An interesting new patent application from Canon details a series of potential lens designs with an adjustable soft-focus feature.

Japanese patent application number 2018-97240 lays out the groundwork and schematics for four different full-frame camera lens designs that feature a dual-focus system: a 58mm F1.4, a 35m F1.8, a 105mm F2 and a 70-200mm F4.

According to the patent application, the first focusing module would be used for the traditional purpose of focusing on the subject matter. The other module, however, isn't for the sake of focusing, but to intentionally soften the image using spherical aberration.

The patent application details two specific challenges designing such a lens: firstly it covers a way to focus this two group design (which is a challenge to do when spherical aberration is present in the image). Secondly it describes a way to able to vary the amount of soft-focus, so you can add as much or as little spherical aberration as you see fit for the scene, without having to refocus: something not possible with past soft-focus lenses.

Below is the computer-translated text from the patent detailing how the soft-focus module would work:

A second arrangement state by which said 1st focus group and said 2nd focus group are arranged so that a second aberration amount which will be in a focusing state in the aforementioned predetermined object distance, and is different from said first aberration amount may be generated.

Regardless of whether or not one of these lens designs ever makes it to market, this isn't the first time a soft-focus lens has been made. In 1935, Leitz created the Thambar 90mm F2.2, a classic Leica lens renowned for its dream-like aesthetic. In fact, Leica released a modernized M-mount version of the Thambar 90mm F2.2 late last year as well.

As with all patents and patent applications, this design may never leave the metaphorical paper. But it's interesting nonetheless.