CONTRAST CONTROL FOR 
ILFORD MULTIGRADE VARIABLE CONTRAST PAPERS 
Contrast control with ILFORD MULTIGRADE papers can be achieved in several ways. These include the MULTIGRADE hand filters and the MULTIGRADE 100 or 500 equipment. Contrast can also be controlled with other variable contrast enlarger heads and with colour enlargers. 

CONTRAST RANGE 
This section describes how MULTIGRADE papers give different contrast levels. For practical information on selecting contrast levels turn to the next pages. 
All chloro-bromide (black and white) emulsions are blue sensitive with a slight sensitivity to green light. To make an emulsion sensitive to colours in addition to blue, sensitising dyes need to be added. 
MULTIGRADE papers are coated with an emulsion which is a mixture of three separate emulsions: a basic blue sensitive emulsion and two other emulsions to which are added different amounts of green sensitising dye. Thus, part of the mixed emulsion is sensitive mainly to blue light, part to blue with some sensitivity to green light and part to both blue and green light. 
All parts of the emulsion have the same contrast. They also all have the same speed to blue light, but naturally, the undyed part of the emulsion has a low speed (that is, is less sensitive) to green light. When the paper is exposed to blue light, all parts of the emulsion react and contribute equally to the final image. This image is of high contrast because of the additive effect produced by three emulsions with the same speed and contrast. 
When the paper is exposed to green light, only the dyed parts of the emulsion react initially. This is because the three emulsions have very different sensitivities to green light. The resultant curve has a very much wider exposure range and is thus of low contrast. 
By varying the proportion of blue to green light, a contrast range between these two extremes con be obtained. The simplest way of controlling the colour of the light reaching the emulsion during exposure is by the use of filters: a magenta filter absorbs green light and transmits blue; a yellow filter absorbs blue light and transmits green. In this way, high and low contrast images can be made. 
 

Exposure to blue light     Relative log exposure  A combined curve  B undyed emulsion  C dyed emulsion I  D dyed emulsion II

Exposure to green light     Relative log exposure  A combined curve  B undyed emulsion  C dyed emulsion I  D dyed emulsion II

MULTIGRADE FILTERS 
The twelve MULTIGRADE filters are numbered 00-5 in '/2 steps, with the lowest filter number corresponding to the sofrest contrast. 
Filters are available in sets of filters 8,9x8,9cm (31/2x31/2 inches) and 15,2x15,2cm (6x6 inches). They can be used above or below the lens and can be cut to fit the enlarger filter drawer. Filter sizes 30x30cm are available to special order. 
A filter kit is available for below the lens use. The kit comprises 1 2 mounted contrast filters, a mounted safelight filter and a filter holder. MULTIGRADE filters are very easy to use: no complicated calculations are needed when changing from one filter to another. The exposure time for filters 00-3'/2 is the same; that for filters 4-5 is double. 

MULTIGRADE 100 EQUIPMENT 
The MULTIGRADE 100 system is a very convenient means of exposing MULTIGRADE papers over a wide contrast range. Filtration is continuously variable over the contrast range and is adjusted manually by the grade control. All grades have matched exposure times for convenience. 
The MULTIGRADE 1 00 system comprises the MULTIGRADE 100H enlarger head, MULTIGRADE 100A adaptor kit and MULTIGRADE 1 OOS power supply. The enlarger head replaces the enlarger head on many professional condenser enlargers. It fits into place with the aid of an adaptor kit which is specially designed for each enlarger. The MULTIGRADE 100H enlarger head covers the same negative formats as the original enlarger head, up to a recommended maximum of 4x5 inches. Adaptor kits for the following enlargers are currently available, but new kits are added from time to time. 
 

• Agfa 60
• Beseler 23C
• Beseler 45
• De Vere 203
• De Vere 504
• Durst M605/Mod 70 B&W
• Durst M805
• Durst L900 (Bimacap)
• Fujimoto 90M-0
• Fujimoto 450M
• Leitz IC and IIC
• Meopta Opemus 6/Axomat 5
• Omega D series

MULTIGRADE 500 EQUIPMENT The MULTIGRADE 500 enlarger head and exposure control system replaces the standard lamphouse on most professional enlargers. It fits into place with the aid of an adaptor kit which is specially designed for each enlarger. It is available with either a control unit or an automatic exposing frame. 
There are essentially two MULTIGRADE 500 equipment systems, depending on the size of the enlarger - the MULTIGRADE 500 and the MULTIGRADE 500LE. These are detailed in the tables below. 

