I've recently been spending some time trying to shoot fast-moving things with a variable-aperture zoom. This is annoying; not because I have any real problem with the variable-aperture nature of the lens, but because of a usability issue: In Av or M mode I dial it to f4 (the maximum). Then I zoom in and it gets changed automatically to (say) f5.6. Then I zoom back out and it remains at f5.6 until I adjust it again.

Is there any way, on a Canon R-series camera, to tell it "I always want the widest aperture that is available at the current focal length"? This seems like an obvious and useful function, but I'm not aware of any mode that does it (except perhaps for "portrait" auto settings on older / cheaper models)

  • \$\begingroup\$ I’ll add that to my list of reasons why I need to wait awhile before dumping my DSLR for these newfangled “Mirrorless” cameras. \$\endgroup\$ Commented May 17, 2023 at 16:33
  • \$\begingroup\$ @MikeSowsun I'm not sure there was any way to do this on Canon DSLRs either...? \$\endgroup\$
    – Flyto
    Commented May 17, 2023 at 16:34
  • 3
    \$\begingroup\$ If I set f/4 at 24mm it will change to as I zoom to 105mm, but it ALWAYS goes back to f/4 when I zoom back to 24mm. \$\endgroup\$ Commented May 17, 2023 at 16:36
  • \$\begingroup\$ @MikeSowsun sow Ah. interesting - and that's on a Canon DSLR? Behaviour must have changed. \$\endgroup\$
    – Flyto
    Commented May 17, 2023 at 16:41
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    \$\begingroup\$ Here someone had the same issue on an R7, but the other posts seem to indicate that this should just work... \$\endgroup\$ Commented May 17, 2023 at 17:26

1 Answer 1


Figured out what is happening: The behaviour that I want is actually what happens in Av and M modes. If the f-stop is forced to increased by zooming in, it will automatically reduce again when zooming out.

The reason I was not seeing this is that I was reflexively using the aperture dial before some shots to check that it was set to wide open. Doing this while zoomed in is registered by the camera as a deliberate instruction to adopt the maximum aperture that is available while zoomed in - and hence when zooming out it remains.

So the answer to my question is just "restrain your finger: don't try to open the aperture when it's already open, and it will just work"!


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