Adapting Canon EF and Nikon F Lenses: What Mounts, What Autofocuses, What Crops

This page covers two systems: Canon EF and EF-S lenses on RF bodies, and Nikon F lenses on Z bodies. After reading it you will know how to sort those lenses into three piles — full function, mounts but manual focus, and will not mount at all — and which markings on your own lens barrel decide which pile a lens lands in.

The short answer: there are three outcomes, not two

People ask "will it fit?" as a yes/no question. The manufacturers answer it as three separate questions, and a lens can pass one and fail another. Sorting your gear properly means checking all three.

1. Will it physically mount? Canon states that on the EOS R5, to attach EF or EF-S lenses you will need a mount adapter. Nikon states the FTZ II works with approximately 360 F-mount lenses. Both are same-brand cases using the maker's own adapter; this page makes no claim about other systems. Some lenses are excluded outright — Nikon names non-AI lenses, IX-NIKKOR, the TC-16A AF Teleconverter and a run of specific vintage optics, and warns that forcibly attaching any of them could damage the adapter or the lens.
2. Will it autofocus? This is where most F-mount lenses fall down, and it has nothing to do with whether they mount. Nikon publishes two figures: approximately 360 F-mount lenses mount and meter, and 94 of those — the AF-S, AF-P and AF-I types — keep full autofocus and auto-exposure. The remainder works out to approximately 266. That subtraction is this page's arithmetic, not a Nikon figure. Those lenses mount and meter but focus by hand, some with the electronic rangefinder confirming focus and some without. The table further down says which.
3. Will it use the whole sensor? A lens built for a smaller image circle can mount and autofocus perfectly and still force a crop. Canon says that with EF-S lenses on an EOS R5 the approximately 1.6x crop is set automatically and no other option is available. Nikon's equivalent: attaching a DX lens automatically selects the DX image area.

So the useful question is not "will it fit" but "which of these three do I lose". Work through your lenses one at a time.

The flat no we can cite

Canon's EOS R5 manual is unusually blunt on one point: the camera cannot be used with EF-M lenses. Not degraded, not manual-focus-only, not with a crop — it cannot be used. EF-M was Canon's mirrorless mount for its EOS M bodies. That sentence is a statement about one camera, so check your own body's manual under lens compatibility before assuming it generalises. None of the Canon pages read for this article documents an EF-M to RF adapter either. If your existing glass is EF-M and you are moving to an RF body, plan on the assumption that it will not come with you, and confirm against your own body's manual before spending anything.

Canon's EF and EF-S lenses are the opposite case: they adapt. Canon's own description of the EOS R system says mount adapters connect EF and EF-S lenses to EOS R cameras "with all functions intact". Read that as the manufacturer's claim about its own adapters, and read it narrowly, because Canon's other document contradicts it for EF-S. The EOS R5 manual states that with RF-S and EF-S lenses the 1.6x crop is applied automatically, that no other option is available, and that areas outside the cropped area are not recorded in RAW shooting. With RF or EF lenses the same manual offers a choice of full-frame, 1.6x crop or other aspect ratios. With EF-S there is no choice. Take "all functions intact" as covering the electronic connection between body and lens. It does not cover sensor coverage.

Why adapters work in one direction only

Flange focal distance is the gap between the lens mount ring and the sensor. A lens is computed to project a sharp image at a fixed distance behind its mount. If the new body places the sensor further back than the lens was computed for, the lens cannot reach infinity focus. Placing the sensor closer than designed is tolerable — the lens simply focuses past infinity before the ring reaches its stop — which is why a shortfall can be made up with a spacer.

A plain mount adapter is exactly that spacer: a ring of fixed thickness with no optics in it. That is the whole mechanism, and it explains the asymmetry. If the lens expects more distance than the new body provides, the adapter's thickness makes up the difference and the lens reaches infinity again. If the lens expects less distance than the body provides, there is no room, because you cannot make a gap smaller by inserting an object into it. That direction requires corrective optics inside the adapter, which changes the optical design, or it gives up infinity focus. This paragraph is an inference drawn from the published flange figures in the table below together with the fact that a passive adapter contains no lens elements. It is not a manufacturer statement.

