topic Re: Locking the Exposure (AE Lock) in EOS DSLR & Mirrorless Cameras

EOS 90D: Locking the Exposure (AE Lock)

Ramsden — Thu, 18 Sep 2025 19:15:48 GMT

Hi folks

Minor detail as I work through the manual for my EOS 90D, i can't seem to lock the exposure as described in the screen shot and I cant see the * icon.

I expect that I've got another option open that's blocking it- but after a couple of hours, I give up.

Help please

Ramsden

Re: Locking the Exposure (AE Lock)

stevet1 — Thu, 18 Sep 2025 16:01:57 GMT

Ramsden,

On my camera (a T81), if you press that asterisk button, a little white asterisk appears in the bottom left-hand corner of my screen. By default, it will only hold that lock for about six seconds.

I have back button focus set up, and I've found that by holding down that AF-ON button while in Servo mode, I can hold that lock for as long as I keep pressing down on that AF-ON button. The Depth of Field preview button on the front of the camera will do the same thing.

Steve Thomas

Re: Locking the Exposure (AE Lock)

Waddizzle — Thu, 18 Sep 2025 16:15:56 GMT

What AF mode are you using? One Shot AF locks metering when it locks focus.

Servo AF locks metering and focus when the shutter is fired.

Re: Locking the Exposure (AE Lock)

Ramsden — Thu, 18 Sep 2025 19:13:17 GMT

Thanks Steve, thats really helpful.

I'll try it out later.

Ramsden

Re: Locking the Exposure (AE Lock)

Ramsden — Thu, 18 Sep 2025 19:25:50 GMT

Tried that, but still not locking, and no *

I'll keep trying - its not a big issue but nice to have.

Thanks

Ramsden

Re: EOS 90D: Locking the Exposure (AE Lock)

Waddizzle — Thu, 18 Sep 2025 21:10:41 GMT

“ Tried that, but still not locking, and no *

I'll keep trying - it’s not a big issue but nice to have. “

I am uncertain what you tried. One Shot AF will always lock metering when it locks focus. The camera will [BEEP] when it does. This always happens, no ifs, ands, or buts. The user cannot alter the behavior.

But, all bets are off when using Servo AF. Metering and focus lock when the shutter is fired. If you need to lock metering before the shutter is fired, then you must use [*], auto exposure lock, button. This is the default behavior for the button.

If the user has reprogrammed the button to a custom function, then the default behavior is lost until the user restores the default behavior to the button.

Re: EOS 90D: Locking the Exposure (AE Lock)

zakslm — Fri, 19 Sep 2025 04:17:29 GMT

Ramadan,

Try this if you use back button focus:

1. Press the “Q” button on the back of the camera.

2. Touch the Custom Control function icon on the back screen.

3. Touch the Shutter button AE Lock icon

4. Exit the menu.

This is makes the back button the only way to activate focus (except in A+ Mode and maybe some SCN modes) and locks exposure when you press the shutter button down half way (and hold it). Then you can recompose, press the back button AF ON button to focus then press the shutter button down the rest of the way to take the photo.

Good luck!

Re: EOS 90D: Locking the Exposure (AE Lock)

Ramsden — Fri, 19 Sep 2025 10:44:49 GMT

Hi Waddizzle

Thankyou so much! You 'hit the nail on the head'

I had watching Simon D'entremont Back Button Focus video and got carried away with the other button options.

Made my day.

Re: EOS 90D: Locking the Exposure (AE Lock)

Ramsden — Fri, 19 Sep 2025 10:51:20 GMT

Here's the proof ☆

Re: EOS 90D: Locking the Exposure (AE Lock)

Ramsden — Fri, 19 Sep 2025 14:11:50 GMT

Hi LZ

That's a great combo for the buttons. I'm having fun here trying this out. It seems to require a lot of delicate dexterity.

Thanks for your help guys. I've really learnt so much this last couple of days. I can't believe I've this camera nearly 2 yrs - but they did 'warn' me that there was a lot to get my head around, and into.

Loving it....

Re: EOS 90D: Locking the Exposure (AE Lock)

Ramsden — Fri, 19 Sep 2025 17:36:54 GMT

Hi (again)

I really like this combination and been trying it out indoors with my dog! It's so flexible and providing great shots to my untrained eye.

I sat in my garden for 30mins hoping to catch a bird or two, but its grey and miserable here in the UK.

Thanks