How does the Kipon Baveyes EF-FE compare optically to the Metabones Speed Booster ULTRA?

Comparable — both use Brian Caldwell-designed 0.7× reduction optics under the same patent family, with Kipon and Metabones each holding the licence for different lens-to-body routes. Corner sharpness, light gain (~1 stop), and focal-length reduction (0.7×) are equivalent on Sigma Global Vision Art and Canon L USM glass. Mechanical fit and electronics execution differ slightly — Metabones has tighter PDAF tracking on Sony bodies; Kipon costs $300-400 less.

Will it autofocus on a full-frame Sony body?

Mechanically the Baveyes EF-FE 0.7× covers the APS-C sensor format only — its rear optical element delivers an APS-C-sized image circle. On a full-frame Sony body (A7 series, A1, A9) you can mount it, but the body must be set to APS-C crop mode (or you'll see hard vignetting from the reduced image circle). For full-frame EF on full-frame Sony without reduction, use the plain Kipon EF-NEX or any non-Speed-Booster EF-on-Sony adapter.

Does it work with EF-S APS-C Canon lenses?

Mechanically yes but optically pointless — EF-S lenses already cover the APS-C circle natively; applying a 0.7× reduction shrinks them below APS-C, vignetting at all focal lengths. Speed Boosters are for adapting full-frame-image-circle lenses (EF, Sigma DG, Tamron Di) onto smaller sensors. Use a plain EF-S → Sony E mechanical / electronic adapter for EF-S lenses.

Kipon · Canon EF → Sony E adapter

Kipon Baveyes EF-FE 0.7x — Canon EF → Sony E adapter

0.7× focal reducer (Brian Caldwell optics under Caldwell Photographic licence — same patented IP family as Metabones' Speed Booster ULTRA) for adapting EF full-frame lenses to Sony APS-C bodies (a6000-series, FX30). ~1 stop wider effective aperture and 0.7× focal-length factor on top of the APS-C crop.

At a glance

Vendor: Kipon
Release year: 2017
Body-side contacts: 9 pins
Flags: firmware-updatableweather-sealed —requires glass

What this adapter preserves

Compatibility for Canon EF lens on a Sony E body (computed from the lensmount dataset — open the Canon EF to Sony E adapter page for the full verdict, flange clearance, and adapter caveats).

Focus: Full AF
IS: IS / IBIS preserved
Aperture: Electronic aperture
Infinity focus: Reaches infinity

What it does

Electronic aperture and basic AF preserved on EF USM / STM lenses. AF is contrast-detect-biased on PDAF Sony bodies — slower than Sigma MC-11 / Metabones EF-E V on tracking, but typically $300-400 cheaper than the equivalent Metabones Speed Booster.

Lands at 60-80% the price of Metabones Speed Booster ULTRA EF-E with comparable optical performance on Sigma Art / Canon L USM glass.

Firmware history

v1.02017
- Initial release — Canon EF / EF-S onto Sony E APS-C bodies with 0.7× optical reduction and electronic aperture / AF pass-through
v2.02020
- PDAF refinements on Sony a6400 / a6600
- Additional Canon EF L USM lens compatibility entries

Approximate milestones — verify against the Kipon firmware page for the authoritative changelog.

Try your lens through this focal reducer

Pick a lens focal length, max aperture, target body sensor format, and reducer family below — the calc returns the effective focal length, effective f-number, and full-frame equivalent angle of view on that body. Both focal length and f-number scale by the reducer ratio (so the lens always gets two stops faster, distributed as −2·log₂(ratio) stops).

Speed Booster equivalence calculator

Plug in any Canon EF lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a APS-C body of your choice, plus the full-frame equivalent angle of view after the body's crop stacks on top.

Lens focal length (mm)Max aperture (f/N)Body sensor formatFocal-reducer family

Effective focal length: 35.5 mm
Effective aperture: f/1.28
Full-frame equiv. angle of view: 53.3 mm

A focal reducer concentrates the lens's image circle, so both focal length and f-number scale by the same ratio (stops gained = −2 · log₂(ratio)). The body's crop factor still applies on top — the full-frame-equivalent angle-of-view multiplier is ratio × body crop. Calculator is informational; verify against the adapter vendor's per-lens compatibility chart before purchase.

Common questions

How does the Kipon Baveyes EF-FE compare optically to the Metabones Speed Booster ULTRA?: Comparable — both use Brian Caldwell-designed 0.7× reduction optics under the same patent family, with Kipon and Metabones each holding the licence for different lens-to-body routes. Corner sharpness, light gain (~1 stop), and focal-length reduction (0.7×) are equivalent on Sigma Global Vision Art and Canon L USM glass. Mechanical fit and electronics execution differ slightly — Metabones has tighter PDAF tracking on Sony bodies; Kipon costs $300-400 less.
Will it autofocus on a full-frame Sony body?: Mechanically the Baveyes EF-FE 0.7× covers the APS-C sensor format only — its rear optical element delivers an APS-C-sized image circle. On a full-frame Sony body (A7 series, A1, A9) you can mount it, but the body must be set to APS-C crop mode (or you'll see hard vignetting from the reduced image circle). For full-frame EF on full-frame Sony without reduction, use the plain Kipon EF-NEX or any non-Speed-Booster EF-on-Sony adapter.
Does it work with EF-S APS-C Canon lenses?: Mechanically yes but optically pointless — EF-S lenses already cover the APS-C circle natively; applying a 0.7× reduction shrinks them below APS-C, vignetting at all focal lengths. Speed Boosters are for adapting full-frame-image-circle lenses (EF, Sigma DG, Tamron Di) onto smaller sensors. Use a plain EF-S → Sony E mechanical / electronic adapter for EF-S lenses.

Head-to-head comparisons

Kipon Baveyes EF-FE 0.7x vs Metabones Speed Booster ULTRA 0.71× EF-E

Mounts on either side

Lens side

Canon EF

Flange 44 mm · Canon

Open mount page →

Body side

Sony E (incl. FE)

Flange 18 mm · Sony

Open mount page →

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