Durst AC1200 User manual

Durst AC 1200
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Operating manual
bJ'd[2i eClZQQ
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With the Durst AC 1200 you now own a Quality pro-
duct made by Phototechnik GmbH, offering the high-
est standards of precision and workmanship in ma-
nufacture and QualIty control.
With its
rel iable
you well
exceptIonal convenience in handl ing and
operation this top-class unit will serve
for all color enlarging.
Successful performance however also depends on Cor-
rect operating procedures. This systematic manual
therefore explains both the assembly and the opera-
tion of your enlarger.
Please take the trouble to read this
roughly. Complete familiarity with all
tions and controls will ensure that
annoying failures or even damage.
manual tho-
the opera-
you avoid
Durst Phototechnik GmbH, Bressanone, Italy
Studio Durst GA IV 30015 (e) 10/85
1

Contents
Description of the enlarger
- The outfit
- Unpacking and checking components
- Space requirement
- Assembling the basic enlarger
- Fitting the tungsten-halogen lamp
- Fitting the lenses
- Fitting diffusor with holder
- Fitting the mixing boxes
- Fitting the negative carrier
- Wiring up
Lens boards and barrels
- Attaching the desk illumination
- Connecting a roll paper easel and
FEMOWAL N wall mounting
- Working with a roll paper easel
- Functions of control unit
- Schematic representation of the Durst AC 1200 system
- Short explanation of structure and function
of color materIals
- The six-part color star
- Schematic rundown of an exposure
- Description of basIc filtration functIon
Page 4
page 4
page 8
- BasiC memory "cal"
- Paper slope "X.Comp" (=Time Compensation)
- Reciprocity faIlure
- Full-area metering method
- Low correction for color (LC=Low Correction)
- How does the low correction work?
Overriding color and density corrections
Manual timer operation
- Exposure counter -
2

page 24
- Integrated readings
- Spot readings
G) ~cQ9cQmmin9 ih~ Q~c~i BC 1200 £QC ~Q1QC n~99ii~~§L page 25
color transparencies/black-and-white negatives
- Carrying over programming values
- Detailed descriptions and notes on some steps of the program-
ming instructiones
page 42
- Production prints
- Working with low correction
- Working with automatic density control and fixed filtration
(VXFF)
- Dodging
- Working in the manual timer mode
- Visual correction of the processed test print
page 45
page 52
- Production prints
page 54
page 55
page 56
page 59
3

Description of the enlarger
The Durst AC 1200 is a universal microcomputer-controlled color enlar-
ger for color and black-and- white negatives as well as transparencies
of all sizes up to lox12,S Cm (4xS inches).
The negative or transparency is metered (choice of integrated or spot
readings) on the projection plane with the aid of a probe before the
exposure. All further operational characteristics are described in sec-
tion "C") Operating functions" on page 8 of this instruction manual.
The outfit of the Durst AC 1200 comprises:
- the basic enlarger consisting of the enlarger head with column,
column base and baseboard
- the COLIDESK 1200 control unit
- the POWER 1200 power unit
- a COLAMP 250 tungsten-halogen lamp
-
COFEMNEG negative carrier with FEMOGLA AN anti-Newton glass and a
lower FEMOGLA film carrier glass
- one mixing boxes FEMOBOX 450 N, mixing box for 10 x 12,5 cm (4x5
in.) fi1 ms
- one pair of maskes FEMOMASK 450 for 10 x 12,5 Cm (4x5 in) films
- mains supply and connecting leads
- test negatives
Unpacking and checking components
The Ourst AC 1200 is shipped in a specIal protective box. Please check
that all components of the outfit specified are included and
undamaged. Before assembly carefully clean all parts.
Space requirement
The Ourst AC 1200 has been designed to take up minimum operating space
(100 x 100 Cm or 40 x 40 in.l so that it can be located on a bench in
any darkroom or mounted on the wall for use with roll paper easels.
Assembling the basic enlarger
Place the column (1) and column base (2) with the enlarger head stage
on a table so that the column base protrudes beyond the table edge.
Hold the baseboard (3) against the column base and - using the spanner
(5) suppl ied -SCrew the five hexagonal bolts from underneath through
the baseboard into the column base,ensuring that the reiforcing plates
(4) are first fitted beneath the baseboard. The column carries
magnification (6), centimetre (7) and inch (8) scales to faci 1 date
resetting the magnification for repeat jobs. Fully raise the enlarger
head stage (9), mount the color mixIng head on it and secure with the
six thumbscrews (10).
Ll

