Katsunori Tomita

4th Optical Designing Section, 1st Designing Department, Optical Engineering Division, NIKON CORPORATION

Mr. Tomita took charge of optical design from the stage of prototype manufacturing. He was involved in mass-production design, and completed the WX series after much effort and hard work. His background lies in designing space- and astronomy-related equipment including optical observation equipment for satellites and astronomical telescopes.

A staff united in an attitude of "no compromise".

"They might be difficult to design, but if we could achieve success, these would be the ideal binoculars. Astronomy enthusiasts would go crazy about them."
Mr. Tomita, who joined the development team just as prototype manufacturing was commencing, looks back at that time. At that point, the specifications and design were almost decided, and the optical design fundamentals were more or less fixed. The WX 7x50 IF binoculars were smoothly moving on from functional prototype to the stage of prototype manufacturing.

However, the production of the WX 10x50 IF binoculars was beset by problems.
The team hit a wall in the process of balancing optical aberration, which brought production to a halt.

Due to the binoculars' wider apparent field of view, issues arose that the design software seemed unable to anticipate and that could only be seen for the first time during actual viewing. After inheriting Mr. Fukumoto's functional prototype, Mr. Tomita redesigned and reexamined the eyepieces and objective lenses.
The question of how to resolve contradictory elements in a balanced manner lies at the heart of optical design. "We had a hard time searching for the ideal point in a comprehensive optical design that also takes into consideration the human eye. Not only that, but the entire chromatic aberration balance had to be adjusted to bring it closer to an ideal solution.

*WX binoculars (left) and the first production prototype manufactured in 2015 (right).

We also had to take all possible countermeasures against stray light. If we had neglected this, all of our developmental efforts would have been ruined instantly.
I couldn't say this until now, but they were tough times; judgments in the department could be quite unforgiving."
"I was waiting such a long time for the first prototype to be completed, and was the first one to look through the binoculars. I'll never forget the thrill."

At the stage of mass production, unexpected problems also often occurred. During that time, Mr. Tomita was able to rely on the office's resident experts.
He asked acquaintances he had worked with in the past through customized products design projects, and they gladly shared their knowledge and advice.
"We never compromise on optical performance. To carry through on that spirit, extensive knowhow in optical design is essential. Nikon has accumulated immense knowledge and experience, and a large part of this project's success was having access to that expertise with the entire company's cooperation."

"There were diverse issues that arose during this project, but we overcame them all thanks to the support of the whole company.
When my boss at that time said, 'This image quality surpasses anything else in the binocular category'. I was truly glad."

According to the three key developers, the greatest struggle they faced in the WX series binoculars development was the prism.
WX binoculars use Abbe-Koenig prisms which feature total reflection on all surfaces and have a high transmission rate. Because the width of these prisms is narrow, the binoculars' body can be relatively slim. The prisms employed in the WX binoculars feature extremely high precision but are also extremely difficult to manufacture. Without them, however, a super-wide viewfield cannot be achieved.

Mr. Tomita, "The prisms used in WX binoculars deliver truly astonishing performance. They were created literally by the whole company. The question of how such a high-accuracy and high-performance prism could be mass produced is one of the main reasons it took 10 years to release.

Thanks to the incessant progress of optical technology, we were finally able to successfully achieve the finished product."