Canon EF-S — flange distance, protocol, and adapter compatibility
APS-C-only variant of EF with a protruding rear element that physically prevents mounting on full-frame EF bodies. Shares EF's flange distance and electronic protocol — every EF-S lens behaves like an EF lens on compatible bodies. Discontinued in 2018 as Canon moved its APS-C line to EF-M and then RF-S.
Mount specifications
Flange focal distance
44 mm
Throat diameter
54 mm
Electronic protocol
Canon EF
Supported formats
APS-C
Manufacturer
Canon
Introduced
2003 (discontinued)
Status
Discontinued
Canon EF-S on the flange-distance axis
Canon EF-S sits at 44 mm — highlighted in orange below. The flange-distance gap between the mirrorless and SLR clusters is the room a mechanical adapter occupies; that gap is why almost every SLR lens adapts onto every mirrorless body, and why the reverse is mechanically impossible.
EF-S is electronically identical to EF, so the Fringer EF-NZ II drives AF, electronic aperture and IS on EF-S lenses exactly as on EF.
EF-S's APS-C image circle covers only APS-C — on a full-frame Z body (Z6 III / Z8 / Z9) the camera shoots in 1.5× DX crop mode or vignettes; native coverage only on APS-C Z bodies (Z50 / Zfc / Z30).
EF-S is electronically identical to EF, so smart EF-E adapters drive AF, IS and electronic aperture on EF-S lenses exactly as on EF — STM EF-S lenses focus reliably for stills.
EF-S's APS-C image circle covers an APS-C E body (a6700, FX30, ZV-E10 II) natively; on a full-frame α the camera must stay in APS-C crop mode or the corners vignette.
Fringer drives phase-detect AF, IS and electronic aperture on EF-S lenses just as on EF — EF-S behaves as native EF electronically.
Unlike full-frame EF glass (which is 1.5× cropped on X-Trans), an EF-S lens's APS-C image circle matches the X-mount APS-C sensor exactly — no coverage wasted, no crop penalty.
Electronics pass through (AF on a curated lens list, electronic aperture), but an EF-S lens's APS-C image circle is far smaller than the 44×33 mm GFX sensor — usable only in a heavy central crop, so this pairing is of limited practical value.
Prefer full-frame EF glass for GFX; EF-S is mechanically possible but optically wasteful here.
Viltrox EF-M2 II (0.71× focal reducer, electronic)
Metabones EF-MFT Speed Booster / Smart Adapter
EF-S is electronically EF, so the same smart EF-MFT adapters pass aperture / IS and drive contrast-detect AF on EF-S glass (partial — usable but slower than native).
The Micro Four Thirds sensor is smaller than EF-S's APS-C image circle, so coverage is never an issue; a focal-reducer variant restores reach and a stop of light.
The MC-21 accepts EF and EF-S alike and passes AF, IS and electronic aperture; Sigma's own EF lenses have the widest supported list.
EF-S's APS-C image circle is native on an APS-C L body (Leica CL / TL2); on a full-frame L body (SL2, Panasonic S5 II) stay in APS-C crop mode to avoid vignetting.
Flange clearance is only 0.0 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Speed Booster equivalence calculator
Plug in any Canon EF-S lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Canon EF (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top.
Effective focal length
35.5 mm
50.0 mm × 0.71 on the reducer.
Effective aperture
f/1.28
0.99 stops brighter than f/1.80.
Full-frame equiv. angle of view
53.3 mm
35.5 mm × 1.5× (APS-C sensor crop).
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.
Flange clearance is only -2.5 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Speed Booster equivalence calculator
Plug in any Canon EF-S lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Nikon F (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top.
Effective focal length
35.5 mm
50.0 mm × 0.71 on the reducer.
Effective aperture
f/1.28
0.99 stops brighter than f/1.80.
Full-frame equiv. angle of view
53.3 mm
35.5 mm × 1.5× (APS-C sensor crop).
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.
Flange clearance is only -0.5 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Speed Booster equivalence calculator
Plug in any Canon EF-S lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Sony A / Minolta A (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top.
Effective focal length
35.5 mm
50.0 mm × 0.71 on the reducer.
Effective aperture
f/1.28
0.99 stops brighter than f/1.80.
Full-frame equiv. angle of view
53.3 mm
35.5 mm × 1.5× (APS-C sensor crop).
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.
Flange clearance is only -1.5 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Speed Booster equivalence calculator
Plug in any Canon EF-S lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a M42 (Pentax / Praktica screw mount) (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top.
Effective focal length
35.5 mm
50.0 mm × 0.71 on the reducer.
Effective aperture
f/1.28
0.99 stops brighter than f/1.80.
Full-frame equiv. angle of view
53.3 mm
35.5 mm × 1.5× (APS-C sensor crop).
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.
Flange clearance is only -1.5 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Speed Booster equivalence calculator
Plug in any Canon EF-S lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Pentax K (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top.
Effective focal length
35.5 mm
50.0 mm × 0.71 on the reducer.
Effective aperture
f/1.28
0.99 stops brighter than f/1.80.
Full-frame equiv. angle of view
53.3 mm
35.5 mm × 1.5× (APS-C sensor crop).
