Actobotics Motorized Zoom for DSLR & EMotimo TB3

This DIY motorized zoom for a dSLR camera has been built to be used with the eMotimo TB3 for use with time lapse phototography. Specifically, I plan on using this to create vortex star trails of the night sky. Although there are ways to do this in Photoshop, I wanted to try and build a rig that would slowly zoom the lens in between each shot. The eMotimo TB3 allows for a external stepper motor that is usually used in motion slider photo ro video sequences, but I'll be using this to drive the gears to spin the zoom. I would assume that you could use this with other time lapse rigs that allow a shoot-move-shoot sequence. Most of the parts are Actobotics from ServoCity.com. Here is what you'll need:

www.ServoCity.com

• 2 x 3.75" Aluminum Channel (585443)
• 1 x 1.50" Aluminum Channel (5285440)
• 1 x 1/4"-20 Round Screw Plate (545468)
• 1 x 1/8" Hub Spacer (545372)
• 1 x 2.5" 1/4" Precision D-Shafting (634074)
• 1 x 1.75" 1/4" Precision D-Shafting (634066)
• 1 x 6-32 Socket Head Machine Screw (632106)
• 1 x 1/4" Tubing Spacers (633104)
• 1 x 1/4" Aluminum Set Screw Collar (9946K11)
• 2 x 1/4" Flanged Ball Bearings (535198)
• 1 x 72T 32 Pitch Aluminum Hub Gear (1/2" Bore) (615198)
• 1 x 24T 32 Pitch Gearmotor Pinion Gear (615250)
• 1 x 0.770" Set Screw Hub (545548)
• 1 x Planetary Gearmotor Mount B (555174)
• 1 x 1/4" to 6mm Set Screw Shaft Coupler (625106)

Amazon

• Arca Swiss Adapter Plate

Stepper Motors Online

• 100:1 Planetary Gearbox Nema 17 Stepper Motor

Sparkfun

• Molex Jumper 4 Wire Assembly

Redrock Micro

• 1 x Microlens Gear, Blue, Size B

I'm not going to post step by step instructions on how to put Actobotics parts together. Hopefully, you'll be able to figure out what goes where by the pictures above. Depending on what dSLR camera and lens you have, you may to alter the design, and potentially get a different size lens gear. The Arca Swiss plate adapter mount is a nice upgrade because it allows you to slide the camera into the hub gear for a perfect fit. I also originally used a different stepper motor, and purchased the 100:1 geared motor to slow down the speed. Considering that the lens doesn't have to rotate very far, having a slower motor allows for more precision zooms. One issue I ran into was that the planetary gear mount from Servocity does not line up with the planetary stepper motor mounting holes, and had to "alter" them slightly with a drill.

*** Caution: The 100:1 motor has a lot of torque. If you are not careful, you could damage your zoom lens if you try and turn it too far.

The connector for the TB3 requires a Molex connector. Here is the wiring schematic:

• Black Motor -> Black Jumper
• Green Motor -> Red Jumper
• Blue Motor - > Orange Jumper
• Red Motor -> Yellow Jumper

This could also be used as a motorized follow-focus rig with a little tweaking. I'll be using it specifically for astrophotography for now. If I ever pull the trigger on the new eMotimo Spectrum, I'd be able to do a motion time lapse with zoom or variable focus. Sounds fun!

I will update this thread with pictures once I get a chance to get outside. It is winter in Wisconsin, and haven't had a clear night that wasn't like 5 degrees outside. The rig tested well inside, so I can't wait to give it a shot on a dark moonless night!