BFD

186 threads in the archive

Based on 187 threads · 50 cited

AI draft, not reviewedDraft, written by AI from the archive, every statement linked to its source — not yet reviewed.

The BFD is a single-channel focus device that costs less than a Preston FI+Z, which handles focus, iris and zoom on three servo channels 26. You can power it from a P-tap on the battery cradle or a 12V Lemo output on the sled 1 2, and you need a motor with a potentiometer, so Heden M26P and Palomar M-One are the safe picks 12 13. If it twitches or drops signal, check RF interference, then power, then a worn potentiometer in the motor 17 18 19.

The questions 9

How do I power my BFD receiver from my camera or sled?16 threads · latest 2014

In short

Power the BFD from a P-tap on the battery cradle 1 or from a 12V Lemo output on the sled 2.

How the pros do it

Run a dedicated P-tap to BFD power cable from the battery cradle 1. Camera aux ports are built for small accessories and lack the amperage for focus motors 1.
On a sled, use a 12V Lemo output and share one circuit with the monitor, level and other accessories 2. On a three-battery sled, dedicate one battery to accessories 2.
With only one 2-pin Lemo output, split it with a parallel-wired splitter, one male 2-pin to two female 2-pin 3. Lemo makes splitters for the Flyer and FlyerLE, and you can also run a junction box with P-tap, XLR or Tiffen outputs 4.
If you use a video transmitter, test it with the receiver before the shoot 3. RF can leak back through the power cable and block the follow focus signal 3.
On a Sony F5/55, parallel two 1.8A Hirose circuits or use a D-Tap power adapter instead of a single Hirose 5. On an Alexa, the RS port gives 2 amps total, so use an external D-tap source or a Y-split cable to external batteries 6.
On a Flyer with one power connection, power the BFD on before the camera so the startup surge doesn't shut the camera down 7. Better still, run the camera from its own handgrip batteries and keep the follow focus on the rig 7.

Caution

In 24V mode on a cinema sled, don't power video devices from the auxiliary D-tap, because their BNC shields can short the auxiliary battery negative to the camera battery positive and damage equipment 10. Check the power requirements of any device before you plug it into a stabilizer output 11.

Opinions differ here

The F5/55 Hirose is contested 5. One side says the 1.8A Hirose can run a BFD with FMG-6 motors, which typically draw under 1.5 amps, with the BFD at 3 amps only in worst-case conditions 5. The other side reports that draw during lens stops can momentarily exceed the rating and trip the fuse, and that the manufacturer's safety-margin claim was not independently verified 5.

What changed

Earlier, in 2006 and 2007, operators ran follow focus gear from the camera's AB tap, D-Tap or Hirose outputs 8 9, while today, in 2009 and 2014, the advice is a P-tap off the battery cradle, a D-Tap adapter or paralleled Hirose circuits 1 5.

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Which motors are compatible with my BFD system?11 threads · latest 2018

In short

Heden M26P and Palomar M-One are the safe picks for a BFD 12. The motor needs a potentiometer for position feedback, so T-only Heden motors are out 13.

How the pros do it

P motors with a potentiometer connect to a BFD, T motors with only a tachometer can't be used for focus 13. PT motors work too but need a different cable connector 13.
The M26P uses 5 pins and the PT variants use 7 pins 13.
Heden M26P runs on the BFD without modification 12. M28VP and M21VP need a servo loop gain adjustment with four resistor changes 12.
The M-One is built to work with Bartech systems and has enough torque for tight lenses 14. On older BFD units you may have to readjust the BFD for its extra power output 14.
Cinema Products and SPF FMG-6 motors are listed as less desirable for the BFD 12. Stanton motors need a BFD modification, which runs about $100 for a hi/lo switch and about $125 for a custom cable 15.
For digital motors like Preston, a digital PLC receiver is required to connect a Bartech handset 16. Most Bartech handsets work with both analog and digital receivers without modification 16.

Caution

Stanton right-angle motors need a BFD modification to prevent motor damage 12.

Opinions differ here

Stanton motors split opinion 12. One user reports running a Stanton motor successfully 12. Others point to the noise and to the BFD modification that may limit backup motor options 12.

What changed

Earlier, in 2004, Heden M26P motors were reported as reliable over long use 14, today, in 2016, Heden no longer repairs analog motors, so sourcing and service matter more 15.

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Why does my BFD motor twitch or lose signal?12 threads · latest 2013

In short

Twitching and signal loss mostly come from RF interference, weak power, or a worn potentiometer in the motor 17 18 19. Check them in that order 17 18 19.

