It was March 2014 when the development of the dp0 Quattro started "once again." As a matter of fact, there was a project to develop the dp featuring an ultra-wide angle 14mm lens (equivalent to 21mm in 35mm format), and it was before the dp2 Quattro, the first model of the Quattro generation, made its first appearance. It was SIGMA’s response to the customers’ request for "the dp with an ultra-wide angle lens," but the project disbanded before long. The time wasn’t ripe yet.
When Yamaki, the President of the company, casually expressed his interest in the old project that seemed to have been once abandoned, it received the attention in the company again. While the old project member welcomed it, they were also worried. They wanted to respond to the customers’ request. Meanwhile, developing a product involves enormous cost. Even though the focal length is traditional and common as an ultra-wide angle lens, this one is not an interchangeable lens but a lens permanently fixed to the camera, meaning only one focal length can be used. Will users accept it? It was natural for them to be careful in commoditization and the project became controversial. Will we make it or not? After many days of discussion, Yamaki said the following. "As you say, it may not sell. But, let’s make it. SIGMA is a manufacturer who tries. If we stop trying, we’re not SIGMA anymore." Then, one member made a decision. It was Tomoki Kohno, a lens designer / the Unit Acting Manager of the Product Development Unit 2. "If it won’t sell, let’s do our very best and make a historic 21mm." It was a "So What attitude" rather than a decision.
One thing Kohno had decided before he started designing the lens was "to make the distortion rate lower than 0.5%." Distortion is a phenomenon where straight lines of subjects (such as architectures and horizontal lines) are rendered as curved lines and this tendency becomes more common and difficult to correct with wider lenses. Yet, if the distortion rate is lower than 0.5%, one can say that the lens captures straight things straight with confidence. And, it became Kohno’s primary goal of the lens design.
At the time, the Product Planning Unit was examining the specification of the new dp Quattro with the ultra-wide angle lens. Because there was no major change in the body, they focused on the lens. The focal length has already been decided. Then, what about the maximum aperture? In order to set the sales price within a certain range, they couldn’t ignore the production cost. The maximum aperture doesn’t always explain the quality of a lens, and it’s difficult to produce an ultra-wide angle lens with a lower F-number. So, they concluded that the maximum F-number is between 3.5 and 4.5. And, this camera got its code name "0."
Manabu Tominaga, the Chief Clerk of the Product Development Unit 1 (responsible for entire camera design including lenses), was appointed to be the project leader of the "0" at the young age of 33. Tominaga’s job is to draw and finalize a mental picture of the camera and make it real. Upon receiving the decision made by the Product Planning Unit, Tominaga went to Kohno and said, "Let’s make it 3.5." It was natural for Tominaga to hope for a faster lens even a little. However, Kohno was thinking of F4. 3.5 and 4. The difference between them was just 0.5. But, Kohno, who had been involved in lens design for many years, knew it was a big difference. Of course, they could make a F3.5 lens and it would appeal to the market better. But, the 0.5 will sacrifice something, such as the goal: "the distortion rate lower than 0.5%." Kohno wanted to perfect fundamental performance of the lens more than to make it faster. In this regard, Kohno often used the expression "nature." What Kohno wanted to make was a lens with a good nature.
However, Tominaga didn’t withdraw and insisted on F3.5. He had someone bring the plan that was still at the sketching stage, and while pointing at the extra space in the lens-barrel, he said that there was some space to take a larger lens within the lens-barrel. In Kohno’s words, Tominaga "was ever so persistent." Tominaga had his hope that he could never negotiate as a project leader. If the spec order is "between F3.5 and F4.5," he wanted to overcome the highest hurdle. The two sides didn’t reach an agreement on this issue for a long time, but Tominaga finally understood Kohno’s decision and the battle over 0.5 was settled. It’s decided. The lens is F4.