Canon Speedlite 58OEX Instruction Manual page 23

Displayed Flash Output Figures
When you change the flash output during shooting, the table below makes it
easier to see how the stop changes such as 1/2 -0.3
-+
1/2
-+
1/2 +0.3. You
can see how the stop changes when you increase or decrease the flash
output.
For example, when you decrease the flash output to 1/2, 1/2 -0.3, or 1/2 -0.7,
and then increase the flash output to more than 1/2, 1/2 +0.3, 1/2 +0.7, and
1/1 will be displayed.
Sample Flash Output Figures
Figures for decreased flash output
-+
..........
1/1 -0.3 1/1 -0.7 1/2 -0.3 1/2 -0.7
...........
1/1 1/2 114
1/2 +0.7 1/2 +0.3
1/4 +0.7 1/4 +0.3
+-
Figures for increased flash output
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