Computar Lenses

User Manual: Manual

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__
KYVYX
Oocaslonalty. wilen developing
n_
products II
Is
possible
to
be
too succassful.
as
we
were
with
the
251nm
.
Wa
wanted tha short·
..
t foeallangth lans posslblathat
would
ylald
excellent
parlor
·
inanc:a
over
the total
35mm
lormat
cornar to corner. and
we
got it.
But. since
no
one
has
had
prior
dllrkrc~"~
()Xp8
~
i(lnce
with ex·
treme
wide
angle
enlarg
ing
l'enl1l8.
we
ilOon dj.seoviired a
mS,Jr problem.
The
lens
was
too
ahort. Froln a praCtical standpoint .
It beC.me extremely difficult to
pilrform
nOrmal
corrective opera·
tlon.
auch
aa
dodging and burn·
Ing.
AlSo.
In
some cases It
was
vir·
tu.lly
Impossible
to
critically
loeu.
a negative with a fine grali,
magnifier because it wouldn't fit
under the lens.
so
we
opted for a
30mm
focal length instead.
This
type
of
asymmetrical
design does not lend Itself
as
an
all purpose lens.
The
Intentional
improved performance at
hlgto
magnification necessitates
pru
·
dent use at tha lower end.
I.
e.
about
10X
magnification
. This
translates Into
an
11
x 14' print
Irom a
lull
35mm
negaUve
or a
5 x
7'
print from the
110
formal.
.
dl
2.8/30mm
OPTIC:AL
_l.....
..
30
.
...
~
.....
......
..
.
ru
·u
.
.......
AIIII
..
.
12·
......
.......--
..
.
llx
Color
ConIc..
.
..
4"-7'"
...
,Fec:
.....
_
.
44
.
....
11--;-(1)
. .
RoopF
....
_
""""'
.
-Ig)
.......
50_
-,_
...
....
....
,.
. -(h)
......
..
lUlr
..
....
_
___.
-(0)
11.21_
_
..
-
UrIiJII
··
·
..
. _
••
C:HAMICAL
"'
....
l
.....
-Ia)
.....
71
.
511
•
..................
.
..
_ -.
Ib)
.........
II
.
S-
_
.......
-le)
....
41
.
...
_
..
_M"
TlIrUII
-Idl
.......
.. .
31x
1.1
_"_Cal
-lei
31
._
FIII<
.....
TlIrUII
-Ii) .. . 121 1.71
_"_I
Cal
-
(kl
51.'"
_I
..........
eoolnlo-
(I) . .
..
. .
II
.
S-
Acceptable
pri
nts
at
smallar
magnifications
are
obtainable but
only at the expense of raduced
apertures. A
4X
print requires AI)'
proxlmatety f:
11
aperture. but
since
the
negative
to
paper
dIstance
Is
only 9+
'the
exposure
Um
••
are
relatively short.
Even
though
we
Increa.e the
focellength
01
the lena to make It
more manageable. the Computar
30mm
Is
the ahorteat enlarging
lens
available
for
the
35mm
negative.
tn
comparllon.. with a
conventional
50mm
lens at the
same
projecllo
'" distance. the '
30mm
wfll
produc.
an Image
approximately 40';' larger.
AIIIO
at
equivalent projection distances.
the Computar
30mm
will Produce
an
Image about
25%
larger' than
the shortest focel length e"larg-
Ing lens available
to
date.
As
an
example. a full Irame blow·
up
to
an
11
x 1 .. ' print
requl~s
a
neg·
ative to paper distance of just
17·1t
' . or a
16
x
20
' In less than
2
..
••
while a huge
20
x
30'
print
needing only 26V
.·
can
be
pro·
duced
on
most
conventional
35mm
enlargers.
The
Computar
30mm
perfor·
mance characteristics
.re
similar
enough
to
the
25mm to
allow
using
the
previously
published
data.
OPTICAL
_t.erriII
.......
.. .. .. .
II.l_
A"",,,,,
. .
......
...
11.1-11
A
.....
fIroIoI
.
..
. .
....
...
..
41'
......
.......-
.
.. ..
.
l.x
'*~
............
411
-
7_
---
..
-,-111
..
........
..
I
..
...
.....