Fitting the tungsten-halogen lamp
To fit the lamp (11) press the locking button (12) and remove the
lamphouse cover (13). Inside the lamphouse you ~ill then see a retaI-
ning strip complete ~ith retaining springs. Mount the tungsten-halogen
lamp (11) on the lamp fitting and push it underneath the retaining
springs. Take care never to touch the inside of the reflector ~ith the
fingers.
Fitting the lenses
Scre~ the lenses fully into the appropriate lens board or lens
The lens board or lens barrel holding the lens IS then engaged
3-point mounting of lens support (14) and secured ~ith the
screw (15) so that lens aperture values can be seen from the
Lenses as well as lens boards and lens barrels required for
the lenses are available as accessories (see page 54).
barre 1.
in the
locking
front.
fitting
Fitting diffusor ~ith holder
To fit the diffusor (16) first push the shaft (17) into the appropria-
te opening of the lens stage and secure with locking scre~ (18).
The diffuser must be moved up and do~n the shaft so that It Comes to
rest underneath the lens (diffusor/lens distance approx. 1 cm), where
It is secured with locking sCrew (19). The connection lead (20) is
plugged into socket (21) on the enlarger head.
Fitting the mixing boxes
Push the mixIng box required with the four hexagonal studs (22) into
the cutout in the catches (23) underneath the color mixing haed. The
catches must be in their forward position - pull them Torward If
necessary. Once the mixing box is in position, push the catches back.
The enlarger is suppl ied complete with the FEMOBOX 450 N mIxing box
for 10x12,5 cm (4x5 In.) films. The following mixing boxes are availa-
ble
as
accessories:
BIMABOX 35 N
for f i 1m
sIzes
up
to
24x36
mm
BIMABOX 66
N
for
f i 1m
sizes
up
to
6x6
cm
(2
1/4x2
1/4 in. )
BIMABOX 69
N
for
f i 1m sIzes
up
to
6x9
Cm
(2
1/4x3
1/4 in. )
Important: The FEMOBOX 66 N, 69 Nand 450 N mIxing boxes are supplied
With an additional, less dense diffusing sCreen. This diffUSIng screen
can be used for shortenIng exposure tImes when prIntIng film originals
which do not require perfect color miXing.
To replace the FEMOBOX 450 N diffusing screen, the inner mixing box
must first be removed from the box. The diffusing screen can than be
taken out and replaced by 1 ifting the springloaded retaining strips.
On FEMOBOX 66 Nand 69 N the retaining strip of the bottom diffUSing
screen IS taken off after undoing the two FEMOBOX 66 N) or tour (FEMO-
BOX 69 N) screws, after having removed the mixing box from the box.
Now you can fIt the less dense diffusing screen and re-assemble the
mixing box.
5

Fitting the negative carrier
Push the negative carrier fully into the enlarger head. until the two
pressure springs (25) behInd the locking bolt (26) are engaged. The
negative carrier is supplied with a FEMOGLA AN anti-Newton glass In
the upper section and a FEMOGLA glass in the bottom negative carrier
section held in place with the aid of retaining springs (27). For
glassless enlarging of the 10x12.5 Cm (4x5 in.) film size the enlarger
is suppl ied with the FEMOMASK 450 pair of metal masks. The following
pairs of metal masks are available as accessories:
FEMOMASK
92
for
f i 1m
sizes
9x12 cm
FE MO MASK
69
N
for f i 1m
sizes
6x9
cm
(2
1/4x3
1/4
in. )
FEMOMASK
67
N for
fi 1m
sizes
6x7
Cm
(2
1/4x2
3/4
in. )
FEMOMASK
66
N for
f i 1m
sizes
6x6 cm
(2
1I4x2 1/4
in. )
FEMOMASK
45
N
for f i 1m
sizes
4.5x6 Cm
(1
3/4x2
1/2
in. )
FEMOMASK
35
N
for
f i 1m
sizes
24x36 mm
FE MO MASK
S
for
all
further
DIN and A$A
f i 1m
sizes
For printing roll film sizes up to 6x9 Cm (2 1/4x3 1/4 in.), the spe-
cial ROLLFILMNEG 1200 negative carrier is available as an accessory
(see "Accessory range" section on page 54>'
ltJicin9 ~~
To establ ish the electrical connections. plug in the leads as shows In
the diagram below.
AC 1200
Rollpapereasel
.:;:
o
~ +..:...H""o",-in:.-_uZ.
P~r
1200 EPU
Diffusor
6

