Introduction: Zocus - Wireless Zoom & Focus for Your DSLR Camera

About: Black sheep engineer, Chartered, and very silly. Currently living in the UK. I have been fortunate to have lived, studied and worked in Hong Kong, Norway and California. I believe physical models help people…

Zocus allows you to wirelessly control the Zoom and Focus of your DSLR Camera, via the Bluetooth enabled ZocusApp, on iPad or iPhone (Android coming soon).

It was originally developed for James Dunn, who is passionate about photography, but who also had a condition called Epidermolysis Bullosa, which made his skin to be very sensitive to even slight pressure - causing him pain and frustration when trying to operate fiddly camera buttons or scroll/jog-wheels. James wanted to master this art, and feels it is not enough to take pictures on his smartphone - he wanted full creative control of a professional DSLR camera, to frame and focus the world as he sees it.

Although there is a staggering amount of Follow-Focus gear out there, it often struggled to fulfil James' brief:

  • Both Focus and Zoom must be controlled button/dial-free.
  • Turning the Zoom ring on a lens is often far more difficult, (high torque) than only the Focus ring.
  • Many Follow-Focus rigs are controlled via a large wheel/dial, which James couldn't operate.
  • Many Follow-Focus rigs are for professionals only, and so are costly (£thousands).
  • Very few (if any) have free Apps which work with tablets/smartphones.

The Zocus' Electronics cost less than £90, which means if you have access to a basic Soldering & Electronics Equipment - and 3D Printer (local maker spaces or hobby clubs often have them) it is quite cheap to build for yourself or someone who needs one! However, if you do need to order 3D Printed Parts, this can be done from companies like Shapeways, for around £110, bringing the total to around £200: This reduction is cost may also be attractive to enthusiasts and film-makers who are working on a tight budget.

This first version of Zocus is featured on the BBC2 Documentary - Big Life Fix. It has been designed and documented here to allow others to improve on this idea through Open Source sharing of the both the 3D Printable Hardware, and Software.

Step 1: SECTION A: Select the CAD for Your Camera Lens

The original CAD for this project was designed around a Canon 600D (aka Rebel T3i in the US), with a Tamron 28-300mm Lens. The Camera is a solid entry-level DSLR and is widely available and the Lens is a great 'all-rounder', with the 28mm-300mm range being a good wide angle for landscapes and portraiture. It also has a reasonable zoom and image stabilisation for sightseeing, is reasonable for indoor photography and has Macro for close-ups.

As one might expect, it's hard to design CAD for every possible combination of Lens and Camera. However, the Zocus will work with many similar cameras and lenses out there - but it's worth using the Selection Flow-Chart to see what CAD you'll probably need. (You may not even have to modify the CAD at all!).

Depending on which of the 3 Options you were guided to, please skip to those sections by scrolling down...

Step 2: Option 1: Download Zocus V1.0 CAD Files - Ready for 3D Printing

Download the whole .zip file: It contains both .stl files (for 3D Printing) and .sldprt (files for editing).

The Essential Parts for Zoom + Focus control are:

  • 2x Geared Focus Rings*
  • 2x Servo Motor Gears*
  • 4x Servo Mounts*
  • 1x Control Box
  • 1x Control Box Lid

*You can of course just make a Zoom or Focus only, using half these numbers.

The Optional Parts are:

  • 2x Battery Holder (you may prefer to power from a different source)
  • Cable Clips (you might just use tape or zip-ties)

Ready to Print? Jump to Section B -->

Step 3: Option 2: Download Zocus Adjustable Rings CAD Files - Ready for 3D Printing

Download the whole .zip file: It contains both .stl files (for 3D Printing) and .sldprt (files for editing).

This is similar to Option 1, but instead of the usual Geared Rings, there is a set of 4 Adjustable Sized Rings.

You may select the ones you need, or if unsure, print them all.

Main Segment 0 affords 63-66mm diameter lens rings.

+ Segment 1 afford 70-79mm diameter lens rings.

+ Segment 2 afford 79-83 mm diameter lens rings.

+ Segment 3 afford 82-88 mm diameter lens rings.

(You can also combine these, e.g. 0+2+3 affords 95-99mm, though if you're driving e.g. a huge 120mm diameter lens ring, chances are these servos motors will struggle).

If you wish to edit them further, open the .sldprt files, and edit them in SolidWorks.

