04-22-2026
01:38 PM
- last edited on
04-23-2026
07:59 AM
by
James_C
I'm trying to slowly work up a bunch of notes on Canon cameras. I've mentioned this before in this forum. I've never really thought about it before but the shutter button on this camera and I think every Canon camera I've ever owned can be set to "AE lock (while button pressed)". On the R5 Mk II, this setting can only be put on the half press of the shutter button.
I didn't realize this but "metering" is active all the time. I set my camera to manual mode with auto ISO and as I pan around, the ISO is changing without me touching the shutter button. It doesn't matter how the half press of the shutter button is programmed. Without touching the shutter at all, the ISO changes as I pan around.
The "metering start" that the other possible options of the half press of the shutter button can be set to is actually not really true. Metering is started as soon as the camera comes out of sleep.
Just as the text says, when the half press of the shutter button is programed to "AE lock (while button pressed)", the AE is locked when the shutter is half pressed. In my test, the ISO is fixed while I pan around. With the other three possible settings, the ISO continues to change as I pan around while half pressing the shutter button. (Again... no surprised). The surprise to me is that metering is always active unless the camera is sleeping.
Solved! Go to Solution.
04-22-2026 06:44 PM
I might need to clarify a little. I touch the shutter button and this wake up the camera and starts an 8 second timer. During that time, without holding the shutter half way down, the exposure is changed as I pan the camera around. I can see the ISO numeric reading changing. After 8 seconds, the ISO reading switches to AUTO and it doesn't change after that until I touch a button.
My R7 appears to operate the same way.
04-22-2026 02:37 PM - edited 04-22-2026 02:48 PM
“ I didn't realize this but "metering" is active all the time. I set my camera to manual mode with auto ISO and as I pan around, the ISO is changing without me touching the shutter button. “
Is “Preview AF” enabled? Pre capture?
04-22-2026 03:16 PM
Preview AF is off and I am in single shot mode of pre capture can't be on. Is it different for you?
04-22-2026 03:31 PM - edited 04-22-2026 03:56 PM
I am not by my camera.
What is your metering timer set to?
04-22-2026 05:46 PM - edited 04-22-2026 05:55 PM
pedz,
In your post, you don't say if you have kept your focus lock on the half-press if the shutter button, or if you have switched to back button focus.
If you have kept it on the shutter, I can foresee one situation whee you might run into some difficulty. Let's say you want to do a silhouette. If you meter off the sky and lock you exposure, and keep your shutter half pressed, if you are in One-Shot focus mode your focus will still be on the sky and not on the subject in front of you as you recompose your shot.
If you are in Servo focus mode, the exposure will lock, but the camera will continue to re-focus as you swing your camera around.
I have a T8i, and I still left my AE lock on the * button. It will lock the exposure, but only hold that lock for about six seconds. I changed my focus to the AF-ON button, and if I hold that button down with my thumb, it will hold that focusing and metering lock as long as I keep that button pressed down. Pressing down on the Depth of Field Preview button will also hold that metering lock.
Steve Thomas
04-22-2026 06:44 PM
I might need to clarify a little. I touch the shutter button and this wake up the camera and starts an 8 second timer. During that time, without holding the shutter half way down, the exposure is changed as I pan the camera around. I can see the ISO numeric reading changing. After 8 seconds, the ISO reading switches to AUTO and it doesn't change after that until I touch a button.
My R7 appears to operate the same way.
04-22-2026 06:48 PM
I am not thinking about focusing nor really about taking photos. I am just exploring how the camera works. I set the shutter button to each of the four different possible settings and then tried to explore what the camera seemed to be doing with the button not pressed as well as half pressed.
04-22-2026 07:08 PM
“ might need to clarify a little. I touch the shutter button and this wake up the camera and starts an 8 second timer. During that time, without holding the shutter half way down, the exposure is changed as I pan the camera around. I can see the ISO numeric reading changing. After 8 seconds, the ISO reading switches to AUTO and it doesn't change after that until I touch a button. “
That is normal behavior for when AF Start has been removed from the Shutter button.
” Preview AF is off and I am in single shot mode of pre capture can't be on. Is it different for you? “
BTW, single shot mode is a drive mode, not an auro focus mode. I assume you mean One Shot AF. One Shot AF locks exposure when it achieves a focus lock. Servo AF locks exposure when the Shutter is fired:
04-22-2026 07:14 PM
One more thing, you cannot assign the same function to more than one control.
04-22-2026 07:34 PM
@pedz wrote:
I might need to clarify a little. I touch the shutter button and this wake up the camera and starts an 8 second timer. During that time, without holding the shutter half way down, the exposure is changed as I pan the camera around. I can see the ISO numeric reading changing. After 8 seconds, the ISO reading switches to AUTO and it doesn't change after that until I touch a button.
My R7 appears to operate the same way.
That is correct. Once you start the timer the function controlled by the timer takes command until it times out.
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