Lens boards and barrels
The following lens boards and barrels are available as accessories for
fitting various types of lenses and different focal lengths:
LAPLA SO
LAPLA 42
LAPLA 39
FLARING
SETOPLA 2839:
FEMOTUB
for lenses with M50 screw thread
for 100 - 150 mm lenses with M42 sCrew thread
for 28 - 135 mm lenses with M39 screw thread
reducing ring to fit lenses with M25 sCrew thread into
lens boards and barrels with M39 sCrew thread
for 28 and 35 mm lenses with M39 screw thread or for SO
mm lenses (M39) when using ROLLFILMNEG 1200
for 1:1 work and reductions
Attaching the desk illumination
To make operation more convenient, the enlarger can be equipped
the OESKIL AC control unit lighting {to be ordered separately).
screw the two crosshead sCrews at the red of the control unit and
these to fit the light. Plug the lead into the socket provided.
with
Un-
use
CQOo~~iio9 Q CQll ~g~~C ~g§~l 90~ EE~Q~~L ~ ~gll mQ~DiiD9
~or enlargements on roll paper the Ourst AC 1200 can also be used with
a roll paper easel and in this case mounted on the wall - without the
baseboard - uSIng the FEMOWAL N mounting available as an accessory.
<Check the Durst FEMOWAL N instruction manual). The Ourst AC 1200
control unit can be placed either on a bench alongside or on an
accessory stand (order code: STATIV COLIDESK 1). Locate the EPU 1200
power unit next to the stand on the floor or next to the control unIt
on the bench. Connection between the roll paper easel and the power
unIt is establ ished by fitting the roll paper easel's lead into the
appropriate socket at the back of the EPU 1200 power unit. Upon
connecting the adapter cable, it is possible to control both enlarger
lIght and exposure functions from the easel (if available on the roll
paper easel). The exposure can be triggered with the accessory foot
sWitch <order code: MAGIPE). The paper is advanced automatically after
the exposure.
~QckiQ9 ~iih gCQll ~g~~C ~g§~l
If a roll paper easel is used with the Ourst AC 1200, its operation
depends very much upon the kind of roll paper easel. You should
therefore check this with the Service Department of your country's
Ourst Sole Agency.
7

C) Operating functions
Contro 1 un i t funct ions
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20
-
e-,_
u:;, , l.CJ
"- L YJl,F'P
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21
101d
QIOll.J1
~
I
18
19
17
.-....--
J
~Dursf AC 1200
3
DOlQJ-
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I
rREC~OER 1
1- -- oqqqqqo.o.o,O,o,O.o.0'o.o ·.UO_
s...<. 1 1 .. •& ].J •• u.
r+---+--8tF~"-<-,, ;;
I
SI 710 65
1) LED rows IndIcatIng exposure tImes for the three primary colors
<y, M, C)
2) "Recall" and "Store" keys are used for recordIng or reading in
program on magnetIc tape cassette
- Pressing the "Recall" key activates the "Fine adjust" function.
This functIon enables you to read off exposure times for the
three primary colors (y, M, C) on the display (range goes from
0.1 up to 19.9 sec. and from 20 up to 199 sec.). Works only if
enlarger lIght IS sWItched on.
- The "Counter" IS activated by pressing the "Recall" and "Store"
keys SImultaneously. The display shows the number of exposures
made (to be read off from top to bottom).The counter range goes
from 0up to 9999 exposures - without the posslbil ity to reset
the counter to zero. (0 = 1, C= 10, M= 100, Y= 1000).
3 ) DIg It a 1 d is p1 ay f' 0r b1ue / y ell 0 w, '3 r e en/ m age n ta, red / c y an, de r, s It y
4)
PaIrs of keys for blue/yellow, green/magenta, red/cyan
S) Pair of keys to select memory channel
6) DIgital dIsplay IndIcating memory channel (0-9)
7) "Enter" key
8) "Expose" key to trigger the exposure

