I was messing around in my cameras settings and I think I may have changed something that affected the viewfinder. Now, in manual mode, when using the viewfinder it does not show the changing exposure. The meter appears at the bottom of the display, but the image itself doesn't change.

I have already tried a factory reset, but that didn't seem to fix it, so maybe it wasn't a setting. I just don't know.

  • 1
    \$\begingroup\$ Possible duplicate of What is it called when aperture and exposure are previewed on the LCD screen before the shot is taken? \$\endgroup\$
    – mattdm
    Jul 30, 2017 at 0:56
  • \$\begingroup\$ Your question is confusing. You seem to be saying that the brightness of what you see in the viewfinder is changing. The brightness in the viewfinder should never change. But then in the comment that you erroneously posted in the answer section it seems that you are saying that the information that should be displayed within the viewfinder has disappeared. It would be helpful if you would clarify what you were talking about. \$\endgroup\$
    – Alaska Man
    Sep 23, 2019 at 4:18

1 Answer 1


When you say viewfinder, do you mean the small glass thingie that you peer through with one eye, or the large LCD screen on the back of the camera? The glass thingie (what most people call the viewfinder) does not, and cannot, show the effect of changing exposure settings. Granted, there is a depth-of-field preview button below the lens mount release button, but pressing that only darkens the viewfinder to the degree that the aperture is stopped down; it is not meant to provide an exposure preview, and it cannot show the effect of changing shutter speed or ISO.

If you mean the LCD, perhaps you accidentally enabled Auto ISO? That would have the effect of telling the camera to automatically adjust the ISO to compensate for manual settings that would result in under- or overexposure. Since the camera will adjust ISO to achieve what it thinks is proper exposure regardless of your manual exposure settings, the preview on the LCD would not change if Auto ISO is enabled (unless you set the aperture and shutter speed to such extreme values that the camera is unable to compensate with ISO).

  • \$\begingroup\$ Incorrect chulster. I have been using the viewfinder (internal readout, not LCD) since I have had my T2i. For some reason, Friday night, it simply stopped working and I am baffled. I have had this camera for nearly a decade without issue. Now I can’t see my center weighted, F.*, ISO - all of which I could see perfectly, and make adjustments to, all on the fly and without taking the camera away from my face. I don’t have any clue as to what went wrong. \$\endgroup\$
    – CE Robin
    Sep 22, 2019 at 18:02

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