naked eγe. And it can still easilγbe
seen
，
when stopping down to small
apertures for depth-of-field contro
l.
When using longer telephoto lenses or
close-up attachments
，
the upper edge
of the image maγbecome slightly shad-
ed
，
because the reflex-mirror does not
reflect the entire cone of light raγs.
However
，
this has no effect whatsoever
on the actual picture.
The eγepiece of the ALPA 10d is equip-
ped with a large
，
soft-rubber eγecup to
exclude extraneous straγlight. It can be
rotated for taking horizontal and vertical
pictures. Its bayonet mount offers in-
stant interchanging with a magnifier or
angle viewfinde
r.
The standard 1:1
ocular of the ALPA viewing sγstem can
be replaced bγa special 1:0
，
7 eγeplece
，
so that people who wear glasses or have
recessed eγes easilγsee the entire
image. An adapter with standard diop-
ter or prescription lenses snaps easilγ
into the eγecup.
2) Focusing
Turn the focusing ring on the lens to
set the proper distance. You have your
choice of 3 focusing methods:
a) Groundglass. Turn distance setting ring
until image is critically sharp.
b) 45° Diagonal Split
﹒
Image Rangefinder
The standard groundglass screen has a
built-in optical rangefinder with a 45
。
diagonal split-image
，
formed bγa pair
of prisms which appear as 2 semi-
circles (Fig. 5). You can pinpoint focus
for both horizontal or vertical lines
instantlγ-with anγlens
，
at anγdistance.
Select a specific detail in the subject to
be photographed and turn the focusing
ring until the image in the 2 semi-circles
is in perfect alignmen
t，
with no displa-
cement at the dividing line. Now γour
focus is perfect (Fig. 3 and 4).
The clear glass ring (aerial image)
around the rangefinder (diam. 5 mm)
permits γou to see everything visua
l!
γ
sharp
，
which is in front or behind the
depth-of-field zone of sharpness on the
groundglass. You can also use it for
rapid location of the subject you wish to
Fig. 5
photograph. And last but not least
，
it is
indispensable for extreme close-ups at
high magnifications and photomicro-
graphγ. The image is in perfect focus
when both the aerial image and one of
the two lines (L Fig. 4) appear equally
sharp.
Both semi-circular prisms will appear
uniformly bright under normal condi-
tions. Under certain circumstances
(smaller lens apertures
，
close-up photo-
graphγ) one of the semi-circular prisms
maγappear to be shaded. In this case
γou can alignγour image between the
other
，
bright prism of the split-image
and the clear glass ring.
Important: The perfected optical sys-
tem of the ALPA 10d with 1: 1 LIFE size
magnification on the groundglass
makes focusing remarkably easy. How-
ever
，
this should not temptγou to take
photographs of subjects which cover
only a small part of the entire area. You
can easilγavoid this bγcomparison
with the 3 rapid reference scales on the
ALPA groundglass: The diameter of
the rangefinder is 3 mm
，
the width of the
clear glass ring is 1 mm which brings
the total diameter to 5 mm. The overall
length of the cross-hair is 10 mm
(Fig. 3
，
4 and 5). These 3 reference
scales clearlγindicate when a different
(telephoto) lens ought to be used. Theγ
are even more useful for measurements
and comparisons in macro-photogra-
phy.
c) Distance Scale
ALPA interchangeable lenses are cali-
brated with distance scales to preset a
specific distance
，
where focusing on the
5
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