User manual

ManualsBrandsKodak ManualsDigital CamerasNo 3A Series II

Table Of Contents

No. 3A Kodak Series

II

- 13

negative or print.

It

depends

upon

the

distance be-

tween the s

ubject

and

lens,

the

focal

length

of

the

lens

and

the size of the stop opening used.

The

smaller

the

stop opening

the

greater

the

depth

of

focus. See the table on page 12 for the

depth

of

focus

or

range of sharpness of

the

No. 3A

Kodak

Series

II.

THE

"i."

SYSTEM

A lens is

sa

id

to

work

at

a certain

"speed;"

this

means th

at

the lens will give a s

harp

image from

corner

to

corner of

the

film, with an opening a cer-

tain

prop

ort

ion of

its

focal length.

The

focal

length

is the distance between

the

lens

and

the

film when

the

Kodak

is focused for infinity

It

should be

borne clea

rly

in mind t

ha

t this

"s

peed" depends not

upon

the

size of the opening,

but

upon

the

size of

the opening

in

p

ro

port

ion

to

the fo

ca

l length

of

the

lens.

The

lens

that

will give

sharp

images with

the

largest opening is said to

have

the

greatest

"speed

."

The

proportional size

or

"value"

of

the

stop

open-

ing is designated

by

the

"f"

number

a

nd

is

the

quo-

tient

obtai

ned

by

dividing the focal le

ngth

of the

lens

by

the diameter of the opening.