Hasselblad H4D200MS user manual Stopped down one stop with True Exposure mode OFF

TRUE EXPOSURE

Light level at image plane

Tfully open

Maximum aperture

Stopped down one stop with True Exposure mode ON

Stopped down one stop with True Exposure mode OFF

Tstopped down = T fully open

(using True Exposure)

Tstopped down > T fully open

(without True Exposure)

Time

True Exposure is an HC/HCD lens function that allows the shutter speed to remain un-affected 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, e.g. 1/500s, the effect becomes clearly visible. As Hasselblad knows exactly how the shutters behave in HC lenses, auto- matic compensatory measures in speed setting adjustments are therefore 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 adjust- ments are therefore made to the aperture instead to retain the set exposure.

However, 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 underex- posure. Therefore, when using flash/strobe as the main light source, you should set True Exposure to OFF in Custom Options #13 on grip.

N o t e

You can download a fuller ex- planation of this situation from www.hasselblad.com.

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