--
1I111or11y-(gl
............
41
.
...
-,_
..
-
.........
·
-lh)
.....
....
...
lu_
.....
_...-
-(i)
..
-12.'"
...........
l
........
. . . '
31.4_
••
CHAMIC:AL
_l
.....
-I·I
.
......
.
41.1_
.................
"_-(b)
.....
'
......
.
11
.
...
.......
_-(el
· ··
..
41
.
...
_
..
.......
T
....
-(dl
..
........
..
·lhl.l
_
.....
CaI-lel .. .
14.7_
__
TllrUll-Oi
.....
lI4hl.71
_"_Cal-(kl
.. .
47_
_
..
........
c.ot
-(II
.. ..
........
..
11._
The 50mm focal length has long
been considered the standard
work horse for. the 35mm format.
In developing I,
toe
Compufar 50.
special emphasi s was placed on
the
astigmati
sm and l
ield
curva·
ture. These are two major factors
that
contribut
e
to
the visually
apparent
ZOnal
problems. These
"soU
" .. reas on the. print ..
re
(j
ue
to
the negalive being out of focus
The Computar 50 possesses ex·
tremely good flat field charac·
tehslics
.
The
most
apparent difference
The
Computar
55
represents an·
other unique approach by rethink·
Ing enlarger lens requirements.
One is providing solutions
to
some
of
the vexing problems en·
countered
in
color enlarging, of
which the most serious is the
dilli·
culty
of
color
balance associated
with exte'ndetl exposure periods.
A real need exists
lor
a usable
high aperture projection lens. The
F/1
.9 aperture is the highest aper·
ture realistically obtainable due
to
the size
of
the Leica mount. shal·
low depth of focus and acceptable
containment
of
the aberrations.
The
Computar
55
is
one of the very
few lenSes available that permits
using the
F/2
.B aperture
to
Obtain
professional quality prints.
1\
should
be
noted
that
lor·
merly. when
making"
x
or
6 x
prints the
F/l
.9 aperture was not
usabfe because conventional tim·
ers were
not
fast enough
to
con·
sfstently obtain proper exposure.
but
wfth new digital timers ac·
curate
to
0.1 sec.
this
is now
posslbfe.
Another area
of
interest is that
of
utilizing the ffoating element
concept
to
oplimlze the lens for
any magnlffcation
from
.. x .
to
20
x .
It
is an optical fact that all
lenses
in thiS
le
n~
however.
IS
thai of
relative
illumination
. At the edge
of the format coverage the lens
exhibits
an
a
pertur~
efficiency
of 72
%.
In terms of relative illUm·
ina
ti
on
thi
s lepresents a marked
improvement over conventional
lenses. Combining thiS increase
in rei alive
illumination
with
its
extremely high transmisSion
characteristics produces a gen·
eral
Illumination
effect
that
is
abSOlutely startling. Suddenly
brilliance has a new meaning.
OPTICAL
FtcIIL
...
. .
..
. .
14.I_
...........
....
.
IfU
-12
AfIIorIIr
AlII! . . . ,
.'
43"
g
.,...
............
....
4x-Zlx
C.CMMIIII
........
-7_
-,......
.
..
....,-(f)
..
..
.
..
...
......
,..-.-
..
....,
-(g)
....
,
....
2_
....
v
....
.....
.....
1'1.-(1\) . .
...
. 14
....
..........
.
........
-(1)
.•.
• -11.2
..
v
....
v
....
......
...
..
......
47
.
~
UCIIA-.cAL
.....
LIiIIJI!-(a) • •
I4.3-
....
......
............
-tbl
..
l1
....
............
-(el
....
....
.....
4
..
...
.................
nr..i
-
(dl
..
.....
11M
1.1
...........
CII-(.I
....
.
......
..
7"
........
TInIoI
-III
....
........
..
IMIx
U'
......
..
,...CII
-(kl
........
..
...
.
1.1_
...............
c.w-(II.;
..
.
..
II
....
foxed
tocal length projection lenses
will suffer image degradation when
used at any magnification
other
than
its
design optimized value.
Some designs degrade more rapidly
than others. The floating element
optimization technique definitely
im'proves .the lens performance
over
the large magnification
range$
.
