Pentax Silkypix K-500 Operating Manual page 253

Using b/L/a Mode
1
Set the mode dial to b, L or a.
2
Set the flash mode to E or F.
3
Set the shutter speed (for b mode) or shutter speed
and aperture value (for L or a mode).
Set so a proper exposure is obtained at a shutter speed of 1/180 seconds
or slower.
4
Press the E button.
The built-in flash pops up.
5
Take a picture.
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