DIY Wired Focus and Aperture Control

[piet meersschaut]

As I want to fly my HPX 371 on a cam crane, I was looking into various possibilities to control focus and aperture. I finally decided to build one myself, with quite satisfying result.

This video gives you an overview of the construction, the electronics and some precision tests.

https://vimeo.com/45029377

Although the servos are analog and only handle 180°, the focus precision on the Fujinon lens is quite accurate. I also tested the accuracy on DSLR's, as you can see in the video. Because of the shallower DOF, it works best with manual primes, that usually have a longer throw than AF lenses.

Total cost +/- 250 Euro's, and a weekend of intensive work Feel free to comment or ask for more details.

 

[keylight]

Nicely done. Now.... let's see some jib action! With the 371!

 

[piet meersschaut]

Thanks. Well the Jib is on order and planned for August. I'll keep you posted.

 

[Silenkiller]

I love it - this is my next plan after I motorize my slider, I want to be able to control the focus on it as well.

 

[MarcusWolschon]

Do you hear the servos running in the audio track later?
That's primarily what kept me from doing something similar yet. (And the limitation of <360° in servos)

 

[piet meersschaut]

Well indeed, they make mechanical noise. On an indoor film set, they might be disturbing, esp. if you cannot closely mike your talents. I mainly intented to use them on a jib for live situations or outdoors, and there I think you can get away with it.

 

[MarcusWolschon]

Damn.
Maybe try to hack my 14-42 Panasonic X lens instead.
It has a power-zoom and power-focus. So both are operated electronically already and they are silent.
That doesn't help with a remote operated gimbal but at least focus and zoom work.

 

[piet meersschaut]

As I got some questions about the spare parts used, let me briefly explain :

You can get almost everything direct from Servocity.com : two Hi-Tech servo's and 2 stretchers so they can handle 180 degrees and a dual servo controller.
At the local electronics store here, I bought 2 linear 5K potmeters and a 12v to 5v DC convertor. The wiring is pretty simple and well explained on the notes that come with the servo controller. hereafter a pic of the sparts used.

 

[Bryster51]

Hi Piet,

Question on what store you are shopping at for the 12v to 5v converter, if you can, please list part number or a better photo. I have need for such a device for a project and that size would be great. Depending on specs.

In appreciation.

Brian Depew

 

[piet meersschaut]

Here it is Brian :

http://www.ebay.de/itm/Spannungswan...393026134?pt=DE_Autoteile&hash=item589130f256

It's a german internet store with good reputation ;-)