I have just changed the focusing screen; something I have done now a few times. Now "normal" metering does not occur in auto or manual focus. In live view all ok. Using the eyepiece produces exposure times of minutes rather than fractions of a second! Changing EV doesn't seem to be of use.

To attempt to work around this problem I have a changed lenses, taken the memory card and battery out for 30mins, and reset to factory settings - all to no avail.

I have read somewhere that there is an eye piece light sensor? If there is is it blocked and how do I find it?

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    See if you can find anything useful in another question about can a new focusing screen affect exposure metering? Mar 16 '13 at 7:34
  • Have you tried removing the new focusing screen to check for proper installation? You may have inadvertently put it in backwards. If so, the tab will not seat correctly and the screen will not be properly squared. Is the viewfinder also dimmer than before? You may have also allowed something else that isn't supposed to be in the light path get in front of the metering sensor.
    – Michael C
    Mar 16 '13 at 15:41

Did you change the custom function option to select that you're using a different focussing screen?

In my 50d and 6d there's that custom function to pick a focus screen from the EF-D or EF-A, etc. They say that depending on the focus screen exposure stuff varies. So if you haven't done that then maybe that's why it's bogus.

  • Good idea Peter! and nice edit as well!
    – dpollitt
    Apr 19 '13 at 18:05

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