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(3)
Constant F ·Number
A convent ional fixed focal length lens
requires
troub lesome F/stop calcu lations
depending
on
the
object
distance.
Tamron's
innovative
focusing
system
allows you to maintain a constant
light
transmission
while focusing so
that
the
F-number does
not change at any
focus
settings
from
infinity
to
close
up
(macro
),
Therefore,
you
can
obta
in
optimum exposure
time
without any
correction even
in
auto
flash photo-
graphy. which so far, required obta
ining
a corrected va lue
by
means of
guide
numbers.
In
add ition, w ith the te le-
macro
capab
ility
of the
T
amron
mirror
lens
permitting
the
use
of an auto
flash
at
the
m
ini
mum
distance
of 1.1 meters
(f
or 350mm F5.6) or 1.7 meters,
(for
500mm FB), high-speed macro
photo-
graphy utilizing an auto f lash
is
possibl e.
(4)
Silver-Evaporated Reflex Mirrors
In
order to increase
fight
transmission
eff ic iency, your new
Tamron mirror
lens
incorporates specia
l
silver-evaporated
re-
flex mirrors
rathe
r
than the
conventional
mirrors
whose su rfaces are coated with
alumi num.
With
two reflex
mirrors, the
total reflection percentage within
a lens
havin.Q
aluminum -coated
mirrors
be-
comes 60%
or
less. However,
Tamron
h
as
succeeded
in
obtaining a reflection
per-
ce ntage as
high
as 80% or
more with the
sil
ver-evaporated
reflex
mirrors.
Th
e
specia
l
sil
ve
r
evaporat ion which
is
ap-
plied
to
the
reflex mirrors
is
extremely
durable.
The degree
of
durability
ex·
ceeds
t
he requirements conta ined
in
the
MIL
standard
by more
than
th ree times
thanks
to
Tamron's
ori
ginal
coat ing
t
echnique employing a combination of
a single
layer
of metallic coating and two
layers of
high
molecu lar fi
lm
s.
(5)
Unique and Convenient Outer
Design
In designing the outer appearance of
the
lens, emphasis was put on
the
maximum
handling
convenience by concentrating
all
the necessary
in
formation
in
one
place where
it
can be easily read. Most of
Tamron
lenses,
including
your
new
lens,
are marked with the maximum
macro
magn ification scale to be applied when
Tamron's
SP 2X tele-converter is used
.
6
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