How do I turn on real exposure preview on mirrorless camera?

The most recommended workflow for flash photography starts with exposing for the ambient environment, then the adjust your flash to build the light you want to achieve.

But, with newer mirrorless cameras, this can be challenging as they usually will kick the live view into auto exposure when a flash or remote is attached. This makes sense as composure and focus is the primary objective for the live view, a dark preview would be hard to use when setting up your shot.

To take test shots without the flash enabled is an option, but all camera brands have ways to do this easier directly in the view finder.

TABLE OF CONTENTS

• Canon
• Fujifilm
• Nikon
• Sony

Canon

The metering window setting controls how long the live view will be in "composition mode", to enable exposure simulation (and override the metering window timeout) press AF select then SET.

• Press AF Select button 
• Press Set button 

Fujifilm

Fujifilm cameras has exposure simulation ON by default. If this is preferred or not, a good recommendation is to assign a button to toggle this function.

• Press Menu button
• Navigate to Setup
• Select Button/dial settings
• Select Function (fn) setting
• Select button to assign
• Assign to Preview exp./WB in manual mode

Nikon

A button needs to be assigned to "Preview". As the menus may vary between camera models, reference your cameras user guide to find exact instructions.

• Press Menu button
• Navigate to Custom Settings Menu
• Select Controls
• Select Custom control assignment
• Select button to assign
• Assign to Preview

Sony

A button needs to be assigned to "Shot result preview". As the menus may vary between camera models, reference your cameras user guide to find exact instructions.

• Press Menu button
• Navigate to Custom Settings
• Select Custom Key 
• Select button to assign
• Assign to Shot result preview

Note that some keys cannot be assigned to all functions.