ARRI's LPL Mount

High-precision mechanics

Animation Header_LPL Mount
A universal mount for digital capture

The LPL mount (“Large Positive Lock”) is the first universal lens mount designed specifically for digital capture. The PL mount has a number of limitations when working with digital sensors and modern lenses, and the LPL mount specifically addresses those limitations.

Entering new dimensions

The LPL mount has a wider diameter (62 mm vs. 54 mm) and a shorter flange focal distance (44 mm vs. 52 mm) than the original ARRI-invented PL mount. These characteristics help optical designers eliminate disturbing optical artifacts.

To guarantee the highest performance across the image, light should strike the sensor at as close to perpendicular as possible. A lens that delivers such an image is called “telecentric.” This can only be achieved if a lens’s rear element is as large as the sensor that it illuminates, which is more often the case with the LPL mount.

Light striking at steep angles may not be full detected by the sensor, or lead to photo site “crosstalk” when absorbed by the wrong photo site. Also, digital cameras usually incorporate a filter package in front of the sensor, which contains an optical low-pass filter as well as spectral filters. At all points other than the center of the frame, light from a non-telecentric lens passes through this filter package at extreme angles, which causesaberrations at the frame edges. Telecentric optical designs, made possible by the LPL mount, eliminate these effects.

The shorter flange focal distance of the LPL mount aids optical designers in reducing image defects such asdistortion, spherical aberration, field curvature, and chromatic aberrations in high-speed lenses (with a low T-stop number).

The LPL mount can accommodate all common digital sensor sizes, from ALEXA Mini to ALEXA 65, and allows for the design of smaller, lighter, and faster lenses with enhanced optical properties. Any lens can be used on any camera, as the lens mount will never interfere with sensor coverage.

A proven mechanical design

The original ARRI PL mount became the film industry standard due to its simplicity, robustness, and reliability. The PL mount was designed around the 35 mm film frame at a time when most cinematographers did not work in larger formats, and it leaves room for a spinning mechanical shutter that no longer exists in digital cameras. The LPL mount is a response to the fact that modern cinematographers are no longer limited to one imaging format, and the optical tolerances for high-quality digital capture exceed those of film. 

LPL mounts are equipped with blue locking levers, so they can easily be distinguished from the black locking levers of the PL-to-LPL adapter. 

Towards a universal standard

ARRI shares LPL specifications openly and at no charge in order to establish it as the new standard interface between cameras and lenses. ARRI LPL lens mounts are available for ALEXA LF, ALEXA Classic/XT/SXT, ALEXA Mini LF, ALEXA Mini, AMIRA, and ALEXA 65 cameras. In addition, third parties offer LPL lens mounts for non-ARRI cameras, director's viewfinders, and lens testing tools.

The robust and easy-to-use PL-to-LPL adapter offers backwards compatibility with all PL mount lenses, withthe added benefit of increased sensor coverage over the standard PL mount.

Lens options for ARRI cameras with LPL Mount

Optimized for large-format lenses, the LPL lens mount fitted to ALEXA LF and ALEXA Mini LF cameras accepts ARRI Signature Primes and Zooms, ARRI Rental DNA LF and 65 format optics, and third-party LPL lenses. The PL-to-LPL adapter, which attaches securely to the LPL lens mount without tools, offers backwards compatibility with all PL mount lenses, be they Super 35 or full frame. LDS-2 or /i lens metadata is accessible via the LPL mount, and LDS-1 or /i via the PL-to-LPL adapter. ARRI’s Frame Line and Lens Illumination Tool, available in the Learn & Help/Tools section of the ARRI website, illustrates how much of the large-format sensor is covered by a given lens.

Other manufacturers, such as Panavision and Vantage, offer proprietary lens mounts for the ALEXA LF and ALEXA Mini LF cameras, to support their own lens ranges. Cinematographers therefore have an almost unlimited lens choice when shooting with ARRI large-format cameras.

Compatibility of Signature lenses

ARRI Signature Prime and Signature Zoom lenses are equipped with the LPL (Large Positive Locking) lens mount. A wider diameter and shorter flange focal depth allow LPL lenses to be small and lightweight, with a fast T-stop and pleasing bokeh—a combination of features that would not be possible with the old PL lens mount.

ARRI has shared LPL specifications openly and free-of-charge across the industry, establishing the LPL lens mount as a standard interface between cameras and lenses. ARRI LPL lens mounts are available for ALEXA 65, ALEXA LF, ALEXA Mini LF, ALEXA Classic/XT/SXT, ALEXA Mini and AMIRA cameras. In addition, third parties offer LPL lens mounts for cameras, director's viewfinders, and lens testing tools, so ARRI Signatures and other LPL lenses can be universally used.