New optical design: advanced 5-element/4-group optical design incorporating ultra-high index tanatalum-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 fullframe 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.
- 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”.
- Fast phase-detect AF is available only on A7RII and A7II. On other Sony cameras, contrast-detect AF with an EF mount lens is disappointingly slow and inadequate for all but static subjects,
- Even on A7RII and A7II, long telephoto lenses hunt more often and autofocus performance progressively deteriorates as focal length gets longer.
- On A7RII, the AF points near the center always work well, but those on the edges and in the corners may lose effectiveness when a fast lens or a telephoto lens is used.
- A7RII and A7II supports only contrast-detect AF during video recording. This means video AF speed may be unsatisfactory.
- During movie capture, autofocus needs to be manually activiated by half-pressing the shutter release button if subject moves to a different distance. Since contrast-detect autofocus speed is slow, there may be visible disruption in the resulting footage.
- With PXW-FS7, NEX-FS700 and NEX-FS100, autofocus works only in photo mode but disabled in movie capture mode.
- Continuous AF is not supported. (Does not work with contrast-detect AF and may have unsatisfactory performance with phase-detect AF of A7RII and A7II.)
- Eye AF is not supported.
- DMF mode (direct manual focus) is not supported.
- The first two 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 difficultly locking onto subjects which are very close to the nearest focusing distance of the lens.
- Autofocus accuracy depends heavily on the 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 NEX. 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.
- No support for lens corrections such as peripheral shading, CA and distortion.
- The EF-mount lens may make audible noises during iris changes and autofocus, wich may be picked up by the built-in microphone of the camera during video recording. Use of an external microphone is advised.
- Early Tamron VC lenses such as the 17-50/2.8 B005 may not be able to freely switch between OIS and IBIS because they may not report IS activity status. The latest generation Tamron VC lenses are fine.
- Some aftermarket battery grips may cause the aperture to change erraneously. This is a bug of 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.