Even
though the upper optimiza-
tion
was
limited
at 20
x,
higher
magnifications
wili
stili
be sub-
stantially improved'.
The floating element is also a
beautiful device for filiaf "twEiak·
ing" of the image; either for bringing
it alf together or selective zone con·
trol.
as
the various zones can pur·
posely
be
defocused
..
An additional bonus. not
often
considered. is the short depth
of
locus of the F/l .9 apertllre provides
an excellent enlarger alignment
tool.
The net
r~sutl
is for the first
time
a lens is available that can be tuned
by the vperator to solve his specifiC
problem whether
it
be
utlra
fast
exposure times. unusual
effects
.
or
the capabi lity of producing beau-
tiful
mural size color prints directfy
from the original.
COIIIpUtar.
vaifacal
SO-80
4.5150
to
5.1I8Omm
from
35nwn
to
6x7cm
tonnat.
Varlfa
50·80
MIt_nU?
The
v.rlfo
'
c.'
50·80
covers all film
fermats
up
te
and
including
the
6x7cm
(2
V. X 23("'). At the 50mm
local
length
setting
~he
lens is .optimized
to
cover
the
35mm
format
, whereas at the 80mm
setting the lens covers the Sx7 nega·
tive.
These respective settings yield al-
mest the same
print
magnification
vs
.
working
distance
as
normal
fixed focal
length
lenses.
The lens is
continuously
usable
threughout
the entire range from 50
to
80mm. Example-the
complete
SxScm
(2
V4 sq.) negative can be projected at
between the ·
SOmm
and ·the 70mm set·
ting. ·dependent upon prejected mag-
nification. This capability is equivalent
to
some
.of
the
"wide
angle"
lenses in-
troduced ever the past several years.
By selecting a short focal length. the
le
·
ns
will
permit
unusually
large
blewups frem
the
central area
of
large
negatives. Similarly, due te a
functien
of
fecal length
vs.
magnificatien op-
timization. a
leng
focal
length
will pro-
duce exceptional 4x5'" prints.trem the
35mm
format
Another possibility-set the eAlarger
head at the
preper
height
that yields an
8xl0"
print
from the 35mm negative
with the 80mm fecal length, then by
"zooming"
up
to
the 50mm position
the image is enlarged
te
a
13"
x
20"
.
This increase is
quite
sullicient
for
normal
crepping
and compesing re-
quirements.
As
long as
the
negative
to
paper distance .is unchanged. the ex-
posure
for
any magnification is pre-
dictable once it has been established
semewhere
en
the fecal length scale.
Once
the
exposure is "zeroed
in"
at
~
..
..
'4·
ex
30
12
- 8
26 10 - 7
22
8·
5
18
6·
3
,.
••
2
13
"""CAL
Foc.'
..
"....
.
.......
13.2
to
71.11M1
.......
,.....
.
...
,
flU
.....
tDl2
........
,
.....
....
.......
......
W
..
..
~~
....
.....
101
..
h
c.e........... . .
...
-
r-..
---
·......,
·M
--
..
......,
.(
.....
,...,
..
,...
....
.........
.JIMt
..II.JntM
..
n.a ....
...........
lpt.(t)
••......
...
'
.......
tD7.a-
NocIIII
....
nt_
........
-c.'
.21.1_.1U_
V
.....
v.r..........
. .
.........
17
......
-
=:.~~~tbJ·::::
:::::=
.........
_
..
........
......,·(c}
....
....
lIal.O
...,..,..
tIWUd
-
III)
••••.•
...,
ri
t.7'
_
..
--....
.....
·
..
.
.......
. a ___
anyone
focal
length
position, then ex-
posure adjustment becomes predicta-
ble
for
the
ether
focal
length
settings.
Assuming similar negative densities,
one can
new
individually
crop
and
print
complete rolls
of
negatives much
faster than previously possible.