MULTIGRADE 500 
 

	MULTIGRADE 500  Small to medium format enlargers  (up to 4x5 inches)
Enlarger head  Power supply  Control unit or  Exposing frame	MULTIGRADE 500H or  MULTIGRADE 5OOHLZ*  MULTIGRADE 500S  MULTIGRADE 5OOCPM or  MULTIGRADE 500E
Optional equipment  Exposure probe  Footswitch	MULTIGRADE 500P**  MULTIGRADE 500F

* The MULTIGRADE 5OOHLZ enlarger head is for some small format enlargers, for example, the Leitz IC and the (FF Auregon. 
* * Only for the control unit. It is not needed with the exposing frame. 
 
 MULTIGRADE 500LE 

	MULTIGRADE 500LE  Large format enlargers  (up to 10x10 inches)
Enlarger head  Power supply  Control unit or  Exposing frame	MULTIGRADE 5OOHLE  MULTIGRADE 5OOSLE  MULTIGRADE 5OOCPM* or  MULTIGRADE 500E
Optional equipment  Exposure probe  Footswitch	MULTIGRADE 500P* *  MULTIGRADE 500F

* This is a special version for the MULTIGRADE 500LE system. 
** Only for the control unit. It is not needed with the exposing frame. 
 
The MULTIGRADE 500 system is suitable for most professional enlargers, including ones from Agfa, Beseler, De Vere, Durst, Fuji, (FF, Leitz, LPL and Omega. New adaptor kits are added from time to time. For more details see the ILFORD technical information leaflet on ILFORD MULTIGRADE 500 equipment. 

OTHER VARlABLE CONTRAST ENLARGER HEADS 
Some manufacturers make variable contrast heads for their enlargers which are specially designed for use with MULTIGRADE papers. Enlarger heads that have been designed in conjunction with ILFORD include those from De Vere, Dunco, Kaiser, Leitz, LPL and Meopta. Follow the instructions provided by the enlarger manufacturer. 

USE 0F COLOUR HEADS 
By adjusting the yellow and magenta filtration on colour heads, it is possible to obtain a wide contrast range with MULTIGRADE papers. However, the maximum contrast will be slightly lower as the filters used in colour heads are optimised for use with colour paper and not with variable contrast paper. 
From the table below, select the type of filtration needed according to the enlarger type. The majority of enlarger manufacturers use Durst or Kodak filtration values. Meopta and Leitz V35 enlargers are mentioned separately in the single colour filter settings table. 

Filtration types used in colour enlargers 

Durst	Kodak
Dunco  Durst  Kaiser  Kienzle  Leitz  Lupo	Advena  Beseler  Chromega  De Vere  Fujimoto  IFF  Jobo  LPL  Omega  Paterson  Simmard  Vivitar

 
Single colour filter settings 
From the table below, read off the approximate filtration needed for each contrast step. However, as the yellow and magenta filters have not been arranged to equalise exposures, new exposure times will have to be recalculated when the contrast is changed. While these figures are a useful guide, the actual filtration needed for a particular enlarger can only be determined by trial. If you are using a Durst enlarger, or one that uses Durst filtration values, choose the suggested settings depending on whether the maximum magenta setting on your enlarger is 170M or 130M.   
  
 

MULTIGRADE  filter	Durst  (max  170M)	Durst  (max  130M)	Kodak	Meopta
00  0  1/2  1  11/2  2  21/2  3  31/2  4  41/2  5	150Y  90Y  70Y  55Y  30Y  0  20M  45M  65M  100M  140M  170M*	120Y  70Y  50Y  40Y  25Y  0  lOM  30M  50M  75M  120M  130M	199Y  90Y  70Y  50Y  30Y  0  5M  25M  50M  80M  140M  199M	150Y  90Y  70Y  55Y  30Y  0  20M  40M  65M  85M  200M  -

* Some enlargers in this group have a maximum magenta setting higher or lower than 170M. For these enlargers, set the highest possible magenta value as an approximate equivalent to filter 5. 
     
EXPOSING LIGHT SOURCES 
MULTIGRADE papers are designed for use with most enlargers and printers, tkat is, those fitted with either a tungsten or tungsten halogen light source. They are also suitable for use with cold cathode (cold light) (ight sources designed for variable contrast papers. 
Other cold cathode (cold light) and pulsed xenon light sources may give a reduced contrast range. The MULTIGRADE 00 filter is particularly useful with these light sources as it significantly extends the contrast range available. Alternatively, some additional yellow filtration, up to 70Y, may help. The contrast range will depend on the spectral characteristics of the light source used. The only way to determine the contrast range available with each model of enlarger is to carry out a practical test.    
  
DIFFUSER v CONDENSER ENLARGERS 
MULTIGRADE papers are designed for use with both diffuser and condenser enlargers. However, because of the different types of illumination there can be a contrast difference between the two types. In practical terms with most negatives, condenser enlargers give about an extra grade of contrast compored to a diffuser enlarger. This contrast difference, though, depends on the amount of silver left in the negative. Thus there is little change of contrast between the enlarger types for very pale, flat negatives and also for the dye image of ILFORD XP2 negatives.