Ready to Print? Jump to Section B -->

Step 4: Option 3: Edit the CAD Yourself

SolidWorks is professional CAD software. It usually costs a fair bit of money, by hobbyist standards. However, most students get it for free/very low price. However, if this does not apply to you and you only really need it for this project, you'll be pleased to know you can get a short free trial! Hurrah!

If you'd rather start from scratch, create your own add-ons, you can also try Fusion360 and OnShape.


The basic forms of the gears are shown here. They were created in SolidWorks, using the 'ToolBox' function. Gear Design tends to rather 'throws you in the deep end' of CAD and Engineering, with a lot of unfamiliar terms. However, if you are not a Mechanical Engineer, rest assured you do not need to understand everything to still get what you want out of it!

Take a quick look at this tutorial. It is quite simple to just 'muddle-through' and adjust the parameters and it updates 'live', so you can see the part changing in real time! From the drop-down menus, you only need to vary two things between each of the gears:

Number of Teeth: Large Gear (Lens) = 120, Small Gear (Servo) = 36

Nominal Shaft Diameter (the hole in the middle): Large Gear = 80, Small Gear = 22

The other selections/parameters just keep the same (or at least the same between both gears):
Face Width (width of the gear) = 10mm (you can make this smaller/larger if you like), Module = 0.7, Pressure Angle = 20, Hub Style = None, Keyway = None.

Finally, "Save As..." the individual parts, and then take them into your main assembly do that you can build upon them... If you're familiar with SolidWorks, you'll be able to model the nut and bolt features quite comfortably, I suspect. If not, and you want to do better than YouTube videos, then there are excellent tutorials on CAD Junkie.

If you don't have access to CAD - try your local hackspace or if you are wanting to use free software, I would suggest On-Shape or 123D - there you can either import the SolidWorks files and modify them or create them from scratch. Arguably this takes longer, as you'd have to model the gear teeth yourself, but it is all free.


Right, so you're really, really, serious about designing something. Great to hear!

The good news is that you have a fully constrained sketch to work from. I can't promise that it will cope with every possible adjustment and update flawlessly (when does CAD ever do this??), but if you're working on the basic 15mm camera rails, and just needs a different position, this will cope with most tweaks.

As with all things Open Source - if you do a better job - upload and share!

Ready to Print? Jump to Section B -->

Step 5: SECTION B: 3D Print Your Parts

3D Printing these parts will cost very little (about £3 or $4) in raw materials, if you have a 3D Printer.

If you don't have one, no problem, you have 2 options:

A. Visit a local Makers Space, Hack Space, Community Workshop (only a google away). They will invariably have someone there who'll be enthusiastic about 3D Printers and will probably be keen to help you. (Though biscuits and/or booze will usually improve your chances). They will also have most of the electronics tools you'll need and probably some nuts, bolts, etc. you can get for this project.

B. If you'd rather just order the parts online. You might want to take a look at (shown), or any other online service. Some 3D Printing services also have stores in town - and if you get stuck on the CAD, many offer services to help fix/modify CAD - just bring the .sltprt files for them to take a look at.

Step 6: SECTION C: Parts Assembly


Small Philips and Flat-Head Screwdrivers

Hex Keys (ideally Ball-End) (Amazon)

Pin Vice (Amazon)

Drill Bits (1.2mm to widen holes if needed) (Amazon)


15mm DSLR/Camera Rails (Neewer on Amazon)*

M3 Nut & Bolt Assortment (Amazon). NB: Specific Sizes required: (8x12mm; 8x15mm; 2x20mm)

2x Servo Motor (Wide Angle 300 degrees). I used HDKJ D3015 (Amazon)**


2x Lens Rings; 2x Servo Gears; 4x Servo Mounts; 4x Wire Clips.

* I'm not getting paid to say this - but I think Neewer is a fantastic brand for entry-level photography gear. This 15mm Rail is perfect for the Zocus and is compatible with other more expensive gear out there.
** This is a special type of Servo Motor. Most are 180 degrees. This is 300 degrees - which is great for lenses with wide turning angles for zoom. The torque is also pretty high, which is important for zoom control. Specification show.

Step 7: Servo Assembly

Part 1: Servo Gear Fitting.