50 0
+1/4 +1/2
+2/3
60
-114
0
+1/4
+112
70
-112
-1/4
0
+114
80
-2/3
-112
-1/4
0
CHANGE
IN
STOPS FOR CCRRECT
EXPOSURE· ASSUMES CCNSTANT
NEGATIVE
TC
PRINT DISTANCE
Varllocal
VI.
lOOM
A
high
quality
zoom prejectien lens,
will theoretically stay in focus
as
yeu
ch~nge
the nlagnification. however.
they are designed
to
cover only one
specific format. i.e. 35
or
6x6. Unfertu-
nately, they have a tendency
te
beceme
physically large, expensive. and
not
nearly
as
versatile as a
v.,lf_
•••
Instead
.of
· just
.one
format,
the
v.rtf_
••
has
multiple
format cover-
age capability. This type
of
lens does
experience a. fecus
shift
as
the
lens
Is
run
through
the
fecal range. If
the
en-
larger is locked at a
24"
prejection
dis-
tance (negative
te
paper) the lens
will
preduce
a fecus
shift
of
approximately
I "
as
the lens is changed
frcm
50mm
te
80mm. While changing the lens focal
length
with
one
hand and refocusing
the enlarger
with
thli
other. one
ca'n
lenses
. corqJUIar-
vaifacal10S.1SO
4.51105
to
5.1I15Omm
ftom
6x9cm
to
4x5"
formats
closely
approximate
an auto
focusing
system.
The focus
shift
, itself, represents a
very desirable feature
as
it can be
utilized
for
fine focusing. Instead
of
try-
ing
to
.obtain that
critically
sharp image
with
enlarger
focus, simply use the
lens.
It
has a smoother, more
controll-
able
motion.
in addition
te
being closer
te
the
easel and therefere more
com-
fortable
to
manipulate.
Varlfoclll05·150
A
professional
quality
tool
fer
the
cus-
tom
and
exhlbltlen
printer.
The
105-150 mainfains all the desirable
capabilities
of
the 50-80; however, the
most important and far raaching aspect
of
this lens is that
now
-photographers
have been given "zoom" capability for
the 4)(5" format -on both the enlarger
and
the view ·camera.
c.ra
.....
The 105-150 may be meunted on a
view camera using available adapters
and the
#3
shutter. With the addition
.of
a special mounting bracket -the lens is
turned
into
a functional zoem. The
limiting
factor is the capability
of
the
105mm fecal length
te
cever
the
full
4x5" format. Experience has shown
that, if! mest
preduct
photegraphy and
closeup situations.
this
is not a serieus
preblem. This is due
to
the increase in
image si
ze
as
the lens approaches the
subject
In
terms
of
perspective and the
field
of
view. the
v.rlfoc
••
l05-150 e·n
a
4x5"
would
be
equivalent
to
a 30-50
zoom
for
the 35mm SLR.
Even
if
the zoom
motien
is not a re-
quirement
.
The
quick
composing
capability when used
fer
product
photoQraphv eliminates the necessity
of
excessive
tripod
shuffling. This
~
....
9 .
ex
..
8 · S
'0
7 •
36
8 • 4
3.
S . 3
28 4 • 2
2.
3 . 1
20
18
The magnification below 150mm
re~
re.enu
tot.,
41:5
" lormat coyftfaga.
Th.
value below 105mm repr
...
nt.
m-onifl-
cation,
but
nOI
necnsarily
the
complete
forma
t. The
l05mm
CO"I'II
tha
".5
"
.t
1:1
do
wn
to
tha
ex9cm
al
infinity.
With
the
neglillM
10
p
ri
nt
di'l
t.a
n
c.
al 48",
the
ma
xim
um
ob
tai
nabl
a
maQnlt
i
catiDn
of
Ihe
full4lt
S
format
is
7.5x
~
I,jli
ng
the
13Smm
fo
car
lanoth
setting
,
OPTlCAL i
foe.l.....
..
.
.....
'
..
. 7
......
'IO.&.
I
~r~
••••••
114
.
.......
22 j
,.,....,
....
..
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........
.....
...
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............
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tot
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---
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1-.
. ..,,,
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C.)·
...
'ao.'
.....
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,..
...
v.... •
......
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__
I,.
· C .. ···········J, ..........
,:U
..
'"
NodIaI,.....~·I
..
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........
I1
.
....
VtIrth
..
V
...........
"
....
111.1
__
n .7 _
_ CIWIICAL
0NreII
.......
.
,_,
.•••
•••.
••
"'
.............
~
........
(It}
••••••••
n...
"'_of
...............
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..........
u
....,
.........
,,)
......
...,
...
