Pentax K-7 Operating Manual page 111

EV Bar
The EV bar appears on the LCD panel
and viewfinder in M mode. The
appropriate exposure is set when | is in
the middle of the EV bar. If it is towards EV bar
-, it is underexposed. If it is towards +, it
is overexposed. If the value exceeds the range of the EV bar (+5.0),
the "+" or "-" blinks.
Exposure Warning
If the subject is too bright or too dark, "+"
or "-" in the EV bar will blink in the
viewfinder and on the LCD panel.
Combining with AE-L
Press the AE-L button (p. 116) to record the exposure value in
Hyper-manual. If the shutter speed or aperture is then changed, the
combination of shutter speed and aperture changes while the
exposure value is retained.
Example:
If the shutter speed is 1/125 seconds and aperture is F5.6 and is
recorded by pressing the AE-L button, and the shutter speed is
changed to 1/30 seconds with the front e-dial (_,'_:), the aperture
automatically changes to F11.