Lux

 

Introduction

This page details my efforts to design a completely homegrown camera. Until now, all of my camera- building efforts utilized parts repurposed from old, obsolete cameras, and for good reason. Each constituent part of the modern camera, from the shutter, lens, aperture diaphragm, and film transport, are much too complex and delicate for the average hobbyist to reproduce. Borrowing parts from old cameras is usually the go-to solution for most DIY'ers (myself included), however I don't think this is a sustainable technique.

My goal is to design and produce a fully-fledged camera, using easily purchased off-the-shelf components, without having to rely on anything pulled from a potentially valuable piece of equipment. A secondary goal is also to make this camera completely open source through rapid-prototyping techniques such as laser cutting and 3D printing, and the Arduino physical computing platform. 

 

Specifications

Type: 6x6 cm box camera
Media: 120 roll film
Objective: 65mm f/5.6 positive meniscus lens, coated
Viewfinder: Waist-level "brilliant" finder
Shutter: Electromechanical single-leaf, 1/125s-1s + B&T
Aperture: Rotating diaphragm, f/5.6-32
Dimensions: 7.9 x 9.4 x 11.7 cm
Construction: SLS Polyamide (body), Stainless Steel (shutter, aperture assembly)

Parts list

Electrical

Adafruit Trinket 5V  [1]  Adafruit
Adafruit Quarter-size Protoboard  [1]  Adafruit
Transistors, TIP120  [2]  Adafruit (Perhaps a bit overkill)
Diode, 1N4001  [1]  Adafruit
Solenoid, 5V  [1]  SparkFun
Rotary Switch, 10 position BCD DIP  [1]  Jameco (Could be sub. a 10K trimpot)
Rocker Switch, SPST  [1]  Jameco
Resistors, 1/4W, Asst. Values (1% tolerance recommended for binary adder)
Battery, 7.4V 500mAh Turnigy LiPo  [1]  HobbyKing (You will also want a charger)
Connectors, JST PH  [4]  (If you want to avoid hard wiring)
Connectors, JST BEC  [1]  (Female battery connector)
Momentary Button, SPST w/ LED  [1] (Any 12mm momentary button will do)

Optical

PCX Lens, f=30mm, d=15mm  [2]  Anchor Optics (Brilliant finder lenses. P/N 23084)
Positive Meniscus Lens, f=80mm, d=19mm  [1]  Anchor Optics (P/N AX73931)
Mirror, 17 x 23 x 1mm   [1]  Anchor Optics (Brilliant finder mirror. P/N AX31417)

Mechanical

M3 CSK Machine Screws  [10]  McMaster
M3 Hex Nuts, Thin  [10]  McMaster
1/4"-20 Square Nuts  [1]  McMaster (Tripod Nut)
Spacer, L=2.5", d=0.25"  [2]  McMaster (Makeshift film rollers)
Ball Bearing, d=3mm  [1]  eBay  (Lens helical bearings)
Screws, No.1 L=1/4"  [1]  McMaster
Screws, No.0 L=3/8"  [1]  McMaster
Screws, No.0 L=1/8"  [1]  McMaster
Machine Screws, 4-40 L=1/4"  [1]  McMaster  (Film roller screws)
Torsion Spring  [1]  McMaster (Shutter return spring)
Stainless Steel Plate  [1]  McMaster (Mat'l for laser cut parts)
Magnets, d=3/8", t=1/16"  [2]  eBay, CMS

 

Source Files

Be forewarned! This was one of my first forays into EDA software. I choose to learn Fritzing, and in hindsight... I chose poorly. Below is the breadboard layout of the Shutter circuit. Please note that only the breadboard layout of the Fritzing file is accurate. 

Arduino code is super-duper simple, and should work with v1.6 of the IDE (but not tested - worked on v1.0).

STL files can be printed by Shapeways or i.Materialise (I prefer the former), in Polished White Strong & Flexible or Polyamide.  I think these would be really hard to print on an FDM machine, for what it's worth.

Flat parts can be laser cut by a company like Pololu.

 

Exploded Diagrams

 

Assembly Images

 

Sample Photos

 

Thoughts & Recommendations

At the time of writing, I've run about a roll-and-a-half of film through Lux. Thus far it's been a pleasure to use, with a few nagging issues (see below). It really works about the same as any other old film camera - turn on, make exposure adjustments, frame, shoot, wind, and repeat. With color negative film, the lack of an exposure meter isn't too much of an issue - in most outdoor conditions it's possible to use the Sunny 16 rule and make adjustments from there. Loading and unloading film is pretty easy, winding and counting frames is a breeze. And so far - no light leaks! 

My main complaints:

  • No access to battery without disassembly: This one is pretty bad. You need to unscrew the front plate, front assembly, and untape the battery to remove it. You have to do the same to charge it. Yikes.
  • Framing is difficult: The viewfinder is very bright and usable. But lining up the horizon and framing shots takes a bit of imagination. Plus it's pretty small.
  • Shutter maximum speed: The shutter tops out at 1/125s, which is a little limiting. It's two stops slower than most "modern" leaf shutters. Perhaps this could be improved by making the shutter leaf out of a lighter or thinner stock

I think I would like to next attempt a TLR based on the Lux body. Here are some features I'd like to implement:

  • Push-button power breakout: Adafruit sells these. It would allow the camera to turn itself off to save power.
  • Custom PCB's for main board and rotary DIP breakout: I've already got these on the way from Fritzing Fab. They were about $16, excluding checking and shipping costs.
  • Removable battery: Nuf' said.