  1. Remove the central screw from the Servo.
  2. Use the Pin Vice and 1.2mm Drill Bit to widen any of the holes, if your 3D print is a bit tight fitting.
  3. Press in the horn (wheel) into the 3D printed gear.*
  4. Check the assembly fits and can rotate freely.

* You can also apply Super-Glue/Epoxy if you want to ensure that the horn is well fixed to the 3D Print.

[Remove Gear & Horn Assembly]

Part 2: Servo Mounts.

  1. Press Nut in the hexagonal hole of the Mount.
  2. The fit is tight, press firmly.
    (If still too tight - lightly hold the nut with a Soldering Iron tip and allow it to 'melt into place'.)
  3. Screw the small Bolt into place.
  4. Do the same for all clamps. Also set the other 4 Nuts in place in position as shown.
  5. Feed the 3 wires through the assembly.
  6. Press Servo into place.
  7. Using the medium sized bolts, clamp the two Mounts together.
  8. Screw the Gear & Horn assembly back on.

[Repeat for the second one - but in reverse, as shown]

Note: The Zoom is the closest/'Right' Mount and the Focus is the farthest/'Left' Mount, for the Tamron Lens.

Step 8: Mount on Rails

These rails are 'universal' and can be used an many different photo/film equipment.

  1. First of all - add the (optional) wire clips on either rail.
    For the Tamron Lens:
  2. Press the 'Zoom' Mount on first.
  3. Press the 'Focus' Mount on second.
  4. Clip the wires in place.
  5. Tighten up Bolts.

Step 9: Fitting the Lens Rings

WARNING: Do not over-tighten the Bolts/Nuts - you only need there to be *just enough* grip to hold the rings on the Lens. Any more than necessary could potentially crush/compress the lens.

  1. Slide Rings on the Lens at the Focus and Zoom locations.
  2. Flip-over and check that the Ring is nicely aligned all the way round.
  3. Gently tighten up.

Step 10: Aligning Gears

This bit does take a bit of fiddling around to get right. Here are the main steps, though you may need to go back and adjust one or two to get the perfect alignment.

  1. Unscrew the Blue Clamp.
  2. 'Swing' out the Q-R Mount.
  3. Screw (finger-tight) to the Camera.
  4. Check docking.
    [Move the Lens Rings if needed, by loosening the Bolt a little]
  5. Loosen the hight-clamp. Lower the camera/lens so that the gears 'mesh' together.
  6. Remove the camera again and tighten the Q-R Mount fully with a screwdriver.
  7. Check meshing from both sides.
  8. (Tighten the Blue Clamps and bolts again).





  • BluTack (Yes - this is actually going to change your soldering game). Get Some!
  • With the exception of the Blend Micro, your local Hackspace will have most of these components, so you could save some time, money and effort just checking first.

* Soldering has nasty fumes. I use a BOFA V200 Extraction unit to be safe, but if you don't have a filter do try to work in a very well ventilated area if you don't have fume extraction.

** You can solder directly to the PCB rather than using the Header Sockets. Pros are that you save money and space, Cons are that you will have a bad time removing the Blend Micro if you want to make changes, or use it in another project, etc. Your call.

Step 12: Circuit Diagram

What's going on?

  • The Blend Micro (BM) is a transmitter and receiver of the Bluetooth info.
  • According to the commands of the App sliders, the BM is sending pulses out through pins 10 and 11 to trigger the servo motor. It's called a 'signal' pulse.
  • Ordinarily, if the servos were very small you could just use the BM signal to run the Servo. However, as these servos are more powerful, they need 6V and at a higher current (>200mA) than the BM can cope with.
  • So we use a Transistor to pulse/switch a higher power circuit to generate a higher power signal, with the same control pattern as the BM's output (called PWM).
  • The Diodes are a cautionary measure to keep any residual current from flowing backwards in the circuit.
  • The Green Signal Circuit is for Focus (think Green AutoFocus Square), the Yellow if for Zoom.

Transferring this to your Prototype Board can be quiet challenging. My suggestion would be to follow the sequence as shown in the following steps. If you are unsure of if you have the circuit right - check with a Multimeter. If you have never soldered before, this is a simple enough circuit to experiment with, and I show a few tips along the way.

If you're a Pro, just skip on and get it done how you like it!

(Any tips on what you'd do better are most welcome! This is what Open Source is all about...)

