Back in 1994, Kodak had a focal length reducer just like the SpeedBooster that made Metabones famous.
Back in the 1990s, digital photography was still just gaining a foothold and engineers were trying to figure out a number of problems and issues. It was done in a similar way to how the Metabones SpeedBooster gave cameras the ability to use lenses for larger format sensors while providing more light and field of view. Except for Kodak, it was to solve a significantly bigger problem around significantly smaller sensors. Before most cameras used CMOS sensors, they used CCD sensors–and really small ones at that. The sensors in those cameras would be laughable today for the professional photographer, and one of the big problems that needed to be solved was using available lenses.
A Google patent from years ago showed that Kodak was trying to solve pretty much the same problem with digital SLR cameras in those days. In the graphic above, we can see in part 50 how the optical design was created to take the lens designed for a 35mm camera system and use it on a digital camera. These days though, the system is used more for mirrorless cameras and DSLR lenses.
It works similar to how full frame lenses work on a cropped sensor camera. A Nikon 50mm f1.4 FX put on a Nikon D500 with a 1.5x crop factor will become a 75mm lens. And so that’s what Kodak was trying to solve: the problem of smaller sensors. According to the patent:
Various forms of optical adapters and converters are known that permit objective lenses designed for a certain size image format to be utilized for imaging on another size image format. However, most of the known rear lens attachments which are designed to be placed in a converging beam increase the image size instead of reducing it. Examples of such rear attachments are disclosed in U.S. Pat. Nos. 4,913,537; 4,840,466; 4,394,071; and 4,422,734.
It’s so interesting to look back into what they were doing in the past and see how it echos what’s being done today.