HU3

60 threads in the archive

Based on 60 threads · 27 cited

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The HU3 is Preston's handset, and it runs on standard Sony M-style batteries, rated at 6 hours per charge with M-Series packs 23 24. It pairs with an MDR2 once the G3 board is swapped for a G4, and if your signal keeps dropping, suspect interference or crowded channels near your MDR first 10 6 7. If your lenses won't map, check for a non-linear lens, a flexing motor mount, or a lens that needs its own calibration 17 18 19.

The questions 8

Where can I get my HU3 repaired, refurbished or repainted?5 threads · latest 2022

In short

The only lead is a technician who refurbishes Preston HU3 units by painting, per a 2022 thread 1. That thread gives no location, cost or turnaround, so you have to ask 1.

How the pros do it

Find the technician from the 2022 Follow Focus thread who refurbishes Preston HU3 units 1.
Expect paint, not anodizing, from that technician 1.
Ask about cost and turnaround before you ship anything, because the thread gives neither 1.
If you want anodizing, a 2014 job re-anodized a hand unit in rust for theft recovery, including disassembly, sanding, anodizing and reassembly, at roughly 1000 units of currency 2.
If the HU3 screen won't power on, open it, push the ribbon cable firmly into its connector and check the other internal connectors 3.
Use a local service center if you have one, because repairs can take hours instead of days of shipping and customs 4 5.

Caution

Be careful with the ribbon cable when you reseat it, because it can be damaged during the repair 3.

What changed

Earlier, in 2014, a follow focus hand unit was restored by re-anodizing in a custom color, today, in 2022, HU3 refurbishing is done by painting rather than anodizing 2 1.

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Why do I keep losing wireless signal between my HU3 and MDR?5 threads · latest 2015

In short

Most often it's interference from other wireless gear or crowded channels near your MDR 6 7. If channel changes only help for a while, the MDR2's transceiver or receiver board can be at fault 7.

How the pros do it

Check your channels first, because the HU-3 can display which channels are in use around you 6. Use the interference reference table to see which channels conflict, and remember channel 30 is the same as channel 0 6.
On a set with several Preston systems, pair them on odd and even channel numbers instead of closely spaced ones 7. Ten Preston systems is about the limit in one area before problems show up across all units 7.
Move away from the interference source, since that resolved glitches in one report 6. Don't park multiple MDR units side by side, because that can cause glitches 6.
Look at your antennas and surroundings: swapping antennas is a recommended troubleshooting step 7. External antennas placed away from the camera body and tent structures improved range 8, and metal tents create RF shadowing 8.
Keep Bluetooth devices and Wi-Fi networks away from your receiver and iris units, since they can interfere with the control signal 8.
If channel changes only fix it temporarily, suspect the MDR2, because a faulty transceiver or receiver board was found in one case and replacing it fixed the problem 7. On an early production MDR-3 that has power lights on but no motor control, a booster board failure under manufacturer recall is the suspect 9.

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Which motor receivers and boards work with my HU3?5 threads · latest 2013

In short

Your HU3 works with an MDR2 once the G3 board is swapped for a G4 10. G4 boards only work with HU3 and single-channel MDR2 units 11.

How the pros do it

Check which board is in your MDR2, because the HU3 needs a G4 in place of the G3 10.
Use a single-channel MDR2 with G4, since G4 boards only work with HU3 and single-channel MDR2 units 11.
Upgrade the whole system together, because G4 boards are not backward-compatible and you can't mix old and new devices 12.
Plan on $450 per wireless component, covering HU3, MDR2, Radio Microforce, F/I handset and V/F receiver 12.
Don't borrow an MDR2 board for an MDR1 receiver, because the two models use different transmitter hardware 11.
If you want two MDR2 units on one HU3, Preston offers stereo firmware that synchronizes them 13.

Opinions differ here

Operators don't agree on how the HU3 behaves in the field 12. Some report intermittent interference and iris control transients even with G4 boards 12. Others report no issues, and some found the older HU2 more reliable in busy 2.4 GHz environments 12. The thread never settled whether the HU3 design or the local RF environment is to blame 12.

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How do I connect my HU3 to my camera's run/stop?5 threads · latest 2012

In short

On an Arri 416 you use the Preston F/X cable for 24 Volt Arri cameras, order number 4535 14. The sources give no general HU3 run/stop wiring for other cameras, and the only RED detail comes from an MDR2 thread 15.

How the pros do it

For a 24 Volt Arri 416, get the Preston F/X cable, order number 4535 14. With it the HU3 shows the footage counter and adjusts speed 14.
Shutter control through that HU3 link on the 416 is manual only 14.
On a RED, set the GPI trigger so the first pulse starts recording and the second pulse stops it 15. If both pulses are set the same, the stop command fails 15. That thread was about an MDR2, not an HU3 15.
Use the 4-pin GPI ports on the back of the RED 15. The side accessory port may have different GPI options, and that case was never resolved 15.
If a run/stop cable that always worked suddenly doesn't, check for camera firmware updates or changed settings 15.
If the HU3 run button clicks but the camera doesn't roll, press harder 16. The run light only comes on when the camera actually rolls 16. This was reported on HU3 software v1.11 and v1.12, and Preston offers a switch retrofit 16.

