Like title mentioned, how does mirrorless or dslr's live viewfinder previews the different shutter speed? In actuality, when the picture is taken, the shutter actually has to close for that amount of time right? So how does the preview work?

  • \$\begingroup\$ "the shutter actually has to close for that amount of time right?" – No. The shutter has to open to allow light through. \$\endgroup\$
    – xiota
    Sep 6, 2019 at 7:13
  • \$\begingroup\$ @xiota To be fair, in live view or a mirrorless camera, the shutter does need to close in order to then open. \$\endgroup\$
    – Eric S
    Sep 7, 2019 at 12:41

1 Answer 1


It doesn't preview the shutter speed, but emulates the total amount of light received for the given aperture, speed and ISO. Shoot anything that moves (a fan for instance) and you'll see that it is not frozen in the preview as it should be if the display were also emulating the actual shutter speed.

  • \$\begingroup\$ But, but, but... I thought with EVFs WYSIWYG? \$\endgroup\$
    – Michael C
    Sep 6, 2019 at 12:01
  • 2
    \$\begingroup\$ @MichaelC yes, with suitable definitions of "see" and "get". \$\endgroup\$
    – xenoid
    Sep 6, 2019 at 12:05
  • \$\begingroup\$ Thanks for your explanation. How accurate is the emulation? How does it work so well? \$\endgroup\$
    – BlackSoil
    Sep 7, 2019 at 4:07

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.