How the pros do it

Keep the Modulus off the BFD receiver and below channel 50, because a Modulus 3000 placed against a Bartech receiver causes interference on any channel 20. Never stack a Modulus on top of the receiver 21.
Move your video link off 900 MHz, because a 900 MHz transmitter near the BFD receiver can overload it and kill reception 22. A 2.4 or 2.5 GHz video system is the recommended fix 22.
Fight the RF itself by changing the wireless channel and isolating the motor cables from other cables, since motor cables can act as antennas 17. Expect it to be worse on sound stages, where signals bounce off walls 17.
Check your power, because low battery voltage can make a BFD motor oscillate 23. An underpowered AC supply also causes twitching, especially with a right-angle motor cable, and a battery source eliminates it 18.
Look at the hardware: loose connector pins in the cable housing can leave the motor knob dead, and tapping the motor or reseating the cable can bring it back 18. A partly broken receiver antenna with damaged threads can also upset motor control 17.
Check firmware and internals: outdated firmware handles RF poorly and gives vibration followed by handset dropout, so make sure the CPU chip and RF module are fully seated 24. A worn potentiometer in the M-One motor causes random vibration, and replacing it is the permanent fix 19.

Caution

Plugging a power connector into the data input socket instead of the correct port can blow an internal fuse and stop the receiver working 21.

Opinions differ here

Some reported that 900 MHz senders and sound-department wireless mics made motors stutter 23. Others ran a BFD alongside several wireless mics and transmitters with no problems 23. One source says a 900 MHz video system can coexist with careful placement and channel choice, but calls that unreliable 22.

What changed

Earlier, in 2004, operators blamed low battery voltage and 900 MHz senders for erratic BFD motors 23, today, in 2012 and 2013, the sources point to outdated firmware and a worn motor potentiometer 24 19.

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Should I choose BFD or Preston and other follow focus systems?10 threads · latest 2016

In short

Both are technically reliable, so the choice comes down to channels, shot demands and who hires you 25. The BFD is a single-channel focus device at lower cost, while the Preston FI+Z handles focus, iris and zoom on three servo channels 26.

How the pros do it

Count the channels you need 26. Preston FI+Z gives you focus, iris and zoom, and the BFD is single-channel focus only 26.
Check the shot demands 26. Preston's 16-bit resolution against Bartech's 12-bit is cited as an advantage for anamorphic at night or precise repeatable moves 26.
Weigh the durability and service 27. Bartech units from 1997 still work, and spare parts reach remote locations within 48 hours 27.
Think about who you work with 25. Some assistants see Preston as the standard and doubt Bartech, but some skeptics became advocates after using it 25.
Mix them if you want 28. A Bartech can back up a Preston that fails on set, and the BarTech Digital Receiver can drive Preston motors 28 29.

Opinions differ here

Operators split on whether Preston's edge matters 26 25. One side says Preston's higher resolution helps on anamorphic night work and repeatable moves, and that the US market expects it 26. The other side says Bartech matches it for basic focus pulling at roughly half the rental rate in England 26.

What changed

Earlier, in 2007, some assistant camera operators were skeptical of Bartech and preferred Preston as the standard 25, today, in 2016, Bartech is more widely known among focus pullers and first assistants and easy to operate without extra training 27.

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How do I mount my BFD receiver on my sled or rig?9 threads · latest 2016

In short

Use a fixed bracket that fits your sled's hole pattern, not loose adhesive 30. On a Master Series rig, that means a dual BFD bracket drilled into the flipped nose section's metal lid 31.

How the pros do it

On a Master Series top stage, unscrew the four screws on the inside rear and remove the nose section 31. Flip it upside-down so the metal lid is on the bottom, then drill through the lid for a dual BFD receiver bracket 31.
On a PRO sled, a small dovetail plate slides into the receiver slot and holds the bracket underneath 32. You can buy that plate directly from PRO 32.
Check hole spacing before you drill or buy 30. Arri-compatible brackets use 60mm and 100mm rod spacing, Glidecam plates have 52mm and PRO plates have about 49mm 30.
If the spacing doesn't match, add a mounting plate or extension to the end of the dovetail plate and drill your own holes 30. A hot shoe mount on the camera handle is another option 30.
On a Tiffen rig, some operators had the front nose modified by a service provider to accept standardized mounting brackets instead of relying on adhesive 33.
If you run analog BFD and digital BDR together, a 2011 prototype blue bracket held up to two BFD receivers, with a second bracket screwed on for one or two digital receivers 34. It was only a prototype and not in production at that point 34.

Caution

If you use Velcro on a Tiffen rig, the setup depends on cable support for safety during operation 33.

Opinions differ here

Operators don't agree on Velcro 35 30. One thread offers 3M Dual Lock or velcro strips under the receiver as a removable mount that spares the aluminum bracket threads 35. Another calls Velcro convenient but less reliable than fixed brackets for professional focus work 30. A 2011 thread says industrial Velcro works but depends on cable support and lacks the elegance of solid mounting 33.

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How do I calibrate my BFD and handle marking rings?7 threads · latest 2014

In short

Calibrate from the infinity mark to the closest focus mark, not to the end stops, with the lens near mid-travel when the motor engages 36. Use hard plastic marking rings instead of fabric strips, and remark them for each lens set 37 38.

