Red Raven Cforce plus motor calibration issue

[Harshad V. Gaikwad]

On a current shoot of music video I’m facing a bit of technical glitch around which I’m unable to get a solution and needed your advice.

 

Setup - Red Raven, Cforce plus motor, AMC-1, SXU -1

Issue - When calibrating the cforce motor, the motor rotates the lense in both directions, however at some point the motor disengages the wheel teeth from the lens ring teeth.

 

Tried two different cforce motors on 2 different lenses, tried to use various size wheels on cforce Motor, however the doesn’t work.

 

Tried to connect the cforce on both left and right side of the lens as well.

 

I’m unsure when’s I’m doing wrong, or missing some step. 

 

Your help and advice will really save my day.

 

 

[Kyryll Sobolev]

tighten the motor lock to the rod, and tighten the rod lock at the camera body

either one of those, or both, are loose enough to allow disengaging

otherwise, gently hold the motor to the lens while calibrating, to physically not allow it to move away from the lens

 

[Evan Walsh]

Does your setup use screw in rods as seen in some shape or zacuto baseplates? Screw in rods can be troublesome for lens motors, if that's not the case try calibrating on a lower torque setting. 

Do the lenses telescope as they move through the focus range? This can also cause motor issues if you're using a clip on matte box as the weight of the matte box will cause the focus mechanism to bind and the motors will kick off. 

If none of the above apply, try calibrating at a lower torque and as Kyryll said apply gentle force to the motor to keep it on the lens. Once it is calibrated you shouldn't have to worry about it hitting an endpoint and kicking off. 

 

[Harshad V. Gaikwad]

5 hours ago, Kyryll Sobolev said:

tighten the motor lock to the rod, and tighten the rod lock at the camera body

either one of those, or both, are loose enough to allow disengaging

otherwise, gently hold the motor to the lens while calibrating, to physically not allow it to move away from the lens

 Thanks for reply.

Alas the shoot is over now and had to pull focus without focusing system.

Had tried to tighten the rods, motor, also had held the motor gently to the lens, nothing worked.

But I’m keen to find a solution so I don’t face this issue in future.

Edited September 13, 2020 by Harshad V. Gaikwad

[Harshad V. Gaikwad]

1 hour ago, Evan Walsh said:

Does your setup use screw in rods as seen in some shape or zacuto baseplates? Screw in rods can be troublesome for lens motors, if that's not the case try calibrating on a lower torque setting. 

Do the lenses telescope as they move through the focus range? This can also cause motor issues if you're using a clip on matte box as the weight of the matte box will cause the focus mechanism to bind and the motors will kick off. 

If none of the above apply, try calibrating at a lower torque and as Kyryll said apply gentle force to the motor to keep it on the lens. Once it is calibrated you shouldn't have to worry about it hitting an endpoint and kicking off. 

 

Thanks for the reply. It were not screw-in focus rods. They were connected via wooden camera universal baseplate system.

Had tried all the torque levels faces the same issue. Was using canon cine prime lenses. 
 

 

[Kyryll Sobolev]

for stubborn lenses/motor/rod combinations, i have used an elastic band - wrap one end around the motor bracket, wrap the other end somewhere to the camera (evf rods), so the elastic bands are constantly pulling the motor into the lens