Is it normal for the burst rate to slow down when you stop down the aperture?

Wintereater wrote:

I turned off exp simulation, and it didn't fix it. However, I did discover something weird. So at max aperture (f/5.0 in my case), servo AF works as expected (7fps). Stopping down from 5.6-8.0 it slows way down (3-4fps), but from 9.0 and above, it quickens back up noticably (6 fps), although not to max speed. I'm so confused. I have every setting set to manual so I don't know what could possibly be changing.

Did you actually observe your aperture as I recommended? It’ll be an eye-opener. At many exposure combinations the lens will remain stopped down or partially stopped down (in Servo AF mode). The ISO and E/V of the scene will also affect this. If you watch, you’ll see that the aperture will remain (wide) open at other times.

I’d presume that this behavior is to facilitate AF (and maybe other functions?)

Edit: after turning off my camera and on again, anything below max aperture resulted in the same, below max speed burst rate, but it was consistent at all apertures for some reason. I even turned off auto white balance but no change.

Maybe try resetting your camera back to Factory Default (always a good starting point).

Also, if the exposure sim. and aperture thing were true, then the slowdown when using one-shot af shouldn't be happening.

True.  As to why your framerate is slowed in One Shot AF mode, perhaps the lens is partly to blame. Check lens firmware?

I don’t recall a slowed framerate when I had my M5.  I always had all in-camera processing disabled though.  Check all of your settings.

Since you mention that your Canon lens exhibits largely the same issue, it has to be something common to both (as you’ve been speculating).  Have you tested this in different environments?  You aren’t using flash by chance?  (The M5’s responsiveness is slowed greatly).

Well, good luck to you.  Be sure to report back!

R2