topic Re: EF 100-400mm f/4.5-5.6L IS II USM compatibility with EOS R7 in EF & RF Lenses

EF 100-400mm f/4.5-5.6L IS II USM compatibility with EOS R7

libbysmith — Wed, 04 Feb 2026 14:20:32 GMT

Hi,

does the canon lense 100-40mm f4.-5.6L Is II USM fits on a canon R7?

Thank you

Re: EF 100-400mm f/4.5-5.6L IS II USM compatibility with EOS R7

March411 — Wed, 04 Feb 2026 14:55:55 GMT

Hey libbysmith,

That lens will function on your R7 but you will need to purchase a Mount Adapter EF-EOS R. It is best to use the original Canon adapter as third party adapters have reported issues such as lens racking and battery drain while the camera is off. New they are around $150 but you can find them used at several Canon authorized sellers.

EF Lenses supporting maximum continuous shooting speed
EF24mm f/2.8 IS USM	EF400mm f/2.8L IS II USM	EF24-105mm f/3.5-5.6 IS STM	EF200-400mm f/4L IS USM Extender 1.4x
EF28mm f/2.8 IS USM	EF400mm f/2.8L IS III USM	EF24-105mm f/4L IS II USM	EF-S24mm f/2.8 STM
EF35mm f/1.4L II USM	EF400mm f/4 DO IS II USM	EF24-70mm f/2.8L II USM	EF-S35mm f/2.8 Macro IS STM
EF35mm f/2 IS USM	EF500mm f/4L IS II USM	EF24-70mm f/4L IS USM	EF-S10-18mm f/4.5-5.6 IS STM
EF40mm f/2.8 STM	EF600mm f/4L IS II USM	EF70-200mm f/2.8L IS II USM	EF-S18-55mm f/3.5-5.6 IS STM
EF50mm f/1.8 STM	EF600mm f/4L IS III USM	EF70-200mm f/2.8L IS III USM	EF-S18-55mm f/4-5.6 IS STM
EF85mm f/1.4L IS USM	EF8-15mm f/4L Fisheye USM	EF70-200mm f/4L IS II USM	EF-S18-135mm f/3.5-5.6 IS USM
EF100mm f/2.8L Macro IS USM	EF11-24mm f/4L USM	EF70-300mm f/4-5.6 IS II USM	EF-S18-135mm f/3.5-5.6 IS STM
EF300mm f/2.8L IS II USM	EF16-35mm f/2.8L III USM	EF70-300mm f/4-5.6L IS USM	EF-S55-250mm f/4-5.6 IS STM
	EF16-35mm f/4L IS USM	EF100-400mm f/4.5-5.6L IS II USM
https://cam.start.canon/en/H001/supplement_0080.html

Here is a link to the Canon website for the Mount Adapter EF-EOS R - $150

Re: EF 100-400mm f/4.5-5.6L IS II USM compatibility with EOS R7

deebatman316 — Wed, 04 Feb 2026 15:01:48 GMT

Hi @libbysmith welcome to the forums. The lens is designed for DSLR cameras. It cannot be directly mounted to your camera. It’s a Mirrorless camera and to use older EF lenses. You must use a mount adapter. As my colleague @March411 pointed out to stick with the Canon brand adapter. 3rd Party adapters cause all sorts of problems. Also not every feature in EOS R series cameras will be supported with adapted EF lenses. Canon however does make an RF equivalent of that lens which is the RF 100-400mm f/5.6-8 IS USM lens. Which doesn’t require the adapter to work.