That is why SLR glass adapts forward onto mirrorless bodies of the same brand, and why the reverse direction carries the costs just described rather than being a straight swap. Mirrorless mounts were designed with the mirror box gone, so their flange distances are short: Nikon publishes 16mm for Z, Canon 20mm for RF.

Nikon is explicit about why it chose those proportions: the 55mm inner diameter and short 16mm flange focal distance are what give its designers room for maximum apertures as wide as f/0.95. The geometry is a design decision, and it is the same geometry that leaves room behind an F-mount lens for a spacer.

What each lens type actually keeps: Nikon's own table

Nikon publishes a per-type feature table in its Compatible F Mount Lenses document for the FTZ II and FTZ adapters. It is the most detailed per-type breakdown among the sources read for this page, and it is reproduced below with Nikon's own column structure intact — including the plain manual-focus column, which is the reassuring one. Every lens type Nikon lists can at least be focused by hand. Losing autofocus does not mean losing everything.

Two things the table does not show. Nikon notes that even for the fully supported AF-S, AF-P and AF-I types, the electronic rangefinder may not function as expected with some lenses and autofocus fine-tuning may be necessary. And the adapter cannot be used with Nikon's TC-1.4x or TC-2.0x Z-series teleconverters at all, though Nikon does publish a list of AF-S and AF-I teleconverters that work with named lenses through it.

The diagnostic: read two markings on your barrel

You do not need this page to name your specific lens. You need to read the barrel — but two markings, not one. Nikon's table makes the type letter part of the condition, not decoration: the fully supported row reads "AF-S Type G, E, and D; AF-P Type G and E; AF-I Type D". So a lens marked AF-S, AF-P or AF-I and carrying a G, E or D type letter has its focus motor inside and autofocuses through the adapter. Nikon states the rule behind that directly: F-mount lenses with a built-in autofocus motor retain full autofocus abilities. A lens marked only AF expects the camera body to turn a mechanical screw, and neither FTZ nor FTZ II contains a motor to turn it, so it mounts, meters and focuses by hand.

Nikon's Telling Lenses Apart section annotates both markings and shows where on the barrel they sit, with three worked examples: an AF-S NIKKOR 50mm f/1.4G for the fully supported group, an AI AF Nikkor 50mm f/1.4D for AF Type G and D, and an AI AF Nikkor 50mm f/1.4S — annotated "No G, E, or D label" — for Other AF Lenses. Read both markings, not just the first. For the oldest group there is a third tell: Nikon says AI-, AI-modified and Series E lenses have an exposure meter coupling guide on the aperture ring, have no CPU contacts, and carry labels that do not begin with "AF".

Canon has no equivalent split, and importing the Nikon diagnostic here would mislead you. Canon describes the EF mount as a fully electronic mount system that controls autofocus drive by a driving motor in the lens and eliminates mechanical drive or data transmission between body and lens — that was the design from the EOS 650 in 1987. USM and STM are names for motor types: Canon presents the ultrasonic motor and the stepping motor as different actuators chosen for different lens designs, not as the difference between having a motor and not having one. It follows — and this is an inference from those two Canon statements, not something Canon spells out — that an EF lens's barrel marking tells you which motor it uses, not whether it has one, so it does not predict autofocus through an adapter the way Nikon's marking does. Canon publishes no per-type compatibility table. For Canon the honest instruction is to read the lens compatibility section of your specific body's manual.

