A case for depth perception

DN Staff

May 20, 2002

11 Min Read
A case for depth perception

In many ways, Dave Bradley is the least likely person to tote a disposable camera with him on leisure outings. As a commercial photographer in Boston who spends his days in his studio and on location shooting artistic scenes and setups for ad agencies and magazines, he has a roomful of cameras that cost $3,000 each.

The Max Water and Spot one-time use camera operates deeper than others Kodak says. It's tested for 35 ft., vs. 17 for similar cameras, but at least one Kodak engineer used it at 70 ft.

But, there he is whitewater rafting, firing off shot after shot with a disposable camera that he will never use again when he finishes the roll of film.

"It's lightweight, easy, fun, and I don't have to worry about ruining it," he says.

If that's the way a professional looks at it, imagine the way the rest of the population feels. No wonder disposables-or, one-time-use cameras, as they are called in the trade-are the fastest-growing segment in photography. Consumers bought 300 million of them in 2001.

Which is why Kodak and Fuji, among others, have invested heavily in development of these easy-to-use products.

Innovations in design. Now, by blending engineered materials, extensive software use, and collaboration with vendors as well as other internal departments, Kodak engineers have developed a new single-use camera it says takes the technology to new heights-or, rather, depths-of ruggedness and versatility.

The 27-exposure Max Water and Sport, which debuted at the Photographic Marketing Association Show in Orlando in late February, boasts several innovative features, Kodak engineers say. Among them:

  • Increased depth performance. Thanks to the use of polycarbonate and a stacked viewfinder that forms a rigid internal column, the Max Water and Sport withstands potentially crushing water pressure and operates safely in 35 ft of water vs the typical 17 ft for most one-time-use cameras.

  • Improved picture quality. A two-element lens that Kodak originally designed for one of its reloadable cameras reduces distortion and, says Kodak, produces the sharpest images available in a single-use camera. The two lenses, made of optical-grade acrylic and polystyrene, correct aberrations from a single lens and produce better image sharpness at the outer edge of the image focal plane. Kodak engineers say the dual lenses focus light rays with four surfaces rather than the two with a single lens. Other single-use cameras use only one lens.

  • Lower cost. By combining parts, eliminating a rubber dome seal and internal plunger, and incorporating a leak indicator on the camera to save investing in expensive leak-testing hardware, engineers significantly lowered their costs. As an added benefit, they used some of their savings to pay for the more expensive polycarbonate for the outside housings.

A Kodak engineer checks the housing for the new Max Water and Sport one-time use camera. It operates safely at 35 ft. due to a polycarbonate housing that won't crack or shatter under pressure, two-shot molding that co-injects a rubber seal to protect the front and rear housings, and a stacked viewfinder that forms a rigid column within the camera.

Pressure points. Snorklers and sport divers are some of the most frequent users of single-use sports cameras, but when they take them underwater they put the cameras in harm's way. Water pressure can cause cameras to leak profusely. Additionally, the pressure can activate the shutter at any time, whether the diver wants to take a picture or not. It normally takes 3.5 lbs of pressure to activate a shutter, but even at 10 ft of depth, pressure under water can exceed that. And, once the shutter engages, pressure can keep it down. Result: You get only one picture, and it may not be the one you want.

The off-the-shelf polycarbonate Kodak engineers chose is stronger and more impact resistant than the polystyrene normally used for such cameras. And, says Design Manager Steve Smith, it has the added benefit of being resistant to suntan lotion, which can gum up a lens cover and distort pictures.

Using Unigraphics CAD software, engineers produced a design that stacks the camera frame and front and rear housings in a rigid column. Most cameras have designed-in air space for clearance, which adds depth to the camera. Kodak's stacking innovation yielded a smaller camera with a more robust design, Smith says. The viewfinder column adds strength to the camera while eliminating one viewfinder element. The rear viewfinder is molded into the rear housing, and the front viewfinder is molded into the trigger plate, combining three parts into two. "In effect, the static camera component internally becomes a support column, " says Smith.

The internal-column design also enabled Smith and his team to minimize the thickness of the more costly polycarbonate housing. "We used empirical data to start and created several designs of different thicknesses and shapes in Unigraphics," says Smith. "We verified the geometry in Abaqus finite element software."

Two-shot molding. Critical to the design was a two-shot molding process for the polycarbonate housing which co-injected rubber over the polycarbonate to form a rubberized trigger and leak detector. The two-shot molding also enabled engineers to design a strong fracture-resistant trip button over-molded with a water-tight rubber skin.

To avoid the problem of water pressure activating the trigger, engineers incorporated a toggle-type trip lever where pressure in both directions is equal.

