Ihagee EXA IIa, Manual

Page: 14 / 44

8
ting scale against the red setting mark. The
distances in meters or feet are measured from
the camera back to the subject. If the camera
is fitted with a Distance Meter or Fresnel Lens
focusing screen, then the image can also be
focused by means of a split-image rangefinder,
which provides a two-fold check on the accuracy
of focusing. For further details see page 17.
The lens aperture is set by means of the dia-
phragm setting ring (4). The smaller figures,
e.g. 2.8,4, indicate the larger lens apertures;
these permit the use of fast shutter speeds, but
provide only slight depth of field. The larger
figures, e. g. 16, 22, indicate small lens aper-
tures, requiring longer exposure times (slower
speeds), but provide great depth of field.
The expression “depth of field” means that
subjects at widely differing distances from the
camera will be recorded sharply on the film.
The extent of this depth of field zone is shown
by the depth of field scale (6) on the lenses;
on either side of the red focusing mark will be
seen a series of aperture values; by reading
off the distance figures opposite the aperture
value corresponding to the diaphragm setting
intended for taking the picture, it is possible
to see where the depth of field zone will begin
and end. If the aperture figure on one side rs
opposite the infinity symbol (∞) or even beyond
it (reading from the center), then the depth of
field extends to infinity. See page 14 regarding
the automatic depth-of-field indicator on the
Jena Pancolar I 2/50mm lens.
Three examples : distance scale set to ∞ (infin-
ity), aperture f 11 depth of field from approx. 5
meters (17 feet) to infinity; see Fig. 6.
Distance scale set to 5 meters (17 feet), ap-
erture f 8 (10 feet) to well beyond 15 meters
(approx. 23 meters or 75 feet); see Fig. 7.
Distance scale set to 2 meters (61/2 feet),
aperture f 5.6 - depth of field from approx. 1.6
meters (2 1/2 feet) to 2.5 meters (8 feet); see
Fig. 8. Use a large diaphragm aperture for fo-
cusing in the reflex viewfinder in order to obtain
a brilliant image and then stop down just before
the exposure. It is not necessary to move the
camera from eye level in order to do this, since