The small the f-number, the larger the aperture and the more light a digital camera sensor receives. It also has a significant effect on the depth of field and sharpness of images. You may have noticed most commercial lens stop at around f/1.2. So why don't they go lower?
Many years ago, LA-based photographer Blair Bunting found himself in a position to not only acquire, but mount sub-f/1.0 lenses to his Canon 1D. Until recently, he held onto both his story -- and the photos -- only revealing them late last month:
...there was an industrial factory that did X-ray analysis that had gone under and surplussed it’s equipment. I called them up and offered to buy all their lenses for cheap as I intended to mount them to a Canon 1D ... The lenses that came in the box ranged from 110mm to 50mm and had aperture values of 1.1 to 0.50. Unfortunately, they were made for industrial X-ray machines, so mounting them would not be easy.
After some creative cutting -- and plumbing -- Bunting managed to get the lenses onto his camera. The resulting images can be found over at PetaPixel and Bunting's blog, but here are a couple of examples:
Interesting, for sure, but even with small subjects, getting a clear picture appears difficult. Certainly nothing you couldn't accomplish with a slower shot.
As Bunting states on his website, modifying the lens and taking the photos was simply an experiment, rather than an attempt to craft an array of super-fast lens for serious use. In fact, Bunting mentions he's since sold "most of the lenses [he] made".
So, unless you're chasing a specific (and blurry) look for your photos, you'll never have a need for a lens that below f/1.2. You're welcome to make your own however!