BMMCC map PWM to control zoom?

I'm setting up an un-manned installation that will be controlled remotely. I don't have the camera yet and I can't find the FAQ so I'm posting here.

If I use a lens like:
Panasonic LUMIX G X VARIO PZ 45-175mm F4.0-5.6 ASPH. POWER O.I.S.
Olympus M.ZUIKO ED 12-50mm f/3.5-6.3 EZ

Can I map the zoom level to a PWM input?

Are there other faster or longer motorized mtf lenses? I'm new to MFT and I'm not totally sure what keywords to search for.

[Kristian Lam]

Yes you can. Just map a PWM channel in the camera manual to one the zoom feature and you can PWM the zoom feature on the lens as long as it has a servo zoom feature.

The lens supported are:

Panasonic Lumix G X Vario PZ 14-42mm f/3.5-5.6 Power O.I.S. Lens
Panasonic Lumix G X Vario PZ 45-175mm f/4.0-5.6 Zoom OIS Lens
Olympus 12-50mm f/3.5-6.3 ED M.Zuiko EZ Micro 4/3 Lens
Olympus 14-42mm M.Zuiko f/3.5-5.6 Digital ED EZ Lens

There could be more that have not been tested.

That is good to know.

Do you have any video showing how those lenses zoom? Is it smooth, is the video usable when zooming? any differences between the lenses on this regard?

How does the Zoom function work?

- is it absolute Zooming (RC level corresponds directly to focal length), I hope the servo zooming means this,

The less preferred variables:
- Speed zooming (RC level deviated from centre defines zoom speed and direction)
- on/off zooming, i.e. not even speed control, press button up and other one down zooming?

After some more research I've found that the PWM is interpreted as an absolute zoom position. I don't know about zoom speed, that's almost certainly variable from lens to lens. Whether it is faster than the w/t switch on the lens, I don't know.

if its absolute (I assumed it was but don't have a power zoom to check) then speed is simply down to how fast whatever controlling HW being implemented changes the value (eg if you connect to a pot, how fast you turn the pot)

how 'smooth' the zooming feels though (does it feel "steppy" or seamless) will be down to the lens specifics (same with focus - I've heard the oly 12mm for example is more 'steppy' on focus adjustments than some of the other primes - the 17mm is nice and smooth feeling)

What are you using to control the SBUS? Have you tried with a direct PWM control from an Arduino or other microcontroller?

The only electrically focusing native MFT lens I have is Olympus M.ZUIKO DIGITAL 17mm 1:2.8. It focuses very nicely with the focus ring on the objective, but is very jumpy when controlled via SBUS. More jumpy to other direction.

that's weird - I've been testing with the same lens (The Oly 17mm) and it doesn't feel jumpy at all

What are you using to control the SBUS? Have you tried with a direct PWM control from an Arduino or other microcontroller?

I have both PWM and SBUS working via an arduino nano (connected through a 74HCT04N inverter for SBUS)

neither methods seemed jumpy to me when I hooked up a simple cheapo 10k pot to control the focus range via one of the analogue pins

my bad - my lens is the Oly 17mm f1.8 not the f2.8 - that may be the difference

ie this one with the clutch:

https://www.olympus.co.uk/site/en/c/len ... index.html

hard to tell on the video but I think the difference is mine takes much finer steps - yours looks like its just increment in larger jumps each time? (initially I thought it was bouncing around but that's probably just the cam shake?)

that's what I meant by this being very lens-dependant - the electronic interface on the lens itself probably dictates how fine an adjustment it can make from any external control source

I'd heard the same thing about the Oly 12mm

Kim,

Are you using the Manfrotto RC Pan Bar EX for zoom control? If the zoom control isn't absolute, do you have to reach around and set the focal length manually, or can you nudge the zoom control a bit to your desired focal length?

Sounds like no live zooms, but could you reasonably change from a two-shot to a single, fairly quickly without too much extra adjusting?

But I agree, if BM is only officially supporting four lenses, they could provide a little more documentation.

Kevin, Kim is using a SBus controller he built, not the Manfrotto RC Pan Bar EX which uses the PMW bus.
From what imhave seen with various remotes, the SBus is the most responsive on the Micro Cameras, allowing smoother lens control, and greater camera control.
Cheers

Kim,

Are you using the Manfrotto RC Pan Bar EX for zoom control? If the zoom control isn't absolute, do you have to reach around and set the focal length manually, or can you nudge the zoom control a bit to your desired focal length?

Sounds like no live zooms, but could you reasonably change from a two-shot to a single, fairly quickly without too much extra adjusting?

But I agree, if BM is only officially supporting four lenses, they could provide a little more documentation.

zoom IS absolute BTW using PWM or SBUS in that the value of the set channel is interpreted as specific level of zoom - however how that works in practice is not necessarily predictable...

As both Kim and i found with lenses the 'quality' of the adjustment seems to be very dependent on how the specific lens reacts to camera control through the electronics (as opposed to whatever normal on lens control there is - ie focusing seems to be more granular than using the lens barrel to do the same thing, even though the barrel focus rotation itself maybe be 'fly by wire')

Yes, how well a zoom or Focus by remote works on MFT lenses, is very lens dependent, and is different with the various lenses. The Panny Leica primes do well with remote focus, while the other Luminx lenses vary from lens to lens model.
Cheers

Edit: Corrected typos

Some time ago i find video with EK2-0907 Servo Tester Server Electronic Speed Controller. Probably it can control zoom as well.
I order it for experiments but it is not arrived yet. Wonder is it just plug and play controller, or is it needs some additional circuit to work?

And another interesting controller project http://www.micro-remote.org/

Some time ago i find video with EK2-0907 Servo Tester Server Electronic Speed Controller. Probably it can control zoom as well.
I order it for experiments but it is not arrived yet. Wonder is it just plug and play controller, or is it needs some additional circuit to work?

this should work without an additional controller - the servo tester itself can generate an appropriate PWM signal - you may need to wire to power as well as signal and ground of course

BTW

I've said this a few times but getting an arduino and a small breadboard plus some precut wires and a selection of cheap buttons and pots is what I'd recommend for experimenting

the smaller micro format arduinos (or cheapo clones) work fine

its pretty trivial to setup for PWM - honest

and you've got way more flexibility for future experiements

The electrical zooms I have tested with SBUS are speed control only. However the same lens works absolute when controlled via SDI (speed control is also available over SDI).

must admit this surprises me - maybe due to the zoom interface on the lenses themselves? guess I just expected it work the same as focus
I don't actually have a power zoom m43 lens to test mind you

I have had success controlling the zoom on an Olympus 14-42mm lens using a servo tester re-wired with a joystick (aka a 10k ohm linear self resetting potentiometer) in place of the potentiometer. If you want wireless control of your zoom, a standard RC remote and receiver using using pwm work as well. The key is that the control returns to center.


Available on Amazon:

Joystick - Adafruit Analog 2-axis Thumb Joystick with Select Button + Breakout Board [ADA512]

Servo Tester - YKS RC Servo Tester