March 21, 2023

Canon R5 - using EFs lenses

This is a mirrorless camera, so it can be used with almost any lens on the planet.

See below for an important issue with EFS lenses that has bitten me twice.

In particular, the Canon R5 can accomodate EFS lenses that formerly only could be used on APS-C cameras. With a full frame DSLR, these in general could not be mounted because the rear lens element was in the path of the big full frame mirror. Now there is no mirror and this is not a problem. Not only can they be mounted, but the camera detects them and switches to using only the central part of the sensor (you get 17 megapixels rather than 45).

I have only 3 EFS lenses:

In truth, there is no reason for me to use any of these other than perhaps the 60mm macro. I have the 17-40 L lens, which any sensible person would choose in lieu of the 10-22. The 18-55 is a 28-88 mm equivalent, and I have the 24-70 f/2.8 L lens.

When I first tried using the camera with my two EFS lenses, it failed to work. I got erratic behavior with clicking noises and the camera reporting that it was switching in and out of manual focus mode. I called Canon the next day, expecting to be told that these old lenses were not supported. The fellow told me to clean the contacts using a dry microfiber cloth. I did and now both work perfectly.

What I have discovered subsequently is this. If you change lenses with power on, you get into this mode. And you don't get out of it until you mount a regular EF lens. Just turning the camera on and off won't fix it! Of course it is totally user error and the wrong thing to change lenses with power on. Why this yields trouble only with the EFS lenses is entirely unknown to me. But the fix is clear -- turn camera power off before changing lenses, EFS or otherwise.

APS-C option

This is sort of related to EFS lenses, so here we go. The R5 camera allows several crop options to be selected if a full frame lens is mounted. You can select the 1.6x APS-C style crop, or 1:1, or 4:3, or 16:9. Not only that, but you can assign a button to activate and deactivate the selected crop mode. You do get less pixels, and you could indeed perform the cropping later in post. One fellow who is a wildlife photographer finds it useful to assign a button to this so he can have a way to quickly "zoom in" and compose animal shots. You also can select (for crops other than 1.6) whether to mask out or outline the cropped area in the viewfinder.
Feedback? Questions? Drop me a line!

Tom's Digital Photography Info / tom@mmto.org