The "Industar-26M", "Jupiter-8" and the fixed version of the "Industar-50" do not
require the above mentioned operations, as their mounts are permanently fixed in the
camera bodies.
The lens is irised by rotating diaphragm setting ring 13. The desired lens opening
figure is set on the scale provided on ring 12. The lens should be irised before
focussing.
For focussing, the lens is rotated in its thread by operating lens focussing lever 14 of
the sliding "Industar-50" lens or the focussing ring of the fixed "Industar-50" lens. In
the initial ("
∞
") positions, the lens mounts are locked by a spring-loaded button
provided on the focussing lever. To release the lever for operation, it is necessary to
press this button.
The lens travel is limited by stops. Distances to the sharp focussing plane are read off
distance scale 10. The distances are indicated by an index with graduations of depth-
of-field scale 11 spaced symmetrically on either side of the index.
Focussing is done with the aid of the optical range-finder. Observing through range-
finder eyepiece 19, lay the lens to the object to be photographed. In this event, the
central part of the range-finder field-of-view shows a yellowish field against a bluish
background.
Within the borders of this square field, the object observed is seen double-imaged if
the object is not infinitely distant (any distance less than 100 m).
Objects having sharp contours should be selected for focussing. Turn the lens by the
focussing lever (or the focussing ring) to align the two images of the object.
This done, set the lens accurately for the distance to the object to be photographed,
and read this distance off distance scale 10. This focus setting is sure to produce a
sharp picture if the camera is held firm at the picture-taking moment, and the
photographed object is still or moves but not very quickly.
Remember that if the object is located at a distance shorter than 1 m, it is impossible
to superimpose the double images upon each other, and it is vain to use the range-
finder.
Sometimes in the photography practice it is either impossible or inconvenient make
use of the range-finder. In such cases, the lens distance setting can be done directly by
the distance scale graduated in meters. The distance to the object to be photographed
should be known before or measured on the spot.
The view-finder combined with the range-finder in the common field of view
provides for simultaneous framing of the photographed scene. For correct framing,
bring your eye as close to range- and view-finder eyepiece 19 as possible. Apply the
eye strictly to the centre of the eyepiece so that the yellowish-tinted square field is in
the centre of the view- and range-finder field-of-view. Non-observance of this
condition brings about poor picture framing.
The camera view-finder is designed for use with normal lenses of 5-cm focal length.
All the other lenses require view-finders with corresponding picture fields, or a
multifoc view-finder intended for use with five different lenses characterized by
different focal lenghts. Attachement view-finders are inserted in shoe 20 provided on
the camera top surface.
It is advisable to make use of depth-of-field scale 11 when taking pictures, consisting
of paired graduations symmetrically spaced on either side of the index mark and
marked to indicate the lens opening figures. Two distances within which all objects
are produced with sufficient sharpness on the picture are always read against these
graduations on distance scale 10; these two limiting distances are called the close and
far limits of the depth of field.
