Although
special domes do not
have any effect in air
they offer significant
advantages underwater.
Light rays pass unrefracted,
image quality improves
considerably and the
angle of coverage does
not change. In water
the dome glass is like
a negative power lens.
It creates a virtual
image of the real subject
located very close to
the front glass. The
camera has to be focused
on this virtual image.
To compensate for the
power of the dome and
give you the full focusing
range underwater, a screw-on
+ 2 with DP-FE2 or +4
close-up (dioptre) with
DP-SW lens is required
for all lenses except
full frame fisheye, which
have no front filter
threads! |
