Contax N Lens to Sony E-mount T Speed Booster ULTRA 0.71x Adapter

Key Features

Owners of legendary Carl Zeiss optics in Contax N-Mount have long demanded a trusted migration path to mirrorless cameras. With the advent of Metabones® Contax N-Mount to Sony E-Mount Smart Adapter, the longing is over.

Built upon the foundation of Metabones' past success, phase-detection autofocus on A9, A7R Mark III, A7 Mark III, A7R Mark II, A7 Mark II, A6500 and A6300 not only offers pinpoint accuracy but also AF speed significantly surpassing the original Contax N series AF cameras. (Tailored to single-lens reflex cameras with a traditional phase-detection autofocus system, Contax N lenses are not compatible with contrast-detection autofocus mirrorless cameras such as A7S Mark II.)

Get a glimpse of the ergonomic experience of the original Contax N1 camera by using the lens' own aperture ring in aperture priority and manual exposure modes on A9, A7 series, A6500 and A6300. Fully automatic exposure and shutter priority are also available.

A customizable button on the adapter can be assigned to more than 50 different functions on an A9, A7 series, A6500 or A6300 camera, including depth-of-field preview. Putting that button on the hand-grip side would have matched a genuine Contax N camera, but since that would have been next to Sony's lens release button, we opted to place this customizable button on the other side of the adapter instead, right where the thumb of your left hand is.

The workmanship and attention to detail are evident from the signature Metabones design and the two electrical contacts carrying power, which are thicker in the same way as a genuine Contax N series autofocus camera. The inside of the adapter is flocked with felt to minimize internal reflection. A tripod foot compatible with Arca-Swiss style quick release is included.

Metabones has a proven track record of firmware stability and timely firmware support. Firmware is user-upgradable via the adapter's micro USB port.

Metabones adapters relay distance information from the lens to the camera body to enable full 5-axis in-body image stabilization of the A9, A7 Mark III series, A7 Mark II series and A6500. (The Contax 645 Makro-Planar 4/120 lens does not report distance information and supports only 3-axis in-body image stabilization.)

Contax made history by offering the world's first full-frame digital camera, Contax N-Digital, in 2002. All Contax products had been discontinued by 2005, leaving some of the finest autofocus optics ever made in search of a successor. None of these lenses feature optical image stabilization, and this is where the 5-axis in-body image stabilization (SteadyShot INSIDE) of Sony A9, A7 Mark III series, A7 Mark II series and A6500 comes in as a much-needed complement.

The heritage lives on, with the very same Carl Zeiss lenses from the dawn of full-frame digital photography now leveraging the latest and greatest mirrorless camera features and poised to benefit from further technological advances in the future.

Speed Booster® ULTRA

Speed Booster® ULTRA uses an advanced 5-element/4-group optical design by Caldwell Photographic Inc., incorporating ultra-high index tantalum-based optical glass to achieve extraordinary optical performance with improved corner sharpness, distortion and reduced vignetting. Speed Booster® ULTRA has a magnification of 0.71x,  effectively reducing the crop factor of APS-C cameras from 1.5x to 1.07x. The Speed Booster® ULTRA design makes very effective use of exotic materials at the furthest limit of glassmaking technology, and as a result is well corrected for use with virtually all full-frame SLR lenses regardless of exit pupil distance. Thus, the Speed Booster ULTRA performs extremely well with professional-grade f/2.8 zoom lenses such as the Carl Zeiss Vario-Sonnar T*2,8/17-35. Similarly, high-speed fixed focal length lenses such as the Carl Zeiss Planar T* 1,4/50 and Carl Zeiss Planar T* 1,4/85 will be transformed into f/1.0 lenses with excellent contrast and resolution from the center all the way to the edges of the image. Like all Metabones Speed Boosters, the Speed Booster ULTRA is optimized to fully account for the camera’s filter stack located near the sensor surface. This is especially critical at the extremely large apertures made possible by Speed Booster technology. As a result of this careful optimization, the complete range of Contax N and Contax 645 lenses will function flawlessly when adapted to Sony E-mount APS-C format camera bodies. (Speed Booster ULTRA cannot be used to adapt a Contax 645 lens to a full-frame E-Mount camera such as the A9 and the A7 series.)


