Olympus IS-1 - Manual (Page 54)

Effects of zoom and its advantages
A zoom is a lens with a focal length that changes
when part of lens moves. In the case of the IS-1,
any focal length between 35 mm and 135 mm can
be selected.
35 mm Wide
Because the peripheral angle of view is wide and
the depth of field is greater, sharp photographs
with clear perspective and contrast can be
obtained.
70 mm
With 70 mm zooming, subjects appear close
up—two times closer than when the lens is posi-
tioned at 35 mm.
100 mm or more
When the lens is set to the maximum focal length
of 135 mm, magnification is approximately four
times greater than at 35 mm, enabling you to
obtain genuine telephoto photographs. As you
increase the telephoto effect, perspective becomes
narrow, and depth of field becomes more shallow.
That means that objects in front of and behind
your subject are more likely to be out of focus.
This can have an interesting effect on snapshots
and portraits.
Maximum telephoto lengths are particularly
useful for taking pictures at sporting events and
for nature photography when you want to get
closer to your subject.
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(WIDE CONVERTER)