Molding the trip button into the rubber provided a torsion beam that simplified the linkage normally required to get the trigger to work internally when users push it. "We were able to eliminate the seals you normally need and eliminate the internal plunger," Smith asserts. "Typically, a linkage requires two-to-four extra components to achieve what we have in a single, multi-functional part."

But they did need an o-ring seal for the wind-knob area on top of the housing, and they attempted forming it with the second rubber shot in the molding operation. It wasn't easy. "We molded that o-ring seal from rubber with a high creep resistance," Smith says. "We had to find the best shape that would resist water pressure and not leak."

He and his team decided they needed more life testing to understand the effects on creep and the risks to the customer. "This was about a two-cent cost opportunity we may pursue in the future," Smith says. "Ultimately, we decided to move forward with history we were comfortable with, a separate nitrile rubber o-ring."

Engineers stacked the view finder to form an internal column that added strength to the camera.

Water leaks are lethal to underwater cameras, so the engineering team designed an integral leak detector in the camera's front housing. It consists of a 0.75-mm-thick rubber membrane over a 9-mm-hole in the polycarbonate front housing at the bottom of the camera. An automated fixture applies a vacuum that establishes lower pressure inside the camera as the wind knob and housings are assembled. The membrane deflects during this process. A sensor on the assembly line detects the deflection, which indicates a functioning seal. "Without this leak indicator, we would have had to invest in a $200,000 piece of testing equipment and use two operators for inspection on the assembly line, which would have added to the cost of the camera," Smith says.

Team effort. In these days of fierce competition and shortened design times, no design team can afford to operate alone. In fact, under manager John Erickson, Kodak's one-time-use camera division strongly promotes extensive and frequent collaboration on all design projects.

The design team for the Max Water and Sport included mechanical engineering, manufacturing engineering, molding engineers, optical engineers, materials engineering, industrial designers, recycling specialists, and a service group that did the finite element analysis runs with the Abaqus software. Smith led the effort and met weekly with representatives of Kodak's purchasing department.

All members of the team were in Rochester, though in separate buildings on the Kodak campus. Team members talked face to face and exchanged CAD files. Additionally, the team shared its Moldflow electronic data with a molding company in Germany that provided the tools and equipment for manufacturing the two-shot housing.

Design/Manufacturing Manager Smith personally handled the communications with the manufacturing staff since he used to work in that department and had an instinctive feel for the questions and issues they would raise. He and his manufacturing counterparts jointly studied Excel spread sheets that detailed assembly fallout from previous sports cameras so they could avoid missed opportunities on this project.

Industrial design was a critical element of the project, and Smith's team worked closely with the industrial-design staff, which used Alias software. "Several iterations of geometry went back and forth between industrial and mechanical de-sign," says Smith. The mechanical design team also collaborated with a separate engineering group working on another camera at Kodak, exchanging Unigraphics files so they could use the same chassis for their individual designs. After settling on final specs for the camera, the design team briefed the operations staff on the elements of the final assembly, and the operations staff determined the assembly equipment to use.

Says Erickson, "Collaboration was essential with all parties, internally and externally, because we were under pressure to get the product out to market." Complicating the process was the 30-week lead time for procuring the front-housing manufacturing equipment. "We had to crunch down development time and prove out the geometry before giving it to the German molding company," he says.

Did the collaboration help? You bet, says Erickson. "The result was a lower-cost, robust product with superior picture quality and water-depth performance."

On the water-depth performance, at least one independent expert agrees. Engineer and consultant Steve Hines, president of Glendale, CA-based HinesLab Inc. and inventor of several camera innovations, says that users can be sure with the polycarbonate material that the camera will not crack or shatter under pressure as would many other plastic case materials. Indeed, Kodak engineer Dave Dow, a SCUBA diver took an early version of the camera to a depth of 70 ft in murky Lake Ontario to photograph the sunken schooner Henry Rooney. "It worked great even at that depth," he says.

As for the ultimate measure of success-market acceptance-engineers will have to wait. The camera goes on sale this spring and will be available worldwide later. Price? Undetermined as of this writing, but Kodak says it will be significantly less than the typical $1,200 for an underwater camera.

Typical properties for clear, general purpose materials

Kodak engineers chose non-glass-filled polycarbonate for the Max Water and Sport camera's front and rear housings to give it the strength to resist water pressure. In general, it's similar to the material used in street lights and city buses. Most single-use cameras use polystyrene. Here's a general comparison of the two materials:

Polycarbonate (non-glass-filled, such as GE Lexan 121R)

Tensile strength

Flexural modulus

Impact strength

Max. use temperature (no load)

Polystyrene (such as Nova 1300 GPPS)

Tensile strength

Flexural modulus

Impact strength

Max. use temperature (no load)

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