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Why won't my lenses map or calibrate properly on my HU3?4 threads · latest 2012

In short

Usually it's one of three things: the lens is non-linear and the HU3 can't map it 17, the motor mount is flexing 18, or the lens needs its own calibration 19 18.

How the pros do it

Run the six reference marks and check the spots in between 17. If the six marks are accurate but the intermediate focus positions are wrong, the lens is non-linear 17.
Know the lenses that won't map 17. The Arriflex Master Zoom can't be properly mapped on an HU3, and RED Pro Primes from 18mm to 100mm are incompatible 17.
Check the motor mounting 18. Flex in the motor mounting hardware is the most common cause of accuracy problems, and thicker rods mounted rigidly do better than thin ones 18.
Check the ring type 17. Panavision G series anamorphic primes up to 100mm need custom marked rings, while E series 135mm and 180mm work with the standard pre-marked HU3 rings 17.
Calibrate every lens on its own, even within the same focal length and brand 18. Hand-assembled lenses can differ 2-3% in physical travel, and your infinity mark has to be precise because it drives later recall accuracy 19 18.
For a RED Prime, you can partly calibrate by adjusting the close focus starting point and then manually adjusting the marks after it 17. That means guessing the final mark, and it may not be accurate closer than the adjusted close focus point 17.

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How do I fix the drag, strap ring or lanyard thread on my HU3?3 threads · latest 2014

In short

Drag is set with a 2.5mm allen wrench under a plate on the handset 20. Strap ring loosening is handled with thread locker, an inside nut and a swivel 21, and a stripped lanyard thread is repaired by reinstalling the nut as a nylon locking nut, or with epoxy, a rivnut or a temporary eyebolt 22.

How the pros do it

Drag: remove the two small Phillips screws and the plate to reach the adjustment mechanism 20. Loosen the set screws in the rubber focus knob first 20.
Insert a 2.5mm allen wrench into the top semicircular slot at the leftmost hole and rotate clockwise to add drag, one full rotation per turn 20. The factory setting is 5 turns 20.
Retighten the knob set screws to test the feel after each adjustment 20. When you have the drag you want, tighten the large center Phillips screw firmly 20. The guide only covers increasing drag 20.
Strap ring: combine a nut on the inside of the unit, thread locker and a spring washer for reliable retention 21. A stainless ball bearing swivel between the strap attachment and lanyard takes the twisting off the main bolt 21.
Stripped lanyard thread: open the unit, remove the backing nut and reinstall it as a nylon locking nut 22. Epoxy or thread-locking compound on reinstall makes it permanent, and a rivnut is a more durable option 22. As a stopgap, a quarter-inch eyebolt goes on the back where the microforce screws on 22.

Caution

Don't improvise a replacement ring, because one attempt with an improvised ring ended in equipment failure 21.

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What batteries does my HU3 use and how long do they last?3 threads · latest 2013

In short

Your HU3 uses standard Sony M-style batteries 23. Factory rating with M-Series is 6 hours per charge 24, and quality third-party M-style packs are reported at 10-16 hours depending on capacity 25.

How the pros do it

Buy genuine Sony M-style batteries, which ran $35-50 each in 2009 25. Anything under $20 is likely a low-quality alternative with poor cycle life 25.
Expect about 50 charge cycles from very cheap generic packs 25. Quality packs give 250-300 or more cycles 25.
Skip the Power2000 NP-QM51 from Japan 25. It does not work properly in the HU3 despite being marketed as compatible 25.
Choose capacity by milliamps, because higher capacity runs longer before a change 23. Those packs are also physically larger and heavier 23.
Look at third-party adapters that let you run Sony-style batteries 25. They offer better capacity and features like fuel gauges than the original equipment batteries 25.

Opinions differ here

Crews differ on capacity 23. Some prefer larger batteries for extended runtime 23, while lower capacity packs mean more frequent changes but less weight for the crew member 23.

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How do I update my HU3 firmware?2 threads · latest 2012

In short

Connect through a USB-to-serial adapter with an FTDI or Prolific chipset and the 4-pin Lemo update cable 26 27. A PC is the safer route, because the Mac updater was reported as buggy 27.

How the pros do it

Wire or check the 4-pin Lemo update cable: pin 1 is 12V power, pin 2 is ground, pin 3 is serial input, pin 4 is serial output 26.
Buy a USB-to-serial adapter with an FTDI or Prolific chipset, because Preston provides Mac drivers for those 27.
Verified working adapters are the Gearhead CA2050 and the Plugable Technologies USB to RS-232 DB9 adapter with the Prolific PL2303HX chipset 27.
On a Mac, download the USB driver files from Preston's website that match your setup 27.
If the Mac doesn't see the device, reboot it or unplug and replug the cable a few times 27.
For the most reliable update, run it from a PC or from Windows inside virtualization software like Parallels 27.

Caution

Some users ended up with corrupted firmware that only professional intervention could recover 27. Adapters with proprietary chipsets can freeze the updater mid-process, so don't gamble on a no-name cable 27.

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Sources 27

All 27 sources

What operators found

Still argued about

Often in the same threads

Follow Focus39, MDR22, FI+Z6, BFD7, Dovetail Plate3, Low Mode2

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