Metabones EF-E T CINE Speed Booster ULTRA 0.71x (MB_SPEF-E-BT3)

Optical Design

• Advanced 5-element/4-group optical design incorporating ultra-high index tantalum-based optical glass by Caldwell Photographic (USA) to achieve extraordinary optical performance.
• Improved corner sharpness, reduced distortion, and minimized vignetting.
• Magnification factor of 0.71x effectively reduces crop factor of DX-sized sensor mirrorless cameras (e.g., Sony E-mount, Fuji X-mount) from 1.5x to 1.07x.
• Well corrected for use with virtually all full-frame SLR lenses regardless of exit pupil distance.
• Transforms professional-grade f/2.8 zoom lenses (e.g., 24-70mm f/2.8, 70-200mm f/2.8) into faster high-speed zooms (e.g., 17-50mm f/2.0, 50-142mm f/2.0).
• Converts high-speed prime lenses such as 50mm f/1.2 into 35.5mm f/0.9 with excellent contrast and resolution across the frame.

Compatibility and Tested Camera Bodies

• Sony Alpha series: A7SII, A7RII, A7II, A7S, A7R, A7, A6500, A6300, A6000
• Sony Professional camcorders: PXW-FS7M2, PXW-FS5, PXW-FS7, NEX-FS700, NEX-FS100
• Sony NEX series camcorders and cameras: NEX-EA50, NEX-VG900, NEX-VG30, NEX-VG20, NEX-VG10, NEX-7, NEX-6, NEX-5R, NEX-5N, NEX-5, NEX-C3, NEX-3

Optical and Mechanical Features

• Increases maximum aperture by 1 stop.
• Improves Modulation Transfer Function (MTF) for sharper images.
• Makes attached lens 0.71x wider in focal length.
• New positive-lock Canon EF lens mount (patent pending) for secure attachment.
• Rubber gasket seals E-mount connection against dust and moisture.
• Felt flocking inside the opening reduces internal reflections.
• Detachable tripod foot compatible with Arca Swiss, Markins, and Photo Clam ball heads.
• Compatible with Sony FS7 Mark II camera.

Electronic Features

• Fast contrast-detect autofocus on all Sony E-mount cameras.
• Phase-detect autofocus support on A7RII, A7II, A6300, and A6500 models.
• Smooth iris control with Canon (2009+), Tamron (SP series 2013+), and Sigma (2016+) lenses.
• Supports 5-axis in-body image stabilization (IBIS) on A7II, A7RII, and A7SII (full 5-axis with lens distance info; 3-axis without).
• Dedicated switch to enable or disable IBIS.
• Status notification LED for operational feedback.
• Powered solely by the camera body; no external power required.
• Aperture control directly from the camera body.
• Custom function button assignable to over 50 functions on compatible Sony cameras.
• High-performance 32-bit processor with efficient power management.
• Supports image stabilization (IS) lenses and electronic manual focusing (e.g., EF 85mm f/1.2L II, EF 50mm f/1.0L discontinued).
• EXIF data support including focal length, aperture, and zoom range.
• Distance and zoom display on compatible Sony VG and FS series camcorders and A7 series cameras (lens must support distance info).
• Auto magnify function and automatic APS-C size capture on full-frame cameras.

Limitations

Optical/Mechanical

• Requires full-frame Canon EF lenses; EF-S, DX, DC, Di II lenses are not supported.
• Designed to cover APS-C image circle; on full-frame cameras, APS-C/Super 35mm mode must be set to Auto or On.
• Flocking material inside to reduce internal reflections.
• Tripod foot is detachable and compatible with common ball head systems.

Autofocus

• Continuous AF and video AF are not supported; performance may be unsatisfactory.
• AF may fail if lens maximum aperture plus any extender is smaller than f/8 before boost or smaller than f/5.6 after boost.
• Initial autofocus attempts calibrate the lens and may not lock; subsequent attempts typically succeed.
• AF may struggle with subjects near the lens's minimum focusing distance.
• AF accuracy depends on lens condition; lenses with internal issues may cause unreliable AF on Sony bodies.

Other

• No support for lens corrections such as peripheral shading, chromatic aberration, or distortion.
• EF lenses may produce audible iris and AF noises, which can be picked up by the camera microphone; external microphone recommended for video.
• Early Tamron VC lenses may not switch properly between optical and in-body stabilization; later models with USD or PZD motors are compatible.
• Some aftermarket battery grips may cause aperture control issues; use genuine Sony grips to avoid this.