,.
_
..
.artt.c.I~
."
........
.,...
saves considerable time. while insur-
ing selection
of
the
best cempositien.
On
tile
Ell.,..
It is
now
pessiblete
produce
"zeom"
prints
frem
straight
negatives.
Older
negatives can be used
to
produce
new
images. Specialty shots that require
telephoto
.or
wide angle .objectives can
ultimately be presented in motion. And
the ultimate -
"zoom
on
zoom"
-
once
in the camera and again in the dark-
room.
For
Speclel
Effects
• Add and blend colers.
• Increase the zoom range and
accentuate the
motion.
• Spiral
the
image-retate
the negative
or
easel
while
zeoming.
•
Multiple
expesures at
different
magnificatiens.
The
verl'ocall05-150
cen
be
•
P,obie"m
Solver for the pro
In-
~
ADVERTISING-quickly
and
easily
obtain
exact
magnifications
either
on
negative
or
print.
~
PORTRAIT
_asily
vary
print
sizes
from
one
negative
'rom
8)(10
down
to
wallets.
~
COMMERCIAL-short
on
time-straight
shot in field &
"zoom"
in
darkroom
'.
~
A.V
.
-meiling
of color. produces
unusual backgrounds lor typography.
-exact
sizing
for
multiple
"
drop
in
"
images on one frame.
The
compula,
v.rtfoc
••
e will
add new and creative dimensions
to enhance existing photegraphic
techniques and capabilities.
©
1"9
Burtoigh
B_
()ptico
,
Inc
.
All
RIgh
..
R_
computar
dl
5.6/135mm
OPTICAL
Focll
llngtll .
..
.
.. ..
...
...
135.1mm
9
'A"~u"
Ringo
. .
..........
US.&·22
Anguli'
Rolli.
. . . . . . . . . . .
..
&0·
Optimum
Mllnlftcltion
..
.
...
fi.
Cola<
CorrecHon.
. '" .
..
.
..
400·
700nm
I t Blck
FoCUI
DlltlnCt
'
"llntInlty
-
(f)
.
..
.....
....
110.&mm
ftantI
Focul Distinct
II
infinity
-(g). . . . .
..
. . .
..
122.1m
..
'~
,
:
r.e
tr
~
:
t
r;
F
B
S
~
r
')t
;
"a
h
~
.
tai\1
tn
g
the desirabie Leica mount capa·
bility, the Computer
135
was
da-
signed
as
an
1/5.6
aperture. This
reduced
effective
aperture
en·
abies the lens to provide excel·
lent ,elall
ve
illumination charac·
!er!s
Nocs
wnile still maintaining
m
a,
'agea
lli
a clear apertures.
rhi
s
lerlO
was developed to
be
lhe
short.est iocal length that is
practical for t
he
4'
x
5"
format.
The lens is nominally optimized
for
6x
magnification. This pro·
·,
[des t
he
IJs
er the capability of
making exceptIonal print;;, from
B
x.
10
or<Jofs
'
!JO
to wall size
murals
."
.
Liberal use of high index low
dispersion glass has produced a .
lens wi th
an
exceptionally high
·\legree 01
'~
n
l",
(:orrection.
_Vlltlll
...
.
_1'1
.
-(h
I
.....
. . . ,
..
.
U5m
..
, _
PoI.,
Se""ro1ien
-(i) . . + 2.3
....
V_
I "
Vertel
t...,...
. . .
..
45.'1
..
m
••
CHAIIICAL
"'
....
l...,.,
-
(al
....
,
...
41.S
....
""Ung
Sarf""1
..
.,
.
• f _ - (b) .
..
..
.
......
12.0
....
IlIlm_.f
8orre!
-
(el
. . . ..
41m
..
IlIlml'"
If
MounHng
Th
.....
-(d)
.....
..
......
3'"
1.0
IlIlml1l,
If
RII'
Cell
-(e)
...
37.0mm
Allor
Sc
..
w
n,,"d
-
01
....
, M43. 0.75
IlIlmllor
If
FlOnl
CoU
-(k)
...
47.0mm
DI
......
'
Qf
OI."hragm
ConI
...
-
(I
I . . . . . .
..