Things that still go wrong when everything "works"

• Stabilisation is partial. Nikon says in-lens VR combines with on-camera vibration reduction across the pitch, yaw and roll axes, and that for a non-VR F-mount lens all three axes are corrected in-camera. But the same document states the mount adapter does not support synchro VR, the feature that blends lens and on-camera stabilisation.
• Non-CPU lenses need manual data entry. Nikon instructs users of non-CPU lenses to enter focal length and maximum aperture through the Non-CPU lens data option in the camera's setup menu, and ties on-camera vibration reduction for those lenses directly to supplying the focal length that way. Entering the maximum aperture is what gives the camera the other half of the exposure picture. Nikon does not say metering stops working without the entry — its own table shows these lens types supporting all metering modes — but the camera is then working from data you have not given it.
• A crop lens costs you the frame, permanently. With EF-S glass on a full-frame EOS R5, Canon says the approximately 1.6x crop is automatic with no other option, and that areas outside the crop are not recorded in RAW. There is no file to recover later. Nikon's DX equivalent is softer in wording and the same in effect: attaching a DX lens automatically selects the DX image area, and it also disables the Image Dust Off ref photo option. What a crop does to your effective framing is covered on the sensor format guide.
• Set the aperture ring before you mount. Nikon instructs that if an F-mount lens has an aperture ring, you select minimum aperture — the highest f-number — before attaching the lens to the adapter.
• Some lenses are excluded outright. Nikon's incompatible list for the FTZ II/FTZ includes non-AI lenses, IX-NIKKOR, the TC-16A AF Teleconverter, lenses that require the AU-1 focusing unit, several fisheyes and a long run of specific vintage optics by serial number. Nikon adds that individual variation may render lenses outside that list incompatible too, and says not to use force if you encounter resistance.

What this page does not cover

Check yours

For Nikon F on Z, three fields in this order. First, the two barrel markings — AF-S, AF-P or AF-I, and a G, E or D type letter. Both must be present for autofocus through the adapter. Second, whether the lens is a crop-format design: DX rather than FX. Third, your body's own manual under lens compatibility, because the exclusions are per-model.

For Canon EF or EF-S on RF, skip straight to the third field. The barrel marking will not tell you what it tells a Nikon owner, and Canon publishes no per-type table. Your body's manual is the document, and it is where both the EF-M exclusion and the EF-S crop behavior are stated for the model you actually own.

Nikon publishes the full per-type table, the Telling Lenses Apart diagrams and the incompatible-equipment list in Compatible F Mount Lenses, downloadable alongside the FTZ II product page. Canon publishes its statements inside each camera's online manual at cam.start.canon; for the EOS R5 the lens and adapter language sits in the troubleshooting and shooting sections linked below. That same R5 troubleshooting page also carries a warning that slow card write speed can stop movie recording, which is a different problem with a different fix — covered on the memory card guide. All of these documents are free, searchable, and more current than any summary, including this one.

Check it on your own equipment

These take you to the manufacturers and standards bodies the page draws on, so you can look up your exact model.

• Manufacturer specification
  Nikon: Compatible F Mount Lenses (FTZ II / FTZ) — full PDF (opens in a new tab)Nikon's complete Supported Features grid by lens type with both footnotes, the Telling Lenses Apart diagrams showing which two barrel markings to read and where they sit, the CPU versus non-CPU contact diagram, per-type restrictions, the AF-S/AF-I teleconverter list, and the Incompatible Lenses and Accessories list with the do-not-force warning. — download.nikonimglib.com
• Manufacturer specification
  Nikon: Mount Adapter FTZ II product page (opens in a new tab)Nikon's headline compatibility counts — AE with approximately 360 NIKKOR F lenses from AI type onwards, AF/AE with 94 AF-P/AF-S/AF-I lenses — plus the adapter's specifications and its own incompatible-lens listing. — imaging.nikon.com
• Official support page
  Canon EOS R5 manual: lens and adapter limitations (opens in a new tab)Canon's own statements that EF and EF-S lenses require a mount adapter and that this camera cannot be used with EF-M lenses, alongside related troubleshooting notes including the warning that slow card write speed can stop movie recording. — cam.start.canon
• Official support page
  Canon EOS R5 manual: cropping with RF-S and EF-S lenses (opens in a new tab)Canon's wording on the automatic approximately 1.6 crop applied with RF-S and EF-S lenses, the choices offered with RF and EF lenses by contrast, the fact that no other option is selectable with EF-S, and the statement that areas outside the crop are not recorded even in RAW. — cam.start.canon