How the pros do it

Put the lens at about the middle of its travel when you first engage the motor 36. That spreads the resolution evenly 36.
Calibrate from the infinity mark to the closest focus mark, not to the physical end stops 36. Motor torque can twist the bars at the end stops, so infinity-to-close marks give more consistent results 36.
Swap the fabric strip for a hard plastic ring if you can, because the fabric strips supplied with BFD units can slide and need fastening 38. A hard ring fits with the existing screw fastener and takes standard 19mm tape 38.
Match the ring to your handwheel: pre-May 2002 BFD knobs are about 2.917 inch, post-May 2002 about 2.940 inch 38.
Mark the rings on camera prep day and store them in the lens cases 37. Each lens has its own mechanical character, so a ring marked for one lens won't match the same model from another batch or serial number 37.
Clean a used ring with alcohol and remark it for the next lens set 37. Note on the ring which lens position you used during calibration, so you can repeat it when you swap back to the same lenses 36.

What changed

Earlier in 2005 operators marked and reused strips between the same lenses 36, today (2009-2014) they use hard plastic rings, and for older Bartech knobs also Delrin, 3D-printed or factory aluminum discs 37 38 39.

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How do I build or pin out BFD cables for RED and Sony?6 threads · latest 2018

In short

For RED, wire a LEMO-to-LEMO contact-closure cable and set the BFD to MOM mode 40 41. For the Sony F55, the sources give the Hirose 4-pin pinout and say a simple cable can trigger record 42.

How the pros do it

Build the RED end with a LEMO FGG.0B.304.CLAD42 and put the signal on pins 1 and 2 41. It goes into the upper 4-pin LEMO on the back of the camera 40.
Build the BFD end with a LEMO FFA.0S.304.CLAC42 and put the signal on pins 2 and 4 41. Which wire goes to which pin doesn't matter, because it is a polarity-independent relay contact closure 41.
Set the BFD unit to MOM (momentary) mode 40. The RED records when pin 1 (ground) is momentarily shorted to pin 2 (GPI), on firmware build 10 and later 40.
For the Sony F55, the Hirose 4-pin is pin 1 unregulated ground, pin 2 record tally, pin 3 record trigger (active low) and pin 4 unregulated +12V 42.
A simple F55 cable with no microprocessor can trigger record and is compatible with Preston systems 42. Sony record start/stop varies by firmware, so some units won't enable it whatever cable you build 42.
For BFD power cables, BFD receivers and Teradek units use the same 2-pin connector with opposite polarity 43. Check with a BFD handset with its 9V battery removed before you plug in 43.

Caution

Don't plug or unplug the Hirose connector on a powered F55, because it risks damaging the circuit board and the SDI output drivers 42. Panasonic ENG cameras use the same Hirose connector with different pinouts, and a BFD power cable with the wrong polarity damages equipment 42 43.

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What's an affordable BFD setup I can expand later?6 threads · latest 2014

In short

Start with a Bartech BFD and M-One motor, which operators call reliable and cost-effective 44. The BFD lets you begin with one or two channels and add more as budget allows 45.

How the pros do it

Buy the Bartech BFD with M-One motors as your base 44. It holds up well against more expensive systems 44.
Start with one or two focus channels and add channels as your budget and needs grow 45.
Budget about $4500 for a BFD with a Palomar M1 motor, fully assembled with cables and backup parts 46. That was the 2006 figure, so treat it as an estimate 46.
Carry redundant cables for sled-to-focus power, motor and camera control 46.
If you go digital, the Digital BFD expands to two channels with separate transmitter and receiver units 47. A two-channel receiver had not been released at the time of that thread, so check availability first 47.
Plan on calibrating the BFD by hand, since it is not automatic like the Chroziel DigiFox 44. Bartech repairs have a fast turnaround, even when shipping internationally 44.

What changed

Earlier, in 2004, the BFD let you add focus channels step by step 45, while today, in 2014, the Digital BFD expands to two channels through separate transmitter and receiver units 47.

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Will my BFD still work in cold weather?4 threads · latest 2010

In short

Not guaranteed. One BFD failed to power on after five hours at minus 7°C and recovered at room temperature 48, while another operator reported it working in a Russian winter 48.

How the pros do it

One unit stored in a vehicle at minus 7°C for about five hours would not power on, then worked normally back at room temperature 48.
Bartech traced freezing-temperature failures to a temperature-sensitive voltage regulator component and resolved it 49.
It ran reliably in the same minus 7°C conditions where the BFD would not power on 48.
Below minus 10°C, expect slow wireless focus motors, because the cold stiffens the lens focus mechanism more than it affects the motor 50. Self-adhesive heat packs on the lens give several hours of light, constant heat 50.
In extreme cold, try a higher-voltage power supply or NiCa batteries 50. Watch for motor shutdown, since some systems cut out when a cold, stiff lens demands too much power 50.

Caution

Heating a lens between takes can cause condensation and ice formation, so manage it carefully 50.

Opinions differ here

One BFD would not power on after about five hours at minus 7°C 48, and Bartech identified a component that failed below freezing 49. Another user reported successful BFD operation in Russian winter conditions 48.

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Sources 50

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What operators found

Still argued about

Often in the same threads

FI+Z14, Follow Focus110, Base Plate4, Modulus12, Zephyr8, Top Stage12, HU37, Master Series4, MDR13, Low Mode10, Dovetail Plate8, G-705

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