Hello fellow Pullers, I am having an issue I'd like to share and seek advice on. I am on a two camera setup show. Alexa mini, latest stable SUP 5.4, both with SXU hand units and Arri Cforce Plus motors connected to LBUS. Cooke S4/i and S4 mix. On prep a couple of days ago, we started having an issue on one of the cameras, where whenever the system/motor was first initialized it would ask for calibration, as it does, I'd press calibrate (on hand unit or on motor), it would start it's thing going towards both ends of the lens, however, when it reaches the second end, instead of settling and being ready to work with the range mapped, it stops right there at the edge of the second limit of the lens and suddenly goes on to ask for calibration again as if it didn't have just did that. This loop went on for a while. We lowered torque to minimum and then changed radio channels. Eventually it came back to normal operation. On the same moment that A camera went normal, B camera started doing the same thing. I fiddle with torque for B cam motor and it seemed to settle after a while. The problem is that, on our testing day, A cam started doing it again, (can't tell now whether they moved torque up again, I was on different location) so A cam dropped the Wireless and went FF5 for the rest of the test. Today is day off, but we are now weary of having this suddenly coming up during a shot as principal photography commences tomorrow. Although the changes on radio channel seemed to help fix the issue, honestly, I don't think it is related, and I am more geared towards either a problem on the reading process (maybe due to high torque, although S4/i are smooth as butter). It happened with 3 different SXU hand units and 3 different motors (2 cforce plus and one mini). I truly appreciate any insights as to properly identify why this is going on and find a reliable fix, other than moving to other system which is unfortunately not an option due to budget constrains. One more info I think is relevant. The motors were all set up in a position as to minimize excessive force on either end, that is, having an imaginary line crossing the centre of the rod and the tangent to the gear/lens interface. Fingers crossed here for any insights. Have a great week everyone and thanks for having me here.
Could be a power issue. Have you tried to power the motors directly from a Ptap?
Thanks for your input Clemens. No we haven't tried that, unfortunately the rental house doesn't have that cable. Only the 4pin lemo-lemo motor to Lbus, but I agree it may be a power issue so I will keep that in mind and make sure our onboard batteries are monitored if it happens again :)
Do you have LCube on the camera/daisy chain? And are you using Wifi on the cameras/is it turned on?
Hi Gustav, thank you for pitching in. We don't have LCube, nor UMC or AMC. the motor is wired straight to the LBUS port on the Mini, so the hand unit is communicating to the camera/motor through it's onboard wifi system. I did get some feedback on another forum on facebook, where fellow pullers suggested that it may be a power issue (although we think that one cforce mini only shouldn't cause any major issues) but it might be related to the quality of the batteries on our kit, where maybe some are older and may not be holding enough Amps when the voltage drops. We are also sourcing a P-tap-lemo4 cable to act as a supplementary power source. We will monitor that to see if we can be conclusive. Also we are considering re-setting or even turning off LDS completely as it is known to have issues with some Cooke S4/i, since we don't need lens metadata on our workflow. Another suggestion comes as to check region settings for the wifi radio. For now, this is it. We will kick off tomorrow, but not before I can double check all the above. Unfortunately, today we are off with no access to the kit. Thanks again for your concern.
Hi Andre, try turning off LDS completely in camera.
I came across the same issue a couple weeks ago on a commercial shoot prep. Alexa Mini, Arri Master Primes, SXU-1 with a single cforce mini powered via LBUS.
I noticed that in the ECS menu the lens data was intermittent, some lenses it read fine and stable but one in particular (I think it was the 75mm) would communicate for a moment and then disappear during motor calibration. Triggering the motor to ask for recalibration.
I believe its a communication issue between the lens and camera, possibly via bad contacts? Assumed to be a lens contact issue as only one of the lenses exhibited this... Unsure. In the past I've had to clean both camera and lens mounted contacts with isopropyl to re-establish communication and lens power, in this instance that didn't work.
Thats all I got! Ended up just turning off LDS entirely. Didn't need it on this gig, hopefully it doesn't happen on a gig where I need it for lens power or metadata logging.