly walk out of mesh and there was lost movmenet in the twisting. It was all enough to upset the calibration.


    Some things you might try :-


    If there is a lot of flex observed, add one or more bridgeplates or lens supports on the rails and make sure they are set tight in order to stiffen the rails. If they interfere with the lens you are using, turn the lens supports upside-down. Lens support bridges need to have a broad footrpint on the rails and also need to be the fully enclosing, not the saddle and plate clamp-on type or you will gain nothing except weight.

    Paint a spot of white-out on the focus gear/lens barrel junction as a matchmark between the gear and the barrel. Let it dry. Operate the follow focus then check the matchmarks to see if the lens gear has moved on the barrel. I am not familiar with the Cinemod system. To avoid follow focus problems, the lens gear on the Cinemod Leica may be actually machined into a new lens barrel. In that event the fault will be in the follow focus system or the supports.

    Modifications which add a pressed on delrin or metal gear with friction screws on radial centres will slip around a lens barrel. There is a limit upon how much you can tighten the screws before you damage the lens barrel or distort it enough to jam the movement.

    When you set the focus gear against the lens gear, make sure that any bending or springiness is taken up by using thumb against the arm at the pivot point and finger against the lens to preload the lens mount and the rails before tightening the arm. That is a poor workaround but may help avoid the gears walking out to loose mesh or out of mesh and skipping a tooth when you operate the follow focus.
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