5Umm
is very important from the stand·
pci'll
of eliminating the necessity
of
compromise fpc using for the
difference in field zones. Most
typical lenses overcome this defi·
ciency by requiring the use of
smaller aperture stops and, con·
sequentl
y,
long exposure times.
The third area
of
importance is
that
of
transmission. The 135mm
design approach lends itself very
nicely to the Computar
UV
sup·
pression techniques. This capa·
bility is essential in providing
superior blacr, and white and
color prints.
!
~
}
(?,(?
~
~~
r
~it;
l
)i~
r
~t
tg
n
ti
on
was
I devoted '10 tM field flatness. This
Many lenses will make accept·
able
30'
x
40
' prints when viewed
at a distance
of
4
or
5 feet. The
135mm Computar has the capa-
bility
of
making exceptional prints
that sti
ll
stand up under very .
close
in
spection.
~
TECHNICAL
INFORMATION
AVAILABLE
Our~24page
color brochure utilizing hun-
dreds of charts and graphs
relates concepts like MTFt
OTF,
Vignetting, etc. on a
practical basis
so
lenses can
be selected, analyzed and
used
with
knowledge
and
confidence.
enlarging
lenses
lense:
SO-80
for
35
to
6x7
1
05-1
SO
for 6x9 to 4x5
FOR THE RRST TIME,
AN ENLARGING LENS
HAS BEEN DEVELOPED,
THAT WILL CHANGE
THE CLASSIC VIEW
OF DARKROOM OPTICS.
THESE LENSES HAVE
THE ABILITY TO REPLACE
MOST, IF NOT
ALl,
OF THE NORMAL LENSES
BE
~
NG
USED TODAY.
ADVANTAGES
• One
lens-instead
of many.
• Eliminates changing lenses and condensers.
• Eliminates turret systems.
•
Color
balance only one lens.
• Easier and faster
to
visualize
cropping
possibilities,
• Produce
"zoom"
prints from straight negatives.
FEATURES
• Variable
format
coverage.
• Continuously usable
throughout
total focal length range.
• Large magnification variation immediately available.
• Minimal aperture stop variation
throughout
total focal length range.
• Smooth and accurate
click
stops at half step intervals.
• Super critical
focusing
capability.
KYVYX
The
Computer
65
lor the
35mm
double Irame lormat
Is
quite
prob-
abfy
the
IInest IIxed local length
enlarging lens available
today.
By
utilizing a smaller field
01
view
In
a longer loeal length
lens,
the
desigfMIr
has
the ability to
con-
trol the various aberrations to
an
exceptionally high
degree.
Spherl:
cal aberration Is Improved to the
extent that lurther reduction
In
the
lens aperture
does
. not appreciably
Increase the optical performance
of the lens. This is one of the lew
lenses that realistically can
be
used wide open.
The
Computlr
90
la almply I
IClled
verllon
of
the
IIOmm
CGIIIputar design. Other than
r.
optimizing the
lena
at Ita partlcu·
Iar
focal length,
we
dllCOY8l'ed
that
we
could not Improve upon
the IIOmm'l dealgn performanca.
Thll
lena retatnl all of the qual·
ItI
..
that make the
eomm
excep-
tlonalln terms of color correction,
flild flatn
..
1 and
utlgmatllm.
The Compu
....
90
can
be
utI-
OPTICAL
..........
........
.. ..
........
.......
..
..
......
.....
11
......
I'11III
..
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......
.
.....
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....
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v
....
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I7
.
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....
ItV
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HCMA.ICAL
.......
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-(a,
.
..
,
.....
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...
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-(b)
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....
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....
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The
lens exhibits
an
unusually
superior flat field without
any
focus
Ihllt
when
the lens Is closed
down.
The
special attention devoted to
the chromatic Characterlstlca
has
reaulted
In
the unuaually high
r.
aponse
in
the higher frequency
renges.
We
feel
we
have
achieved our
goal
In
creating
an
extraordinarily
high quality
lena
on
a production
ball.
The
85mm
CoIIIpuIer
la
dell-
nltely
lor
the perfectlonlat·
Who,.
quires the ultimate in reproduction
capabfllty.
OPTICAL
............
......
..
....
..
1_
...............
....
....
.
..
11
.....
I'11III
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...
....
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au..
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..........
