Working follow focus test setup!

Yes! It works!

It works a little better than the video shows, but it's a little too noisy right now, and still has some kinks to be ironed out.

Video with the Canon M500

Follow focus update

Some more parts for the follow focus came today, and things are starting to fall into place, so here's what I've got right now:

Here are all the parts, just laid out.

Here the lens is on the frame (rod system) in approximately the position it will be when mounted on the camera.

 Here are two phoctos of the gear used. The pitch is 0.08" (MXL)

Detail of the handle mount, press fit. (Also surprisingly strong!)

Close up of the drive belt on the lens focus ring

More of the same

This is how the whole thing will work, I will just slide that white mounting plate in, and mount the stepper motor on it (when it gets here), and mount the gear on the motor. The calipers are just to show size and to hold the gear in place.

Here it is from a different angle.

 That's where things stand right now, and so far it's working nicely. The new stepper motor should come soon. I ordered one from MPJA.com, only to be told that that model was not in stock, and the listing was a mistake. :( Oh well, they offered a different model that I think will work, for the same price, so I'll give that a try, and see how it works. The main thing is that I want it to run on 12 VDC, and have enough torque. The motor runs on 12 V, adequacy of torque awaiting testing.

 I can't really use it with the stepper motor I have right now because (1) I haven't figured out a good way to get enough torque out of it without blowing the driver transistors, and (2) it has a gear permanently affixed to its shaft, (of the wrong size) so I would have to cut it off to get it to work with the gear and drive belt.

 Just for reference, here are the parts used for the follow focus:

Gear: https://sdp-si.com/eStore/PartDetail.asp?Opener=Group&PartID=58730&GroupID=217

(Or similar, exact specs not important unless you are trying to get a ratio right)

Belt: https://sdp-si.com/eStore/PartDetail.asp?Opener=Group&PartID=51264&GroupID=213

(Or similar, length may be changed to suit application)

I didn't calculate the reduction ratio for the focus, because for now I don't need to, and it would add a lot of complications. I'm just going to get the whole thing working before I worry about that. After I have it working I can calibrate a dial, and tweak the ratios in the software. If at some point I try to make a commercial version, I may start thinking about things like that.

Hopefully I'll have the 3rd version of the .blend file ready to be posted soon, but that's all for now, until next time! 

Stepper motor success at long last!

Finally!
 I now have my Arduino driving the stepper motor!
This is the motor:

Here is the driver circuit:

And here's the whole test setup:

(As you may know, I'm not especially known for neatness, as long as it works I'm happy!)

Here's the oscilloscope I'm using:

And finally, proof that it really does work:

(apologies for the poor quality)

That's it! I'll keep working on it, and hopefully add a position control soon!