9) "Light" key to switch the enlarger light on or off and to inter-
rupt an exposure rundown.
10) "W.Light" key to engage motor drive to swing filters In color
head out of 1 ight path
11> "Sample and Hold" key to trigger a metering sequence.
12> Row of keys to indicate, change or enter recorded values:
- "Cal" key = basic cal ibration
- "Di ff" key to actuate the automat ic swinging-in of the diffuser
- "X.Comp" key = paper slope and reciprocity failure compensation
13) "Print" key = printing mode
14) "Timer" key to swItch to conventional timer mode
15) Row of keys to select operating mode:
to work in conjunction with a video color negative
-"VCNA" key
analyzer
"Neg" key =
"Pos" key =
"B/W" key =
Operating
Operating
Operating
tives
mode
mode
mode
for
for
for
printing
printing
printing
color negatIves
color transparenCies
black-and-wh!te nega-
16) "Corr. Hold" key = To retain correction values for several expo-
sures (without having the former erased after
the exposure)
17) "LC1" key = 1st low correction stage (75" low correction with ne-
gatives and transparencies)
18) "LC2" key = 2nd low correction stage (50" low correctIon with ne-
gatives and transparencies)
19) Pressing the "LC1" and "LC2" keys simultaneously actui:tes the
"LC3" low correctIon stage (LC3 =25% low correction wlth ne'3ati-
ves and transparencIes)
20) "Panel L." key to switch on or off all displays
21) "VXFF" key = The f i 1 ter ba 1 ance of the prev i ous exposure is kept
constant and used for the follOWIng exposures but
the film original's denslty changes are taken into
account and compensated
9

Schematic representation of the Ourst AC 1200 system
250 ~att/24 volt tungsten-halogen lamp
film original (negative or transparenCy)
IR-filter (heat filter)
dichroIc filters for basic filtration
(filter pack)
dichrOIC printing filters
1 ight mixing
top light mixing box
printing paper
lens
bottom (interchangeable)
box
meter! ng cell
0---------+--
= ---/-------
~ }--+-------
~ }--t-----_
OP:---r--~
O--+---
Metering probe
Characteristics of the dichroic interference filters in yellow (Y),
magenta (M) and cyan (C) used in the Ourst AC 1200 enlarger
In the Ourst AC 1200 three each (Y, M, C) high-Qual ity interference
filters are being used to provide basic filtration and automatically
controlled printing filtration. These filters excell through their
sharply defined transmission ranges.
The dichroic Interference filters for subtractive exposures in Y, M, C
have the characteristiC of reflecting one third each of the white
light spectrum (made up by blue, green and red) as sho~n here below:
Whde light
Blue Green Red
~rl
y ~ 110 \·1 fi1te ~ (Y 1
While Light
Elue Gre~n R~d
19r('e~
Hc9cnta filter (M'
l<lh i t. eLigh t
Blue Green ReJ
Cyan filter (C)
'----y-"
Ye 11 ow
v
MagentQ
"---y---J
Cyon
10

DIchroic interference filters are heat-resistant and do not fade.
Short explanation of structure and function of color materials
Special graphic arts techniques excepted. all current photographic co-
lor processes are based upon subtractive color mixing and the use of
three-layered material.
Subtractive color mixing is achieved in all calor materials.
regardless whether they are transparencies, negatives or opaque
materials. by superimposing the three seCondary primary colors yellow.
magenta and cyan. All materials are made up by basically three layers
~hich, depending upon the exposure having taken place previously, have
varying degrees of yellow. magenta and cyan color contents. All other
color hues are obtained by combining these subtractive primary colors.
For this it does not matter whether the 1 ight is transmitted through
the film base, negative or transparency. or whether it is reflected by
It (opaque materIal),
White Light
blue-sensi-
Yellow ti ve
green-sen-
:-iogento sit i ve
red-sensi-
Cyon live
If)
"-
III
>- Base
10
...J
Ycllo~ Magenta Cyan Blue Green Red 81
ack hlhi le
Rough representation of color
transparency or opaque or J9 i na 1 ) .
11
--
material
structure
(negative,

