Originally developed as a tool and technique to capture and project a wider aspect ratio on 35mm film, anamorphic lenses have become a favorite of cinematographers due to their unique characteristics in motion imagery. The ultra-wide rectangular aspect ratio, horizontal lens flares, and elliptical bokeh (out-of-focus areas of an image) now feel like a part of the movie experience, just like a bucket of popcorn and a liter of soda.
Anamorphic lenses are optical lenses that compress a wide field of view into a standard image area. They first appeared during World War I, where anamorphic lenses were used in tanks to provide a wider view. Later, this technology was introduced to the movie industry to fulfill the needs of shooting in a larger aspect ratio. So how do anamorphic lenses work? The term "anamorphic" comes from the Greek word meaning "reshaping." Compared to spherical lenses that project circular images onto the film or camera sensor, anamorphic lenses project elliptical images. This is because the optical elements squeeze more horizontal information from the scene. The captured image must then be horizontally stretched in post-production or by the projector to be viewed at the intended aspect ratio.
Traditionally, anamorphic lenses have a 2x compression, which means they capture twice the amount of horizontal information compared to spherical lenses. When stretched, a 2x anamorphic lens used with standard 35mm film produces a 2.39:1 aspect ratio, commonly known as CinemaScope or simply "Scope." The demand for wider aspect ratios drove the popularity of anamorphic lenses in the film industry. To achieve the same 2.39:1 aspect ratio with spherical lenses, the top and bottom of each frame would need to be cropped or "masked," sacrificing vertical resolution.
For digital cinematographers working in HD or 2K formats, cropping a 2K frame to achieve a 2.39:1 ratio would only yield a negligible 858 lines of vertical resolution. Anamorphic lenses offer a way to capture the 2.39:1 ratio without sacrificing resolution. However, due to the wider aspect ratio of digital sensors compared to 35mm film, a 2x anamorphic lens can produce a super-wide 3.55:1 ratio, while a 1.5x anamorphic lens can still achieve a 2.66:1 aspect ratio. To achieve the traditional "Scope" ratio with a 16:9 sensor, a 1.33x or 1.35x anamorphic lens is needed.
Whether you're seeking horizontal lens flares or aiming for the cinematic widescreen aspect ratio without losing vertical resolution, anamorphic lens options in the world of digital filmmaking are expanding new horizons.