topic Re: Canon 100mm 2.8L macro lens problem\bug with ef to rf adapter on R5 MKII in EF & RF Lenses

Fix for Canon 100mm 2.8L macro lens problem\bug with ef to rf adapter on R5 MKII

frenchrl14 — Tue, 09 Jun 2026 13:18:07 GMT

I had an issue recently with my R5 MKII and the EF canon 100MM 2.8L macro lens. It basically stopped focusing in AF mode. It would work a little, and\or would work far away but not up close then usually after a few minutes it would stop focusing all together. I put the lens on an older canon 40D and no issue. Back to the R5 and same issue. I used another EF to RF adapter, no help. I turned off IS, tried the macro limiter settings on lens no luck, I then determined it was a camera setting, and found it to be the "Lens Drive when AF impossible" setting in AF menu. Set this to ON and problem went away.

Thought i would share because I found nothing online about this and I got really lucky figuring it out. I thought the lens was just going to be useless on my R5II. Hope this helps someone.

Re: Canon 100mm 2.8L macro lens problem\bug with ef to rf adapter on R5 MKII

Jkarl — Mon, 08 Jun 2026 10:54:16 GMT

Just curious what brand of EF to RF adapter are you using?

Re: Canon 100mm 2.8L macro lens problem\bug with ef to rf adapter on R5 MKII

SignifDigits — Mon, 08 Jun 2026 11:45:17 GMT

Thank you for posting this. There are a lot of people that have visited this group only to have them pointed towards that setting, and it has solved quite a few AF problems. Kudos to you for figuring this out on your own. If you will post and mark your reply as a solution (or one of ours) it will help others as solutions get higher priority on search engine results. Thus, anyone with your exact problem will likely see it in a Google search.

Re: Canon 100mm 2.8L macro lens problem\bug with ef to rf adapter on R5 MKII

shadowsports — Mon, 08 Jun 2026 14:27:53 GMT

Greetings,

To ensure accurate information. Lens drive when AF impossible is enabled by default on Canon cameras out of the box. There are certain situations where you may want to turn it off, but it's not a problem or bug, with your camera, lens or adapter choice. It's something that you turned off and then attempted to use AF in a shooting situation with low contrast or while tracking a moving subject where the camera wasn't able to differentiate between the subject or background. In macro photography. this could also happen if you were trying to focus on something closer than the lenses MFD, in this case 11.88in.

Re: Canon 100mm 2.8L macro lens problem\bug with ef to rf adapter on R5 MKII

frenchrl14 — Mon, 08 Jun 2026 17:37:29 GMT

Unfortunately, It froze up at all distances and with plenty of contrast. As mentioned it tended to work at first, if you were 12 or so inches out, but failed if closer. Once it failed it tends to no longer work at any distance and with and object. I am very familiar with how AF works, needing contrast etc.. it absolutely would not work. It worked fine on my 40D, no issues at all. I usually leave that setting on too. I obviously turned it off accidentally at some point. I am just happy I figured it out.