Settings | USER GUIDE |
| 93 |
True Exposure explained |
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Light level at image plane
T fully open
Maximum aperture
Stopped down one stop with True Exposure ON
Stopped down one stop with True Exposure OFF
Time |
T stopped down = T Fully open |
(using True Exposure) |
T stopped down > T Fully open |
(without True Exposure) |
True Exposure is an XCD and HC/HCD lens function that allows the shutter speed to remain unaffected when stopping down. This effect is perhaps not so commonly understood as it is restricted specifically to integral lens shutters as opposed to focal plane shutters.
When a lens is stopped down, the effective shutter speed becomes longer, consequently affecting the set exposure. At slow shutter speeds the effect is minimal but at faster speeds, 1/500s, the effect becomes clearly visible. Automatic compensatory measures in speed setting adjustments are employed.
As compensation can only be put into effect where speeds can be adjusted, this prevents the possibility of adjusting the fastest speed of 1/800s. To counter this, compensatory adjustments
are therefore made to the aperture instead to retain the set exposure. This compensation is not always required and when using flash/strobe as the main light source it is actually undesirable because compensation will result in underexposure. Therefore, when using flash/strobe as the main light source, you should set True Exposure to OFF in Main Menu > Camera Settings > Exposure > True Exposure in the Camera Display.
You can download a complete explanation of this situation from www.hasselblad.com.
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