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.
Flange clearance is only -8.0 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Speed Booster equivalence calculator
Plug in any Canon EF-S lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a PL (Positive Lock) (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top.
Effective focal length
35.5 mm
50.0 mm × 0.71 on the reducer.
Effective aperture
f/1.28
0.99 stops brighter than f/1.80.
Full-frame equiv. angle of view
53.3 mm
35.5 mm × 1.5× (APS-C sensor crop).
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.
Flange clearance is only 0.0 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Speed Booster equivalence calculator
Plug in any Canon EF-S lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Canon EF (cine) (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top.
Effective focal length
35.5 mm
50.0 mm × 0.71 on the reducer.
Effective aperture
f/1.28
0.99 stops brighter than f/1.80.
Full-frame equiv. angle of view
53.3 mm
35.5 mm × 1.5× (APS-C sensor crop).
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.
Flange clearance is only -0.7 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Speed Booster equivalence calculator
Plug in any Canon EF-S lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Exakta (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top.
Effective focal length
35.5 mm
50.0 mm × 0.71 on the reducer.
Effective aperture
f/1.28
0.99 stops brighter than f/1.80.
Full-frame equiv. angle of view
53.3 mm
35.5 mm × 1.5× (APS-C sensor crop).
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.
Flange clearance is only -11.0 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Speed Booster equivalence calculator
Plug in any Canon EF-S lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a T-mount (T2) (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top.
Effective focal length
35.5 mm
50.0 mm × 0.71 on the reducer.
Effective aperture
f/1.28
0.99 stops brighter than f/1.80.
Full-frame equiv. angle of view
53.3 mm
35.5 mm × 1.5× (APS-C sensor crop).
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.
Flange clearance is only -0.4 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Speed Booster equivalence calculator
Plug in any Canon EF-S lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Praktica B (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top.
Effective focal length
35.5 mm
50.0 mm × 0.71 on the reducer.
Effective aperture
f/1.28
0.99 stops brighter than f/1.80.
Full-frame equiv. angle of view
53.3 mm
35.5 mm × 1.5× (APS-C sensor crop).
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.
Flange clearance is only 0.5 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Speed Booster equivalence calculator
Plug in any Canon EF-S lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Minolta SR / MC / MD (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top.
Effective focal length
35.5 mm
50.0 mm × 0.71 on the reducer.
Effective aperture
f/1.28
0.99 stops brighter than f/1.80.
Full-frame equiv. angle of view
53.3 mm
35.5 mm × 1.5× (APS-C sensor crop).
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.
Flange clearance is only -2.0 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Speed Booster equivalence calculator
Plug in any Canon EF-S lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Olympus OM (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top.
Effective focal length
35.5 mm
50.0 mm × 0.71 on the reducer.
Effective aperture
f/1.28
0.99 stops brighter than f/1.80.
Full-frame equiv. angle of view
53.3 mm
35.5 mm × 1.5× (APS-C sensor crop).
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.
Flange clearance is only -1.5 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Speed Booster equivalence calculator
Plug in any Canon EF-S lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Contax/Yashica (C/Y) (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top.
Effective focal length
35.5 mm
50.0 mm × 0.71 on the reducer.
Effective aperture
f/1.28
0.99 stops brighter than f/1.80.
Full-frame equiv. angle of view
53.3 mm
35.5 mm × 1.5× (APS-C sensor crop).
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.
Adapting other lenses onto a Canon EF-S body
You own a Canon EF-S body and want to mount glass from other systems. Mirrorless-lens-onto-DSLR-body combinations are omitted (rear element collides with the mirror box).
Flange clearance is only 0.0 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Flange clearance is only -2.0 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Flange clearance is only 0.5 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Flange clearance is only 1.5 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Flange clearance is only 1.5 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Flange clearance is only 0.0 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Flange clearance is only 0.7 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Flange clearance is only 0.4 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Flange clearance is only -3.5 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Flange clearance is only -0.5 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Flange clearance is only 1.5 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required.
Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
No — Canon EF-S lenses have a protruding rear element that physically prevents mounting on full-frame EF bodies (5D series, 6D series, 1D X, 1Ds) and would damage the mirror box if forced. EF-S only fits APS-C EF bodies (Rebel / xxxD / xxD / 7D). On RF, the EF-EOS R adapter does accept EF-S; the body crops automatically to APS-C.
Is Canon EF-S still being produced in 2026?
No — Canon discontinued the EF-S line in 2018 alongside the broader retirement of EF DSLRs, replacing it first with EF-M (also discontinued in 2023) and now with RF-S for APS-C mirrorless. Existing EF-S lenses remain fully usable on every APS-C EF DSLR and on RF bodies via the EF-EOS R adapter; the secondary market is well-supplied and consumer-zoom prices are low.
Will an EF-S lens autofocus on a Canon RF body through the EF-EOS R adapter?
Yes — EF-S behaves identically to EF over the adapter. AF, IS, and electronic aperture all work on every EF-S lens through every Canon EF-EOS R adapter variant. The RF body crops to APS-C automatically when it detects the EF-S protrusion via the adapter's pass-through electronics; manual override is available in the body menu.