Product name: Metabones Contax N Lens to Sony E-mount Smart Adapter (MB-CN-E-BT1)

Dimension: 31.4 x 72.3 x 76.0mm

Weight: 207g

Color: Black Satin exterior; Black Matte interior

Electronic Features:

  • AF with Contax N mount lens (refer to the above supported lenses list for details)
  • 5-axis in-body image stabilization on A9, A7 Mark III series, A7 Mark II series and A6500.

Optical Features:

  • Advanced 5-element/4-group optical design incorporating ultra-high index tantalum-based optical glass by Caldwell Photographic in the USA (patent granted).
  • Increase maximum aperture by 1 stop.
  • Increase MTF.
  • Makes lens 0.71x wider.
  • Felt material flocked inside to reduce internal reflections.

Rubber gasket protects E-mount connection from dust and moisture.

Tripod Mount: Detachable and compatible with Arca Swiss, Markins and Photo Clam ball heads.


Tested Camera Bodies:

  • PDAF support*

    A1, A9 II, A9, A7R IV, A7 IV, A7R III, A7S III, A7III, A7R II, A7II, A6700, A6600, A6500, A6400, A6300

    * Contax N lenses are not compatible with contrast-detection autofocus mirrorless cameras - no AF support for E-mount cameras other than the models listed above.

  • IBIS support (full 5-axis in-body image stabilization) **

    A9 II, A9, A7R IV, A7 IV,  A7R III, A7 III, A7RII, A7II, A7SIII, A6700, A6600, A6500

    ** Contax 645 Makro-Planar 4/120 lens does not report distance information and supports only 3-axis in-body image stabilization

Lens Compatibility Chart

When using the Contax N to E Speed Booster ULTRA on a full-frame E-Mount camera such as the A9 and the A7 series, it is required to be set to APS-C mode or Auto sensor size. The Speed Booster ULTRA is designed for APS-C format.

The following Contax N mount lenses are supported and tested:

In addition, the following Contax 645 lenses, adapted to Contax N-mount by Contax NAM-1 adapter (not included), are supported and tested

Vario-Sonnar T* 2,8/17-35

Vario-Sonnar T* 3,5-4,5/24-85

Vario-Sonnar T* 3,5-5,6/28-80

Vario-Sonnar T* 3,5-4,5/70-200

Vario-Sonnar T* 4-5,6/70-300

Planar T* 1,4/50

Planar T* 1,4/85

Makro-Sonnar T* 2,8/100

Apo-Teletessar T* 4/400

Vario-Sonnar T* 4,5/45-90

Distagon T* 3,5/35

Distagon T* 2,8/45

Distagon T* 3,5/55

Planar T* 2/80

Apo-Makro-Planar T* 4/120

Sonnar T* 2,8/140

Sonnar T* 4/210

Apo-Teletessar T* 4/350

Mutar 1.4x T*


Why Metabones®?

Since its inception, Metabones has been designing and manufacturing lens adapters recognized among professionals and enthusiasts as leaders in design and workmanship.

Contrary to the popular trend of other factories using an aluminum ring painted black on the camera-body-side, we instead take no short-cut but use precision-machined brass with chromium plating on both the camera-body and the lens sides of our adapters, in order to ensure smooth mounting, great appearance, and durability. The lens side of the adapter features a strong leaf-spring structure, strengthening the adapter-lens connection and ensuring tightness of the lens in order to reduce wear and prevent focus errors and optical alignment issues from appearing.

Metabones uses matte-black treatment to keep internal reflection to a minimum in order to maintain the maximum optical quality possible with the lens.

All Metabones Adapters follow this tradition of uncompromising precision, robust build quality and outstanding finish. Our new Smart AdapterTM series of products add industry-leading electronic interfacing technology from Canada, with true electronic control of the lens' aperture directly from the camera body.


Our Smart AdapterTM  series adapters have the following additional features