One of the most common complaints about Nikon’s massive NIKKOR Z 58mm f/0.95 Noct lens is the fact that it doesn’t have autofocus. But according to Nikon, if they had included an AF motor, the size of the lens would have increased “far beyond imagination.”
This comically worded revelation came during an interview published by Japanese publication Xitek. In an issue dedicated to the development of the Nikon Z-Mount, the publication had the chance to interview some of Nikon’s most prominent engineers including Hiroyuki Ishigami and Tomoharu Fujiwara.
When asking about the development of the latest Noct lens, Xitek brought up the lack of autofocus, and after Ishigami-san admitted that “at the beginning of planning, I hoped to adopt AF,” Fujiwara-san explained the reasons why MF was ultimately chosen (Google translation, emphasis added):
Of course we have also studied AF, and driving the focus lens itself can be done. But the action is quite slow, not as fast as manual operation. At the same time, the increase in size is far beyond imagination. It cannot be driven by the existing ultrasonic motor, and a larger actuator must be arranged outside the lens.
Therefore, if you really want to achieve AF in the f/0.95 lens, this optical type will not work. You need to reduce the focus lens and use the internal focusing method. But using this method will result in a longer overall length, which means that peripheral components will also increase, and the lens will still be larger and heavier than it is now.
Even if such a lens is made, even if the product is very special, it may not be established as a product, so we gave up AF.
You can hear more about the development of the Z-Mount from the engineers who created it in the video below:
In the end, while this lens is clearly a statement piece, it still had to be usable. If you thought the current version was ridiculously large for a standard focal length, you can only imagine what it would look like if they tried to add an internal focusing motor capable of moving that much glass.
Plus, it would have made this expensive lens—already no bargain at $8,000—an even more expensive prospect to Nikon owners who are not used to paying Leica prices for their glass.
(via Mirrorless Rumors)