topic Re: Depth of Field review button in EOS DSLR & Mirrorless Cameras

EOS 90D How to use Depth of Field preview button

Ramsden — Tue, 03 Feb 2026 14:37:15 GMT

Hi Folks

EOS 90D from across the pond here.

Just looking for a bit of advice/help on the Depth of Field preview button.

To be perfectly honest I haven't used it in anger and wondered if I'm missing a trick as aim to improve my skills.

Also, in my guide book it says that I can alter the setting via Exposure Simulation option in Shooting Menu 2 by selecting Disable.

See attached photo - its not obvious.

Thanks for any tips and advice.

Ramsden

Re: Depth of Field review button

Ramsden — Sun, 01 Feb 2026 13:02:48 GMT

Re: Depth of Field review button

stevet1 — Sun, 01 Feb 2026 16:18:35 GMT

Ramsden,

One way that you can use your DOF Preview button is in conjunction with your exposure lock button.

On my camera at least, the exposure lock button locks your exposure, but only holds that lock for approximately 6 seconds. If you press the exposure lock button (most commonly the * button), and then press and hold the DOF Preview button, it will hold that lock for as long as you want.

On my camera (a T8i), pressing the AF ON button will also hold that exposure lock, and that is the one I use, but the DOF Preview button will do the same thing.

Steve Thomas

Re: Depth of Field review button

ebiggs1 — Sun, 01 Feb 2026 16:29:15 GMT

The DOF button stops down the lens aperture to whatever is the selected lens setting. It supposedly allows you to see the range of focus in the viewfinder. However, it may darken the VF on some models to almost worthless and may not be a very good option.

Re: Depth of Field review button

Ramsden — Sun, 01 Feb 2026 16:43:43 GMT

Hi EB

Yes, mine just darkens the VF. Not much use as it is.