New optical design:  advanced 5-element/4-group optical design incorporating ultra-high index tantalum-based optical glass to achieve extraordinary optical performance with improved corner sharpness, distortion and reduced vignetting.

Like the revolutionary original Metabones Speed Booster announced in January 2013, the Speed Booster ULTRA has a magnification of 0.71x, and so it effectively reduces the crop factor of mirrorless cameras with DX-sized sensors, such as Sony E-mount and Fuji X-mount cameras, from 1.5x to 1.07x.  However, the new 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 24-70mm f/2.8 and 70-200mm f/2.8 zooms by Canon and Nikon to produce 17-50mm f/2.0 and 50-142mm f/2.0 high-speed zooms, respectively.  Similarly, high-speed fixed focal length lenses such as a 50mm f/1.2 will be transformed into a 35.5mm f/0.9 lens with excellent contrast and resolution from the center all the way to the edges of the image.

Metabones Exclusive

• Patented 5-element/4-group optical design incorporating ultra-high index tantalum-based optical glass by Caldwell Photographic in the USA.
• If both your lens supports optical image stabilization (OIS) and your camera supports sensor-shift, in-body image stabilization (IBIS), the choice is yours on which one to use, or have both of them work in harmony.
• Smooth iris support with the latest Canon (2009+), Tamron (SP series 2013+) and Sigma (2016+) lenses.
• Custom function button (called Focus Hold button) assignable to more than 50 functions, such as Aperture Preview and Eye-AF, on A9, A7 series, A6500 and A6300.
• Dedicated switch controls in-body image stabilization (IBIS) on Sony cameras equipped with SteadyShot INSIDE.
• Compatible with Sony FS7 Mark II camera.
• Cinema EOS lens (CN-E) support, including power zoom, AF and auto iris.
• Rubber gasket protects E-mount connection from dust and moisture.
• Detachable tripod foot, compatible with Arca Swiss, Markins and Photo Clam ball heads.

Optical/Mechanical

• Increase maximum aperture by 1 stop.
• Increase MTF.
• Makes lens 0.71x wider.
• Felt material flocked inside to reduce internal reflection.

Electronic

• AF-C tracking during high-speed drive at up to 10fps on Sony A9, A7III and A7RIV.
• Fast contrast-detection AF on all E-mount cameras with most lenses.
• Pure phase-detection autofocus support on A9, A7III, A7RIII, A7RII, A7II, A6600, A6500, A6400, A6300 and A6100.
• Supports 5-axis in-body image stabilization of A7RIV, A7III, A7RIII, A7II, A7RII and A7SII. (Distance information from lens required; 3-axis IBIS if the lens does not transmit distance information.)
• Powered by camera body. No external power source required.
• LED indicator shows operation mode, OIS (optical image stabilization) activity and communication status.
• Efficient switched-mode power supply.
• Supports image stabilization (IS) lenses.
• Supports electronic manual focusing (e.g. EF 85/1.2L II and discontinued EF 50/1.0L)
• EXIF support (focal length, aperture, lens name)
• Distance and zoom display on VG and FS series camcorders, A9, A7 series, A6500 and A6300 (lens with distance information support required).
• Auto magnify (lens with distance information support required)
• Auto "APS-C Size Capture" on full-frame cameras with Canon EF-S lenses and many third-party DX lenses.
   

Optical/mechanical

• Full-frame lens required. EF-S/DX/DC/Di II lenses are NOT supported.
• Speed Booster ULTRA is designed to cover an APS-C image circle which is not big enough to cover a full-size 36mm x 24mm sensor. On a full frame camera body (A7 series, NEX-VG900) the camera needs to have "APS-C/Super 35mm" set to either "Auto" or "On".

Autofocus

• AF-C is supported on A9, A9, A7RIV, A7RIII, A7SIII, A7IV, A7III, A7RII, A7II, A6600, A6500, A6400, A6300 and A6100 only.
• Continuous video AF is functional in Advanced mode only, but performance may be unsatisfactory.
• On Sony A9, only phase-detection autofocus is supported. Contrast-detection autofocus may not work satisfactorily.
• AF may not work if the maximum aperture of the lens plus any EF Extender or other teleconverter attached is smaller than f/8 before boost or smaller than f/5.6 after boost.
• The first few autofocus attempts are used to calibrate the lens and as a result may not lock successfully on the target. Half-press the shutter release button again and autofocus will lock successfully.
• Autofocus may have difficulty locking onto subjects which are very close to the nearest focusing distance of the lens.
• Autofocus accuracy depends heavily on the design and working condition of the lens. Lenses with hidden problems which may not be apparent on Canon DSLRs will lead to inaccurate and unreliable autofocus on Sony. Typical problems of this kind that we have seen include an unsmooth/erratic autofocus mechanism (e.g. getting stuck intermittently at a certain focusing distance), a faulty/worn-out distance encoder or other faulty/worn-out internal sensors.

Other

• No support for lens corrections such as peripheral shading, CA and distortion.
• Use of Canon Cinema lenses such as CN-E 18-80mm T4.4 for still photography is not supported. (Functional, but slower than lenses designed for still photography.)
• Some EF-mount lenses may make audible noises during iris changes and autofocus, which may be picked up by the built-in microphone of the camera during video recording. Use of an external microphone is advised. Some of the recently-introduced Canon-brand lenses are very quiet, however.
• Early Tamron VC lenses such as the AF 28-300/3.5-6.3 XR Di VC LD Aspherical [IF] Macro (model A20), AF 18-270/3.5-6.3 Di II VC LD Aspherical [IF] MACRO (model B003), SP AF 17-50mm F/2.8 XR Di II VC LD Aspherical [IF] (model B005) may not be able to freely switch between OIS and IBIS because they may not report IS activity status. Later Tamron
• VC lenses equipped with USD or PZD focus motors are fine.
• Some aftermarket battery grips may cause the aperture to change erroneously. This is a bug in the aftermarket battery grip but NOT arising from the Metabones Speed Booster. Turn off the aftermarket battery grip or use a genuine Sony battery grip.