If you have just moved a DSLR lens onto a mirrorless body-or you want to reuse an older lens-the adapter you choose depends on the mount on the lens and the mount on the camera. The four camera accessories adapters covered here split into two clear groups: two adapters that take Canon EF/EF-S lenses to Canon EOS R/RF bodies, and two that take legacy B4 or M42 lenses to Sony E/NEX bodies. Listed prices run from $28.49 to $129.95, so the fit matters more than the sticker alone.
Quick take
For Canon EF/EF-S lens owners moving to EOS R, the EF-EOS R Lens Mount Adapter at $28.49 is the lowest-priced option of the four, and its description says it maintains autofocus, image stabilization, EXIF, and electronic aperture support. The Canon Mount Adapter EF-EOS R at $129.95 is the Canon-branded version of the same EF/EF-S-to-EOS R fit. For Sony E-mount shooters, the Lens Mount Adapter Ring B4-NEX at $58.99 is built for B4 2/3-inch lenses with manual diaphragm control, while the K&F CONCEPT M42-NEX IV at $30.99 brings M42 screw-mount lenses to Sony E and is listed with a 1-year manufacturer warranty.
Listed price comparison
| Product | Listed price | Price bar |
|---|---|---|
| EF-EOS R Lens Mount Adapter (Canon EF/EF-S to EOS R) | USD 28.49 | |
| Canon Mount Adapter EF-EOS R (Canon EF/EF-S to EOS R) | USD 129.95 | |
| Lens Mount Adapter Ring B4-NEX (B4 to Sony E/NEX) | USD 58.99 | |
| K&F CONCEPT M42-NEX IV (M42 to Sony E) | USD 30.99 |
Decision matrix
- If you want Canon EF/EF-S glass on an EOS R/RF body and a lower listed price, the EF-EOS R Lens Mount Adapter covers the mount at $28.49.
- If you want Canon's own adapter for the same EF-to-RF fit, the Canon Mount Adapter EF-EOS R is the one listed at $129.95.
- If you own B4 2/3-inch lenses and shoot on Sony E/NEX, the B4-NEX adapter ring at $58.99 is the specific bridge.
- If you have M42 screw-mount lenses and want a 1-year warranty on the adapter, the K&F CONCEPT M42-NEX IV at $30.99 is the practical match.
Product notes
EF-EOS R Len Mount Adapter Accessory For Canon EF EF-S Lens To EOS R RF Mount
At $28.49, this is the least expensive adapter in the roundup. Its listing describes a full-function adapter for Canon EF/EF-S lenses on EOS R/RF bodies, including autofocus, image stabilization, EXIF transmission, and electronic aperture control, plus gold-plated contacts and an aluminum-alloy body. The snap-on fit is listed in the attributes. Choose it if you want to put EF/EF-S lenses on an EOS R body without reaching the higher price of Canon's own adapter. The trade-off is that no brand name is attached, so it is not the Canon-branded part, and the feature list comes from the listing rather than from Canon's official documentation.
Canon Mount Adapter EF-EOS R for Canon EF/EF-S Lens to EOS R Camera
This is the Canon-branded entry in the group at $129.95. The title points to the same mount conversion-Canon EF/EF-S lenses to EOS R cameras-and the attributes add Canon EF lens fitting and type: lens adapter. If you prefer an adapter carrying Canon's own name for the EF-to-RF conversion, this is the product that matches that need. The limitation is practical: it carries the highest listed price in this comparison, and the other EF-EOS R adapter at $28.49 lists more electronic-support features. For someone who doesn't need a Canon-branded adapter, the lower-priced product covers the same printed mount compatibility.
Lens Mount Adapter Ring B4-NEX for B4 Lens to Sony NEX E-mount Camera
At $58.99, this adapter sits between the two Sony-compatible options. Its listing says it lets you use a 2/3-inch B4 mount lens on Sony NEX E-mount cameras such as the α6300, α6400, α6500, and α6600, with a construction of brass and aluminum. The diaphragm control is manual, and the package includes the mount adapter ring. Choose it if you have a B4 lens and want the specific B4-to-E bridge. The limitation is that it does not provide automatic diaphragm control-the listing says the aperture is set manually-so you'll handle diaphragm control yourself rather than relying on the camera to stop the lens down.
K&F CONCEPT M42-NEX IV Lens Mount Adapter For M42 Lens to Sony E Mount Camera
The K&F CONCEPT adapter at $30.99 is the closest competitor to the B4-NEX in price and purpose. It mounts M42 screw-mount lenses to Sony E-mount cameras and is listed with a 1-year manufacturer warranty. The listing highlights precision high-tolerance craftsmanship and includes a practical note about checking focus through the viewfinder even at infinity, plus a reminder that a "No Lens Attached" warning can appear. Choose it if you have M42 lenses and want a lower-priced adapter with a warranty. The limitation is that it's specifically for M42 screw-mount lenses, so it won't help Canon EF lenses or B4 lenses; and it requires you to work with the manual-focus caveats listed.
Which adapter should you pick?
If you're adapting Canon EF/EF-S lenses to an EOS R body, decide between the $28.49 EF-EOS R adapter and the $129.95 Canon Mount Adapter EF-EOS R. The lower-priced one lists the electronic support you'd want; the higher-priced one brings Canon's brand and identifiers. For Sony E/NEX shooters with legacy lenses, choose the $30.99 K&F CONCEPT M42-NEX IV for M42 screw-mount glass and a warranty, or the $58.99 B4-NEX ring if you have a B4 2/3-inch lens and are okay with manual diaphragm control.
