Nikon D90 User Manual page 11

Turn the countersunk bolds in without using any pressure so that the

two shells are nicely put together. This point is reached when the
tightening suddenly generates resistance.
Check all operational switches in the back shell of the camera. It is

possible that some pressure has to be used to operate the buttons. Due
to the water pressure all buttons are squeezed, so this is the normal
situation of operation.
Mount accessories such as flash arm, handle, protection cap, etc...
We strongly recommend doing this first mounting on a table. When one is
forced to work on a floor (ship deck, tent, cabin, ...) a clean towel should be
used as a clean surface to avoid all kinds of dirt. Especially the first time,
you should give yourself all the time needed to practise all these steps. Af-
terwards you will notice that it only takes a couple of minutes to mount your
camera.
Opening the housing:
Before the housing should be opened, see to it that the housing is

properly rinsed with fresh water. Make sure that the housing is dry so
there is no more water left that can work its way inside when it is
opened.
Put the housing down with the port facing down.

Loosen the bolds.

Remove the back shell gently from the front shell. When resistance

occurs while opening see to it that the cause of this resistance is put
right before continuing. If not, damage to the housing or the camera
may occur.
Hugyfot Housing for Nikon D90 11 User manual