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OpenCamera - 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 Box Camera
Media 120 Roll Film
Objective 65mm f/5.6 Single Element, Coated
Viewfinder Waist-level Brilliant finder
Shutter Electromechanical single-leaf, 1/125-1s + 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)

Parts List

Electrical

Part Qty Source Notes
Adafruit Trinket 5V 1 Adafruit
Adafruit Quarter-size Protoboard 1 Adafruit
Transistors, TIP120 2 AdafruitPerhaps a bit overkill
Diode, 1N4001 1 Adafruit
Solenoid, 5V 1 SparkFun
Rotary Switch, 10 position BCD DIP 1 JamecoCould be substituted by a 10K trimpot
Rocker Switch, SPST 1 Jameco
Resistors, 1/4W, Asst. Values ? eBay1% tolerance recommended for binary adder
Battery, 7.4V 500mAh Turnigy LiPo 1 HobbyKingYou will also want a charger
Connectors, JST PH 4 eBayIf you want to avoid hard wiring
Connectors, JST BEC 1 eBayFemale battery connector
Momentary Button, SPST w/ LED 1 eBayAny 12mm momentary button will do

Optical

Part Qty Source Notes
PCX Lens, f=30mm, d=15mm 2 Anchor OpticsBrilliant finder lenses. A tad pricey. Coated lenses available. 23084
Positive Meniscus Lens, f=80mm, d=19mm 1 Anchor OpticsObjective lens. Coated. AX73931
Mirror, 17 x 23 x 1mm 1 Anchor OpticsBrilliant finder mirror. AX31417

Mechanical

Part Qty Source Notes
M3 CSK Machine Screws 10 McMaster
M3 Hex Nuts, Thin 10 McMaster
1/4"-20 Square Nuts 1 McMasterTripod Nut
Spacer, L=2.5", d=0.25" 2 McMasterMakeshift film rollers
Ball Bearing, d=3mm 1 eBayLens 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 McMasterFilm roller screws
Torsion Spring 1 McMasterShutter return spring
Stainless Steel Plate 1 McMasterMat'l for laser cut parts
Magnets, d=3/8", t=1/16" 2 eBay, CMS


Shutter Circuit

I'm not an EE, so be warned! Only the breadboard layout of the Fritzing file is accurate. The Perma-Proto board nets are not routed.

Fritzing (You may need to download Fritzing HERE)

Arduino Code

You'll need to install the Arduino IDE and Trinket drivers available from Adafruit. Adafruit has a version on the Arduino IDE compatable with Trinket HERE. You still need to install the Trinket USB drivers HERE.
The Trinket bootloader isn't as plug-and-play as say, an Uno.
Arduino Code

Part Files

Here are all of the part files you need to make Lux for yourself. The STL files can be printed by a service like i.materialise or Shapeways, using the "Polished White Polyamide" or "Polished White Strong & Flexible" materials, respectively.
STL FILES

You will need this file to make metal parts for the aperture wheel, shutter, pressure plate, focus distance scale, etc. A laser cutting service like Pololu will know what to do with this file. (Note! There is a typo - these should be cut from 0.025" stainless steel)
FLAT PARTS

Exploded Diagrams



This section is a work in progress.

Assembly Images


Sample Photos


Thoughts

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.

  • Future Work

    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.