DPReview is the world’s most popular dedicated enthusiast digital photography site. In March 2015, DP Review visited the Sigma Aizu factory in Fukishima, Japan and created this virtual tour of images through the factory.
On our recent visit to Japan to attend the CP+ show in Yokohama we were fortunate to be invited to tour Sigma’s factory in Aizu. The Aizu factory is where all of Sigma’s lenses are manufactured, including the company’s impressive new ‘Art’ line of primes. Covering an area of around 58,000 square meters, this slideshow is a virtual tour of the factory, in the company of Kazuto Yamaki, Sigma’s CEO
These boxes contain the raw material for Sigma’s lenses – glass. Sigma uses glass supplied domestically by Hoya, and the stockroom is full of boxes and boxes of it. Because Sigma’s supply chain is mostly local (unlike larger manufacturers who outsource components and assembly across the globe), the factory was able to return to limited production within only two days of the devastating earthquake that struck Japan in 2009. These cakes of glass, supplied by Hoya, will be formed into lens elements during a lengthy process of grinding, centring (to make sure that the optical centre of the element is where it should be) and polishing. It’s hard to discern, but follow the stream of water and you’ll see a lens element in the process of being ground into shape.
A worker adjusts one of a bank of lens element polishing machines on the factory floor. When I spoke to Mr Yamaki last year he told me that most of the people who join the company stay with Sigma until they retire.
A closer look at a lens element, in the process of being polished.
Lens elements awaiting the next stage in the lengthy shaping and polishing process.
After lens elements have been ground, polished and checked, they’re coated. This image shows elements being loaded into one of several large disc-shaped trays, prior to being moved into the huge vacuum evaporation machines which apply the coatings.
After coating, the lens elements are placed into groups, which are then assembled into the final lens. This shot shows workers checking and assembling lens elements into groups. The elements are held in place initially by friction, inside their TSC trays, before the TSC is heated at the edges and sealed to lock the elements into place. This type of construction replaces the much more involved traditional method where glass elements were held in place by metal bezels screwed tightly into the barrel.
Time for lunch! Like many large factories, Sigma’s Aizu facility contains catering facilities for its workers, who eat here in staggered breaks throughout the working day.
Modern lenses are complex things. This is part of a lens barrel, with grooves for the various cams that keep the groups of elements moving smoothly as the lens is zoomed and focused.
These tiny pins are the main contact pins used in the hotshoes of Sigma’s cameras, prior to being chromed. Wherever possible, to save cost Sigma uses standard-sized pins and screws but Mr Yamaki tells me ‘designers are very good at designing non-standard parts’.
All of this machining creates a lot of waste metal, which is packed up and sent away to be recycled.
Two engineers in Sigma’s prototyping department review designs for a top-secret new lens design, which may or may not make it into full production.
Sigma’s Aizu factory uses a mixture of old and new machinery. Here, an engineer in the prototyping department adjusts one of the older machines.
. Here, a trainee reviews a virtual model of one of Sigma’s DP-series cameras on a computer.
Although there are computers everywhere in Sigma’s Aizu factory, racks of drawings and blueprints can still be found in various areas around the factory floor.
These are pellets of glass-reinforced plastic, (Sigma calls it ‘Thermally Stable Composite’) used in the construction of various components in Sigma’s lenses, prior to being heated up and shaped into their final form. Although sometimes dismissed by the uninformed as being inferior to metal in the construction of precision optics, this kind of material can be shaped in ways that would be impossible with metal, and much more simply, too. Mr Yamaki tells me that injection-molded parts can be created with tolerances of +/- 1 micron.
An engineer in the injection molding area of the factory adjusts one of the ‘take out’ machines by hand. As you might expect from the name, the take out machine lifts finished parts from the injection molding machine and sorts them into boxes where they move on to the next stage in assembly.
This tray contains injection-molded TSC which will house contain lens elements. According to Mr Yamaki, TSC has similar thermal properties to aluminium and is considerably stronger than conventional glass/polycarbonate materials.
A huge amount of work in the Aizu factory is still done by hand. Here, a worker is hand-painting the white checkmark onto a row of focus mode switches. So next time you use one, spare a thought for the person who does this, for hours every day.
Do you recognize those shapes? They’re aperture blades – or rather the silhouettes of aperture blades, once they’ve been punched out.
Here are the blades themselves, after being punched out and machined.
Rather than drilling, some of the finer holes which need to be made in various components (or normal sized holes in particularly hard metal components) are created through very precisely controlled electrical discharge. Electricity is discharged through these pins (shown here prior to installation in the electrical discharge machine).
A tray of lens mounts after machining, waiting to be chrome plated.
Many of the components inside Sigma’s lenses, including the mounts, are chrome plated. Normally a highly toxic procedure, Sigma uses a trivalent chromium process which – while more complicated in some respects – is safer for Sigma’s employees. Mr Yamaki tells me that this was a personal mission for his father.
This is a rack of lens mounts, following chrome plating.
Anodization is another important process, which increases corrosion and wear resistance. Here, a rack of metal components is lowered into an acid bath as part of the anodization process. This part of the factory is hot and smelly – a distinct contrast to the clean, cool and unexpectedly quiet atmosphere in most of the facility.
The unfinished parts of two lens barrels, awaiting final touches and assembly.
Here, a worker in Sigma’s Aizu factory prints lettering onto the barrels of one of the company’s lenses, using a silk screening process.
Once the printing is complete, the barrels are checked and put into racks awaiting final assembly. According to Mr Yamaki, his father came to value the staff at Sigma’s Aizu facility because of the character of the local population, which places a high importance on loyalty and hard work. Dave Etchells over at Imaging Resource retells the story (also recounted to me) better than I could here.
specification. This stage makes good use of Sigma’s ‘A1’ testing rig for MTF measurement. The A1 is built around the company’s ‘Merrill’ generation APS-C Foveon sensor, which for full-frame lenses is shifted to create four overlapping exposures, from which edge to edge MTF measurements can be taken.
Sigma Aizu Factory Tour with DP Review