# PhotoStepper

A stepper motor controller for use in photography.

![PhotoStepper](example_images/220222_controller.jpg)

This is a device that can be used to control a stepper motor and a camera, to
make a defined number of photos with a defined movement in between. A stepper
motor can be attached to a rotating platform or to a linear drive, so either
the object or the camera can be moved between the pictures.

## Hardware

The device consists of the following components:

- Arduino Uno, the brains of the operation
- LCD & keypad shield, as the user interface
- an A4988 stepper motor driver
- a 100uF capacitor
- two PC817 opto-isolators
- two 1k resistors

The circuit is pretty simple:

![Circuit](circuit/photostepper_bb.jpg)

Atop of that, I used an M13 connector for the stepper motor and a 2.5mm stereo
phone connector for the camera. To interface my camera, I had a ready made
cable from a remot camera controller (Ayex AX-5). The whole thing is powered by
a 12V power supply, connected directly to the Arduino.

This is the ideal case for the build:
https://www.thingiverse.com/thing:142282/files

## Software

This project makes heavy use of the following libraries:

- [ArduinoMenu 4](https://www.arduino.cc/reference/en/libraries/arduinomenu-library/) (v4.21.4) for the menu structure
- [StepperDriver](https://www.arduino.cc/reference/en/libraries/stepperdriver/) (v1.3.1) for motor control
- [AnalogKeypad by Makuna](https://www.arduino.cc/reference/en/libraries/analogkeypad/) (v1.1.1) for reading input keys

## Menu structure

The main menu offers the following features:

* Jog

  Up and down buttons move the motor manually, pressing the buttons for more
  than a second doubles the speed.

* Configuration

  General settings for the device:

  * Settle time (tSettle, default 1000ms)

    Pause between motor movement and camera triggers, to avoid blurred images
    because of a shaking camera setup.

  * Focus time (tFocus, default 1000ms)

    Half-press of the shutter button, time to let the camera focus. Usually you
    want to use manual focus when using this device, so it doesn't hurt to
    lower this time.

  * Shutter time (tShutter, default 1000ms)

    How long to press the trigger. Note that you have to setup the exposure
    time on your camera before shooting, this is really only how long the
    button is pressed.

  * Return (default: On)

    Reverse any movement to starting point after shooting the whole scene. This
    allows to repeat the scene with the same parameters.

  * DarkenLCD (default: Off)

    Turn off LCD backlight while shutter is open, used to avoid scattered light
    when shooting in the dark with long exposure time.

* Scene

  Settings for a particular scene:

  * Steps (nSteps, default 10)

    Number of steps for this scene. You want to take enough pictures to cover
    the whole subject.

  * Distance per step (distance, default 0.5mm)

    How far to move between the steps. This should be set lower than the
    estimated depth of field for the setup.

* Run

  Run the whole setup, starting with settle time and ending with returning to
  the starting point.

## Usage

I built myself a linear rig to move my camera along the scene:

![Linear rig](example_images/220222_linear_rig.jpg)

The rig is mounted on a tripod, my camera with all the needed equipment for
macro photography atop of that.

Then I setup the scene I want to capture. I focus on the main feature of my
motive, set the camera to manual focus and setup exposure time and aperture.
After a testshot I can estimate the depth of field that gives me a sharp
picture. The I use the jog function of the device to place the camera closer to
the object, so the focus plane moves behind the object. I estimate the total
depth of field I want to get in my final picture and set the correct values for
my scene.

After everything is prepared, I select Run to capture the whole scene. The
camera takes a picture, moves slightly back, takes the next picture, and so on.
When the set number of steps is reached, the camera gets moved back to its
original position, that gived me the chance to make slight changes to the
object and rerun the program with the same parameters.

## Example results

This is the first image that was made using this project:

![Extreme closeup of a coin](example_images/220213_macro_cent.jpg)

Depth of field for my setup is a little more than 1mm, so this image is
composed from 30 different shots, each 1mm apart. Here's an animation of the
non-fused images:

![Animated focus stack](example_images/220213_macro_cent_-_animation.gif)

The images were taken as JPG. For some reason the align-program did strange
things with my full size images, so I reduced them in size first -- it's only a
first test:

```
for i in *.JPG; do convert $i -resize 50% $i.tif; done
```

Then I was able to align all images using a tool from the [Hugin](http://hugin.sourceforge.net/) package of my distribution:

```
align_image_stack -ma aligned_ *.tif
```

This command not only aligns all the images, the -m options optimized the field
of view. In a focus stacking setup, the camera gets moved towards or away from
the object, so not only the focus plane is moved but the whole objects gets
bigger or smaller. With this option, all images are resized, so the object
stays in the same position and size throughout the full stack of images.

Once this is done, I created the final image from my stack of photos using [Enblend](http://enblend.sourceforge.net/):

```
enfuse -o result.tif --exposure-weight=0 --saturation-weight=0 --contrast-weight=1 --hard-mask --contrast-edge-scale=0.5 aligned_00*
```

## License

This work is licensed under the Creative Commons Attribution-NonCommercial 4.0
International License. To view a copy of this license, visit
http://creativecommons.org/licenses/by-nc/4.0/ or send a letter to Creative
Commons, PO Box 1866, Mountain View, CA 94042, USA.