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.............
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=~~~
......
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...
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..
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...
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............
..
U.IM
IIzed either u a
lhort
focal length
lenl
for the 8 x 8 format,
or
an
excellent
8 x 7 proJection
lenl.
Generally, the 90mm lena
hu
been conlldered I
fll*
between
the more popular focal lengthe
and
not really meant
to
IOIve
any
particular requirement.
WI
hope
to
hevechanged
thll
concept by
supplying a
lenl
with superb
0p-
tical performance up
to
and
In-
cluding the 8 x 8 cm format.
From the standpoint
01
optical
dea
lgn, this
has
been
a
very
int.er·
astln.g lens development.
The
dealgn form is relerred to
as
a
plaamat or a second order gauss
which Is the conventional design
type used
in
the longer focal
length enlarging lenses.
The
Computar approach
in
solving
$Ome
01
the specifiC problems
are
readily apparent.
Comparing the optical sche·
matlc against "typical" lenses,
will Immediately indicate some
rldlcal departures.
These
are
in
the form
01
glass thickl1ess,
.shapes and types. Immediately
apparent is the unusual
un·
aymmetrical apPearance. This
The Computer
105mm
is a con·
tlnuatlon In the
80
, 90
deSign
aerlea.
WIt
have
maintained the
60
degree field
01
view, which
en
·
ablea the lens to overcover the
Ix9cm
format
by
15%
.
Although the design Is ' optl·
mlzed at
6x
magnification, It pos·
seases a great latitude
In
extend·
lenses
O~TICAL
fIuIl
.....
. .
....
......
. . " .
2_
~
....
...... ...
.
..
....
·
11
A
.....
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......
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......
..
.
....
.
......-
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.....
.
c.rClnlctlo
.......
.
....
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..
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..
......
..
...
1.1_
:':"~I~
..
.
....
11
._
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.....
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.........
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..
........
..
17
.
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.....
...
.....--111
·· - . .
...
v
......
V
....
lIefIo ..
...
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11
._
..CHANICAL
.....
lIIIIIfI-(·}······.··
......
.....
......
...
.......
-(b}
..........
..
t."
.......
.......
-(c)
...
.....
...
.......
..
......
TInII-(d)
..........
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..
H.1.I
.........
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..
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...
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.. ..
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..
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..
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'2.'"
appearance is a result of our el·
lorts in deriving unparalleled
color correction
lor
this type of,
design. Combining this with the
drastic reduction
01
the· oblique
spherical
abe
ration has 'resulted
In
a lens with exceptionally high
contrast in the middle spatial
Ireauencl
es.
This particular dealgn
haa
su
o
perb capability over
an
angular
field of
60
degrees. For the Comp-
utar 50, this tranalated Into a 6 x
7cm
coverage. These refinements'
were
polslble
even
thOUgh
we
maintained th8
114.S'
aperture.
The
4.5180
II
the lasteat 6 element
large format enlarging lens avail·
able. Truly a
un
ique lena.
~TICAL
fIuI
......
. .
.......
.....
1
..
.
2_
........
...
..
......
.
VU·22
.....-
..
..
.....
..
...
..
.
.............
....
....
c.r
CInIctIo.
.. ..
..
..
...
•
..
.
·7_
...
...
-..-
......,
- .
(1)
....
...
....
..
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...
:.:.,~(~
.......
13
.
...
..._.-
.....
"'-(I!)
....
.....
...
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.
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......
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•
.....
v_
......
..
...
.... ...
..CHANICAL
.....l
....
-(.}
........
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...
.......
_.-
........
-lb)
..
...
....
...
11._
.......
.......
-(c}
.
....
...
...
.......
..
......
TInII-(d}
.
..
....
......
IDIK
1.1
_
.....
CIII-I.)
...
11-'-
.
....
_l1IIIII-U)
....
.
1IU.'
.
11
_"FnoICIII-(k}
....
,
....
-
...........
CIIINI-(I}
....
..
......
..
N."'
.
ing the usable range from 2 to
12x
.
The
additional advantage of the
114.5
aperture will become
In
·
creasingly more important
as
color enlarging continues to gain
In
popularity. Unquestionably one
01
Ihe finest lenses available
lor
the 6 x 9cm format.

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