It should be mentioned that durIng the development process taking
place in color negatives, the co10r couplers do not only form yellow,
magenta and cyan. A masking co10r ~ll1 also be formed to prevent
secondary absorptions from taking too much effect on the print. This
way It is possible to obtain better co10r separation. This is why
calor negative films have an orange co10ring, for this is not the
residual fIlter layer of the unexposed film, but the new color having
been introduced for the subsequent processing. Depending upon film ty-
pe and layer deficiencies to be corrected, these masks will be denser
or less dense and will have varying degrees of yellow or red co10r
contents.
Calor negative papers are sensitized somewhat differently. Even though
blue and green will be superimposed also in this case, there is a gap
depending upon the paper type, between green and red. This is the gap
In the spectral range that matches the darkroom safe1ight's co10r. If
there weren't such a gap in the color sensItivity range, color
negative enlarging paper would have to be handled in utter darkness.
Color paper does not have, as already mentioned, the same degree of
sensitivIty In the three layers. The currently available color
enlarging paper responds best to blue light, but hardly at all to red
lIght. This means that the printing light's blue and red contents are
to be appropriately reduced against the light's red color contents.
The color negative film's orange ffidsk does already achieve this
effect, but only partIally so, as It :s not strong enough. This means
that additional filters must be placed in the 1 ight path during
exposures and since red is created by the JOInt effect of yellow and
magenta, it follows that all color negative prInting papers require
the use of yellow and magenta filters. The cyan fIlter remains at zero
as It reflects the light's red color contents.
The printing light's coloring, which consists
color and the enlarger's fIlters, ~Ill thus
paper's sensitivity slope.
of the film's maskIng
compensate the color
--
The six-part color star
The primary colors required for color photography can be summarized on
the color star. The six-part color star shows, in alternating order,
the three subtractive (yellow, magenta, cyan) and the three addItive
(blue, green, red) primary colors.
WIth the aid of the color star we can for example see that yellow and
magenta yield red and that cyan is ccmposed by green and blue.
12

Using the color star it is quite easy to memorize the different mixing
methods.
Red
Magenta
Blue
Cyan
Ye 11 ow
Green
Even more intermediate colors than shown on the six-part color star
are obtained by combining filters of different color intensity.
Example:
A lQc9~ yellow color content and a ~mQll magenta color content yield
orange.
Function and method of operation of the automatic subtractive exposure
system
On conventional subractive color heads (e.g. Durst CLS 501 or CLS
2000) the printing light's color contents in blue. green and red
(coloring) required for obtaining a perfect print in accordance wIth
negative subject, film masking and the color papers sensItIvIty slope,
are achieved by having two each subtractive color filters (yellow,
magenta, cyan) sWing into the lIght path in varYing degrees. In this
case one deals wIth a ~~hi[Q~ii~~ ~~~Q~~[~ ~~~i~m~
However, in the case of an Q~iQmQii~ ~~hi[Q~ii~~ ~~~Q~~[~ 2~2i~mL the
printing light's appropriate color contents in blue, green and red are
obtained by time control. After triggerIng the exposure sequence, the
exposure will be started with so-called white 1 ight, i.e. there are no
printing filters in the light path. As soon as the requIred color
contents In blue, green or red have been obtained the appropriate
prlntlng filter (yellow, magenta, cyan) swings automatically and fully
into the 1 ight path (4) and reflects the corresponding color content.
The exposure with this color is thus finished.
The three printing filters will swing into the light path, either
sequentially or simultaneously, depending upon the length of the
required exposure time (5), (6). Once the third filter (yellow,
magenta or cyan) swings into the light path, the exposure sequence IS
finally over. On the Durst AC 1200, the printing filter's sequential
sWInging-In phase is controlled automatically.
13
-