Step 13: Prepare the Blend Micro

Score & Snap Female Pin Sockets:

  1. Score
  2. Snap
  3. Trim off excess
  4. Install on Header Pins of Blend Micro

Step 14: Mount the Socket to the Protoboard

Take care with the orientation of the board, to ensure a good fit in the housing box.

  1. Position the Blend Micro assembly near the middle of the Protoboard
  2. Flip upside-down. Hold steady with BluTack
  3. Solder the 'end points' only at this stage (in case you need to reposition later)

Step 15: Solder the Servo Header Pins

This allows you to position the legs carefully - and then get a stronger joint from the extra soldering.
(If you just solder from the underside first time, your legs will most likely not be straight.)

  1. Take the Right-Angle Header Pins and position as shown - using Blutack. Solder the 'middle' leg of the 3 - from the top-side
  2. Flip over and solder the 'outer' legs

Step 16: Mounting the Headphone Jack (Power Socket)

Why use a Headphone Socket for power-supply?
Well, when I started this project, I didn't know how long I needed the wires to be, as much of the design was done remotely. The great thing about 3.5mm cables is that they are cheap and come in various lengths and a have connectors already on them! You can of course use other connectors, but I found this a pleasingly efficient and adaptable system for low-voltage/current systems.

  1. Bend the legs of the Jack terminals as shown, in preparation.
  2. Position the 4 header pin section as shown.
  3. Solder from the underside. (The blutack will ensure the pins are straight).
  4. Align the 'socket' with the edge of the board as shown. (Note - not the panel mount ring!)
  5. Solder the terminals of the Jack to the Header Pins.

As you can see on the last picture, Blutack can be used to help position the other components, while soldering underneath. Not only do you avoid burning your fingers, but you also get a more accurate layout.

Step 17: Adding Jumper Wires

Small connections can be made by 'bridging' solder joints, but for longer connections (or ones which cross over another path) using 'jumper' wires can be the most efficient way to wire up.

  1. Strip the ends of the wires and add a small bit of solder to the ends. This is called 'Tinning'. It's a bit of a Pro Tip - and also stops the strands of wire from splaying as you push them through the hole.
  2. Wire up the signal wires from pins 10 and 11 (these are written under the Blend Micro if you are unsure).
  3. The Blend Micro can be powered via the "VIN" (#3 Left) Pin from 3.3-12V, so we can power the Servo with 6V, the Blend Micro will be fine with this.
  4. Similarly, the ground needs to be common, so this also goes to the Jack.

Step 18: Making Solder Tracks

  1. So you might want to use the 'mirrored' circuit diagram here. The trick is to take it one component at a time. I've set out the board in a way which is reasonably efficient to find solder tracks to make the circuit. I thought I'd also include tips on how to create tracks to 'bridge' between components.
  2. This is the end result. Just to you get the idea.
  3. Create small dots of solder in each point of the Prototype Board. Allow them to cool.
  4. Add a lot of solder to the tip of the soldering iron then place it on one of the dots, and drag it to towards the next one. It take a bit of practice, but it starts to make sense when you try it.
  5. Add more solder to the iron and drag a new line.
  6. Note that I've often bent the wires of the components in the opposite direction I want to run the track, so I have more space to work (and correct).
  7. Go back over the tracks with more solder if they are a bit 'thin'.
  8. Trim the legs of the components with side-cutters. (Use Safety Goggles as the component legs can fly!)

If you make a mistake, you might want to try this video on how to use a solider pump to remove solder.

Step 19: Final Checks With a Multimeter

I suggest using a MultiMeter to check that all your circuit connections 'go' to where they are supposed to. Sounds obvious, but far better than blowing up a Blend Micro (but that's why you didn't directly solder it to the Protoboard, right!?).

You are now all set for Powering Up!

Step 20: SECTION E: Power-Up (Battery or Mains Power Adapter)

James's Zocus is powered from a Wheelchair Battery. (We might come back to that with another Instructable).
However, you may also want to wire up power from smaller batteries or even mains electricity*.


