Enabling full use of Contax N-mount lenses with APS-C-format Sony E-mount mirrorless cameras, this Metabones Speed Booster ULTRA 0.71x Adapter permits working with these classic, optically refined lenses with a modern camera system. The unique Speed Booster design incorporates a five-element, four-group optical design, using ultra-high refractive index tantalum-based glass, to maintain high optical quality as well as effectively eliminate the crop factor associated with the APS-C format and increase the mounted lens's maximum aperture by one stop. This optical design widens the lens's field of view by 0.71x, which reduces the effective APS-C crop factor from 1.5x to 1.07x. Additionally, the use of high refractive index glass helps to retain overall high sharpness from edge to edge and reduce vignetting and distortion. Additionally, the adapter affords full autofocus support when used with a camera offering phase-detection autofocus, and it also maintains five-axis image stabilization from select camera bodies to help control camera shake.
A programmable function button on the side of the adapter can be used to adjust more than 50 different functions on the camera body, including depth of field preview, for intuitive use. Two electrical contacts carry power from the camera body and a 10-pin contact transfers Exif data between the lens and the camera body. In regard to its physical design, chromium-plated brass mounts are featured on both the camera and lens sides; rubber gaskets help prevent dust and moisture from entering; a satin finish mimics the feel of the lens itself; and the interior of the adapter is felt-flocked to reduce glare or internal reflections. A removable tripod foot is also featured, and has a 1/4"-20 mount and is Arca-type compatible for flexible use. Additionally, an integrated micro-USB port permits easy installation of firmware updates.
Contax N lenses are not compatible with contrast-detection autofocus; autofocus is only supported by E-mount cameras featuring phase-detection AF:
- Sony Alpha a9, a7R III, a7 III, a7R II, a7 II, a6500, and a6300
Five-axis in-body image stabilization is supported with:
- Sony Alpha a9, a7R III, a7 III, a7R II, a7 II, a7S II, and a6500
- Contax N-mount lenses
- Contax 645 lenses when adapted to Contax N mount via the Contax NAM-1 adapter (the Contax 645 Apo-Makro-Planar T* 120mm f/4 lens does not report distance information and only supports three-axis image stabilization). Contax 645 lenses cannot be adapted to full-frame E-mount cameras