By havlng swing In all three printing filters (yellow, magenta, Cyan),
the entire white light spectrum will be reflected, which achieves thus
the function of a shutter (6),
Schematic rundown of an exposure
IaoentaFilterI
:yanFiller
Paper
Description of basic filtration function (52)
52
14

Color papers do not have, as already mentioned, the same degree of
sensitivity in all three layers. The currently available color
negative paper for example responds best to blue light and hardly at
all to red 1 ight. This is why in our example the white 1 ight phase (3)
is interrupted after a short time by the swinging-in of the yellow
filter (4) and continued with a green/red exposure. The red exposure
takes the longest time and ends the exposure, i. e. one obtains sub-
stantially differing exposure times for blue, green and red. The white
lIght phase is determined by the shortest exposure time of a color and
the entire exposure sequence by the longest exposure time of a col or.
16
seconds
1.5"
2"
1.5"
8"
blue exposure (yellow filter)
green exposure (magenta filter)
red exposure (~yan filter~
white 1 ight phase
entire exposure time
Exposures of different lengths In blue, green and red (sequential
sWInging-In of the three printing filters yellow, magenta. cyan) do
not prejudice the successful performance of the Ourst AC 1200 system.
Equally long exposures in blue, green and red (simultaneous swinging-
in of the three printing filters yellow, magenta and cyan) however
offer the following advantages when printing well-balanced negatives
or transparencies:
Achieving shortest possible exposure times
Each automatic exposure system has a shortest possible exposure per
color filter;in the case of the Ourst AC 1200 this time amounts to O.S
seconds. Due to the color paper's hIgher sensitivity to blue and green
exposures are going to be shorter than the red exposure, as shown in
our example.
If upon printing the light intensity IS adjusted (via lens aperture or
magnification factor adjustments) in such away as to obtain for
example a blue exposure of one second, the long red exposure Will
nevertheless cause a long exposure cycle. By subtracting red and green
color contents from the printing light, the blue and green exposure
can be lengthened ~rtificially and thus matched to the red exposure.
The entire exposure sequence can then be shortened by opening the lens
aperture.
lS

green
}
filter pack
'-- __ -'IC
C:====::J~~} cut ott tilters
Lf __ --'IC
C==::==JM
filter pack
_____ Lamp
r
JY}
cr====::::J
1M
cut olf filters
C=====:JJ C
1 Sec.
Y r--1 - - - - - - - - -~
8 Sec
M-----"
2 Sec.
M/I- _-----tl- - -- - - -i
8 Sec.
~f-----------11 8 Sec.
CI~----
by opening the lens aperture
8 Sec.
y t-1- - - - - - - - - - -1 Sec.
Mr----i-- ---- - -- _. i1 Sec.
c ~ -- - - - -- - - -i 1 Sec.
16

The printIng 1 ight co10ring having the effect of exposing the co10r
printing paper's three layers (yellow, magenta, cyan) to the same de-
gree is called basic filtration whose values are entered on the baSIC
filtration filters.
When all three printing filters n, M, C) pull in together, i. e.
when the three filter printing tImes are the same, the term "Dead
Heat" is used.
Well-balanced negatives or transparencies may take advantage of the
entire exposure time range ( 1 - 128 seconds).
Schematic representation of the automatic subtractive Durst AC 1200
exposure system in connection with the basic filtration filters
The followIng points should be noted for a better understanding of the
syst em:
-The conventional color paper's three layers do not have the same
degree of sensitivity. The currently avaIlable co1or negative paper
for example responds best to blue lIght and hardly at all to red
1i ght.
- During printing the color negative film's orange mask. which has
been formed during fIlm processing, will absorb green light
corresponding to a density value of approx. D 0.40 and blue light
corresponding to approx. D. 0.60 to partially match the prIntIng
lIght to the color paper's sensitivity slope (In blue, green. red).
-When prJnting,
asafilter.
both negative and transparency are to be Considered
1) Exposure seQuen~e when printing a correctly ba1canced
density) negative on conventional co10r negative paper
17
(co 1 or an d