You will need:

Battery Pack (4x AA) (Amazon)
Heat-Shrink (Amazon)
3.5mm Panel Mount Audio Socket (Amazon)

Drill (with bit to fit socket hole)
Scalpel (with a straight or hooked blade)
Lighter (Not shown)

3D Printed Parts


  1. Cut out any 'ribbing' to allow the 3.5mm Socket to fit.
  2. Drill a hole for the Socket to fit through.
  3. Check fit.
  4. Cut wires from Battery Pack to size.
    (N.B. You will want to check that you have the same wiring as on the PCB)
  5. Solder to Socket. (With Heat-Shrink in place before).
  6. Use a lighter/blowtorch to shrink Heat-Strink.
  7. Add Socket Nut. Add Batteries.
  8. Slide over the 3D Printed Parts.
  9. Slide on to rails. Wire-up with 3.5mm Audio Cable (Amazon).
  10. Switch on. The Gears should


  1. Cut the end of a connector from a 6V DC Power Adapter (Amazon)
  2. Prepare the wiring, checking the polarity with a Multimeter.
  3. Check wiring alongside the PCB Socket.
  4. Apply a larger tube of Heat-Shrink over the entire assembly.

*Always be careful with Mains Electricity. If unsure, check with a professional.

Step 21: SECTION F: Arduino Code for Blend Micro

I should say upfront that, I agree that the guide looks initially quiet intimidating for setting up the Blend Micro, but (arguably like this guide) its granularity should see you right if you follow each step.

Red Bear Blend Micro Setup:

Once you have that, you can open the Arduino Code for Zocus, (open the .ino file, or cut and paste the .rtf text) and upload it onto the Blend Micro. Once you have done this once, that's all you need to do. You can now plug-in or solder in your Blend Micro back to the PCB.

Some useful things to know are:

  • If the Pin configuration for the Zoom and the Focus is the wrong way around, for how you'd like to mount it to your system, you can easily change the numbers around in the code, rather than rewiring.
  • You can edit the sweep of the servo motors (if you have one greater than 300 degrees).

Step 22: SECTION G: Install the BlueTooth Unit

The housing can be edited to suit how you'd like to mount it to your camera. The main thing is to keep it safe from water and knocks.

  1. Push the 3.5mm Socket through the hole on the Cap.
  2. Tighten the locking nut on the front with pliers.
  3. Slide over the main housing.
  4. Press the assembly onto the underside of the rails. (Friction fit).
  5. Connect the Servo Leads, taking care with the configuration (not orange wire to the left!)
  6. Plug in the Audio Jack.
  7. Feed the wires through the cable clips.
  8. Snap-on the Battery Pack if you have not already done so.
  9. Tidy any slack with an elastic band.
  10. All set!

DO NOT Switch On yet...

Step 23: SECTION H: Installing the Zocus App

Go to and navigate to the App Store, where you can download the App on iOS.
Follow the instructions to install the App. Switch on Bluetooth on your device.

Before your power-up the Zocus for the first time, you need to follow a few steps:

  1. Remove the Camera from the Zocus Rig.
  2. Now switch on the Battery/Power to the Zocus Rig.
    *It will make a small 'zzz' noise as the servos spin into their Mid-Positions*
  3. With the Camera off the rig, adjust the Zoom and Focus to the mid points of their rotations.
  4. Start the App.
  5. Move the sliders - you should see the motors turn.
  6. Put them back to the centred position.
  7. Put the Camera back on the Zocus Rig (everything should now be in a 'Mid Point configuration).
  8. Slowly slide the sliders back and forth until you the Zoom/Focus rings reach their natural limit.
  9. If you are happy that this covers the full range of the movements, you can then go to calibrate and set the Max and Min points. You can save different lenses.
  10. For storage, slide both sliders to Min. But be aware on start-up, the Zocus will go to Midpoint by default.

From now on, there is no need to calibrate or change any settings.

We hope to get some help with an Android version. Please get in touch if you are interested!

Step 24: Wireless Control of Your DSLR

As featured on the rest of the Big Life Fix show, James also used some other equipment, which was off the self. These include:

CamRanger (used to Pan & Tilt the camera, and allows access to all features which would otherwise have button controls on the back of the DSLR.

The original prototype was held to the wheelchair via sturdy Manfrotto Magic Arm Clamps. These are being 'upgraded' to fit James's wheelchair by a local branch of the engineering support charity, Remap.

If you'd like to know more about the story of the BLF check out the links below:

Design Modelling

BBC Make it Digital

Studio Lambert

Best wishes,


Design Now: 3D Design Contest 2016

Third Prize in the
Design Now: 3D Design Contest 2016

Epilog Contest 8

Participated in the
Epilog Contest 8

IoT Builders Contest

Participated in the
IoT Builders Contest