Canon R5 focusing problems with Sigma Art EF-lenses.

[pipercarter]

I’m Having problems focusing with Sigma 24-70mm & 18-35mm on Canon R5 with either adapter. Can anyone help? I’ve purchased both adapters because I thought maybe the original one didn’t work but the control ring doesn’t work either. Or it could be my settings. I’m nit sure why my EF lenses won’t focus.

[Tronhard]

---

@Waddizzle wrote:

---

@Tronhard wrote:

Do the images show significant vignetting? If so, it would make me suspect that the sensor is not auto cropping the image from 45MP to 17MP and is capturing an angle of view the lens was never meant to deliver.

If you check your manual on P143 and 900 it addresses these issues. You can confirm that the camera is working in crop mode, and, if not, set it as such - then re-test.

---

I am not aware of any third party manufacturers that use the actual EF-S mount, when having the EF mount works just as well on all Canon bodies.  So, I would not expect the camera to automatically switch to a 1.6 crop.

---

It's a new complication with the Canon FF R system. It was not so much an issue on FF DSLRs.  Certainly, having a 3rd party APS-C lens, adds a significant variable to the system.  I have tried a couple of Canon native APS-C lenses with a Canon adapter as an experiement, and they have worked ok, although the loss of pixel capacity by a factor of 2.56 is a bit rough.