Remote Focus Motor

Shawn Murphy

Shawn Murphy

Well-known member
Has anyone tried to do a DIY of one of these (the price is listed at $1,695! ouch!)



http://www.microdolly.com/focusmotor.html


focusmotor2.jpg




http://videosystems.primediabusiness.com/ar/video_shoot_tools_16/
 
I've got the makings in a box in "my" room. Not enough horus in the day, though, to have even started working on it.
 
mikkowilson said:
I built a very simple one out of scrap for a Steadicam shoot I had recently that I didn't have a proper FF available for.

Pictures: http://mikko.n3.net/photos/AntiheroWeb/

I pulled my own focus, it wasn't great, but it sure as heck did the job!
Click to expand...

Wow, that is seriously Guerrilla! But you say it did the job? Any particular motor specs we should be thinking of?


GenJerDan, any info (specs, parts, design) on the project you've been thinking of doing?

I also saw a thread that references a design by a guy named "Obin Olson", but the links are expired and Google isn't giving me anything, maybe he's still active on the boards but I'm not sure what name he goes by if he's here, but I emailed him from the dvinfo.net boards, maybe he has some good feedback on the project he worked on.

From Barry Green:

"Obin Olson has designed such a system, and there was someone else here who was working on one as well."

...in this thread: http://www.dvxuser.com/V3/showthread.php?t=18786
 
Shawn Murphy said:
Wow, that is seriously Guerrilla! But you say it did the job? Any particular motor specs we should be thinking of?
Click to expand...

Meh, that is an old tape drive motor from an old Casette tape player if I recall correctly. Stuff specks, I grabed it, along with the gears (which miraculourly have the same pitch as a Canon ENG lens), slapped on a 9v battery to the leads, then used my massive choice from about 4 gears to select the 2 that I could fit together and give an acceptable ratio/tourque. ONE (yes, one) screw to hold the whole assembly together and a bit of double sided tape and a zip tie to hold it to the lens.

Thoguh I was shooting with a 2/3" camera, I light brightly and shot wide (as it was Steadicam and a small space anyway) so i had a pretty tight Iris and a deep DoF - which was fine as it was a [rock] music video. The FF only had a direction switch and a 'fast' and 'slow' button. - It woudl be no good for precise work, but it allowed me to do simple shifts during big moves to keep me well inside that "good enough" area of the deep DoF.

A short clip from the shoot is here: http://mikko.n3.net/videos/AntiheroS...offWebclip.wmv (1min 3MB) - if you look carefully, you can see the light tape on the end of the lens rotating in the 'behind the scenes' shot.

- Mikko
 
Well, I found some more info on the stuff Obin was doing, posted over at dvinfo, apparently his finshied product is/was around $1200


Lens-Slingers_follow-focus-.jpg
 
Here's what Obin had to say:

"Well Well, people really do drag things from the past!! LOL yes I made that thing, yes it worked well for steadycam, but no I never sold a single one, and to be honest it's a bit noisy...I think you need special motors that don't make sound to do it the way it should be done..I never could find some.. so ...I have a CNC mill that I cut the gears with, that was not a problem at all, and the radio controller works great....if you can find a motor/servo that does NOT make sound you will have a winning system...

Sorry I can't be more help, I wish you lots of luck and if you need any help let me know."
 
Yeah. This way...assuming a whole lot...it'll work with whatever I have. Even an adapter (35mm or otherwise).

I'm mostly interested in being able to program it, though. Maybe put together a whole motion-control thing.

In my copious free time. :grin:
 
GenJerDan said:
...I'm mostly interested in being able to program it, though. Maybe put together a whole motion-control thing...

:grin:
Click to expand...


Intriguingly elaborate! That explains the other parts, I kinda looked at them and went, "huh?" :shocked:

Now what to do about freeing up some of that "copious" free time!


'Motion Mind':

MM1.jpg


The Motion Mind DC Motor Controller is a motion control product capable of controlling one brushed DC motor. A variety of control methods are supported including open loop and closed loop control. Open loop control methods do not require feedback from an encoder and can operate with serial data input, button presses, analog control signals (0-5V), and pulse control from a hobby R/C type control signal (1-2ms pulses, approximately every 20ms). Closed control requires either a quadrature encoder (2 channel with or without Index channel) or an analog feedback signal (0-5V). When operating in closed loop modes position and/or velocity control are possible. Some limit switch functionality is supported through negative and positive limit switch inputs. The state of the index input from a three-channel encoder can be monitored and the approximate position of the last index pulse present is available.

In addition to a variety of control techniques the Motion Mind module has numerous communication settings available to the user. A high-speed binary communication protocol is implemented. The binary communication protocol may be replaced with a simpler ASCII command set through an external jumper. The ASCII protocol ensures ease of programming with simple terminal programs. An external jumper determines the baud rate (19.2KBPS or 9.6KBPS). Electrically the Motion Mind can communicate at RS232 levels
through an on-board translator IC, or through a TTL serial interface with an open-collector output that allows multiple modules to share the same data bus.

The board measures 2.4” wide x 3.6” long x 0.6” tall. The Module is powered directly off of the motor voltage and may provide 200mA of regulated 5VDC voltage to other off board devices.



'ENC300':

ENC300.jpg



This encoder kit can turn the Easy Roller Robot Wheel Kit (EZR) into a "dead-reckoning" robot drive system. Implementing complex position control algorithms is simplified with this encoder.
 
Yeah. Ain't it pretty? And not expensive, considering.

The hardest part will be mounting it to the camera. I think I'll be building a combo rod system/mount. Might as well make one unit, right?

Assuming I can find a machine shop around here that will bore the holes without charging me out the ying-yang
 
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