Felt material flocked inside to reduce internal reflection.
Electronic
Fast contrast-detection AF on all E-mount cameras (except AF-S/DMF with Sony A9).
Pure phase-detection autofocus support on A9, A7RII, A7II, A6500 and A6300 (the fastest).
Supports 5-axis in-body image stabilization of A7II, A7RII and A7SII. (Distance information from lens required; 3-axis IBIS if lens does not transmit distance information.)
Powered by camera body. No external power source required.
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.
Limitations
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".