Praktina FX - img009

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,

possible,

you

obtain

the

greatest

depth

of

field

that

your

lens

will '

yield.

The

largest

aperture

is

expressed

!by

the

sm<l.\lest

number

(e.

g.

for

the

Tessar

f/2.8

=

2.8),

and

the

smallest

aperture

by

the

la

'rge6t

number

(e. g.

f/16

=

16).

These

diaphragm

stops

are

set

by

means

of

t(he

red

triangle

on

the

iblatk

lens

mount.

This is how the diaphragm pre-se,

tting

ring

operates

Now

you

may

lift

your

camera

to

eye

,

level

a,

gain

and

snapshot

-

or,

teclmically

speaking,

release

the

shutter.

You

will ,

discover

that

stopping

down

the

diaphragm

does

not

merely

mean

greater

depth

of

focus,

but

also loss

of

light

and,

consequently,

a

'darkened

screen

image.

But

for

focusing,

you

need

a

ground.glass

'ffi'I\'

ge

as

bright

as

you

can

possibly

get.

The

diaphragm

preselecting

ring

is

positioned

immediately

next

to

the

diap

'

hragm

setting

ring

and

is

loosened

by

slight

ptessure

in

the

direction

of

the

camera

body,

whereby

it

,

becomes

rotatable.

Turn

the

ring

until

the

little

re

,d

dot

stands

opposite

the

selected

dia·

phragm

num

'

ber

and

let

the

ring

snap

in

gently.

Make

sure

that

the

'

preselection

ring

clitks

in

quite

close

to

the

setting

ring

and

that

it

is

locked

tightly.

You

may

now

view

and

examine

the

image

with

the

aperture

wide

open,

'

and

just

before

releasing

the

shutter.

you

turn

the

'

stop

ring

clockw>se

a.s

far

as

it

will go.

You

now

have

the

diaphragm

at

the

desired

setting

without

having

to

remove

the

camera

from

eye.level.

5