As wide aperture lenses go, The Canon 65mm f/0.75 is probably one of the more ridiculous options one could consider. Initially this lens was designed for x-ray machines, but photographers can now adapt it to mirrorless cameras.
When you think of the best lenses for bokeh, chances are that you're probably thinking of something like the Sigma 105mm f/1.4 Art lens. This huge, behemoth of a lens can not only produce incredibly sharp results, but also some of the most bokeh-filled backgrounds possible. However, if all you're after is some mind-bending bokeh, this x-ray lens from Canon be exactly what you're looking for.
• Read more: What is bokeh?
In a recent video (below) from Mathieu Stern, he demonstrates how he adapted the Canon 65mm f/0.75 – one of the fastest lenses you can find – to his Sony mirrorless camera. The lens isn't designed to be mounted on conventional cameras, so instead, Stern devised a way for the lens to project its image circle on to the sensor without actually being connected. The results are interesting to say the least.
The size and weight of the lens does add to the complexity on how it can be used. At 2kg it's no lightweight, and the depth of field it produces is so shallow that Stern describes it as being a nightmare to shoot with. Adding on to that is the fact that it has no aperture blades to help you get more depth of field if or when required.
Nonetheless, the results are definitely unique and not really possible to achieve with most lenses currently on the market. Detail and clarity aren't really what the lens produces, but the bokeh balls are huge – and that's what counts here. In the few portraits that Stern somehow managed to get correctly in focus, the background completely melts away and it produces an almost dreamlike look.
This lens is probably not for everyone, however it's interesting to see the kind of results it can produce. If you want to get super shallow depth of field much more easily (and natively), though, we recommend going for a modern super-fast optic like the Mitakon Speedmaster 50mm f/0.95 or, if money is no object, the Nikkor Z 58mm f/0.95 Noct.