Nikon D90 Macro Autorail

Alright, finally the moment of truth. Time to make this into a real prototype on a protoboard. I've been dreading this, as the device has become so essential to shooting micro photography for me, but it's so delicate on a breadboard that it's kinda been hell babying it through all of these photos. 

Protoboarding went pretty smooth, although the rotary encoder I ended up soldering down had a different pinout then the prototype version, so that forced me to think on my feet a bit. I also accidentally tried pulling the motor / stage light power through the pro mini voltage regulator which resulted in a classic display of smoke and cussing. Amazingly it didn't kill the pro mini (as far as I can tell), so after some last minute reworking, everything seems fine.

This time around I extended the IR remote cable, and added a rubber band to it for easier mounting. I added a servo motor so I have 2 axis' of adjustment without having to reach into the stage. 

After hours of testing, everything works great! With the amount of power the motors and LEDs draw, I really need to add some decoupling caps and I'm probably missing some other obvious safety measures to keep everything happy, so version 3 will need to be rethought a little for better build quality. 

Some thoughts on feature enhancements: A second servo for 3 axis adjustment would be really nice. Also a smaller form factor for everything and attaching to the tripod directly would be amazing. Finally, being able to include adjustable, super bright LEDs for a flash replacement would also be really nice. Well see, maybe I can cook up some solutions for all that before I call it feature complete!

I keep a large stock of prototyping components, so luckily I didn’t have to order anything to build my first prototype. I started with a 3.3v Arduino pro mini. From there I’d need a HBridge Motor Driver to run the Stepper, a Neopixel ring for the stage light, a rotary encoder for input and an oled screen for output. I’d also need an Infrared LED for camera remote firing ( I use a Nikon D90, which accepts IR for remote fire which is super convenient in this case. )

Some challenges with the initial build: ofcourse, operating a device with so many jumper wires that are prone to falling out is not ideal. Also, I had to use 2 pins on the pro mini that are in the middle of the board and I didn’t bother attaching female pin headers, so the oled would disconnect every time the breadboard shifted. Finally, figuring out the pin and wire configuration for the hbridge was a lot more time consuming then I would have thought. As far shooting goes: I did have a complication with very light subjects (like dead bugs), though. If they’re not secured down, they will tend to shift when the stepper moves the stage. This sounds like a deal breaker, but it forced me to start using pins to pin down the bugs, which is actually better for many reasons.

Ultimately the prototype works out wonderfully, though! It improved the quality of my photos so much that I'm afraid of trying to build it on a protoboard and breaking it.  The neopixels are no where near bright enough to replace a flash, which I didn’t really expect to workout, but it’s super convenient as a prep light and I’ve used it a few times for edge light for adding alittle color to things. 

All in all it's been a great success, so far! Next I'll have to solder together a nicer prototype on a protoboard and put a real schematic together.