DARKROOM LIGHT METER DURST VARIOLUX
Is a very compact tool, easy to use. Use a 9 volt alkaline battery and work with any kind of enlarger. Allow both spot metering (from 0,20 to 19 lux) and integral metering (from 0,023 to 2,66 lux). Also, achieve the control contrast and correct paper gradation. The range of sensitivity extends to 6,5 stop. Before printing, you must calibrate the meter for the kind of the preferred papers: However, the procedure is very simple. The paper grade and the exposure are given by LEDs.
• SPOT METERING:
Place the sensor over an highlight zone still showing some details. Then, adjust the lens aperture until the two arrow-shaped LEDs, visible on top of the grade contrast scale, are lit.
• INTEGRAL METERING:
In this case, place the sensor in the centre of the beam created by enlarger head (non matter if a condenser or diffused light), taking care to interpose a diffuser filter in front of the lens. Then, adjust the lens aperture until the two arrow-shaped LEDs, visible on top of the grade contrast scale, are lit. Using the integral metering, avoid searching the highlight still showing some details. The integral metering, however, work better with small enlargements.
• GRADE CONTRAST METERING:
The contrast grade is indicated by the lighting of an LED. To achieve this measurement, you must place the sensor over the shadow zone still showing some details. This mode of operation work both with the spot and integral measurements.
• HOW WORK THE VARIOLUX:
The Durst Variolux work with the exposure time priority. The exposure change by opening or closing the lens aperture, while the exposure time is fixed (considering equal size of prints).
• VARIOLUX DESCRIPTION:
Top left is the sensor (SBC cell), that work both in spot or integral measurement. Just below the sensor cell, are two triangular indicators, corresponding to the two LEDs that indicate the correct exposure when they are switched on simultaneously. Always in the top left, is the selector switch to set the spot or integral measurements. A little below, is the dial that setting the sensitivity meter. On the right side of the meter is the ON/OFF switch.
• CALIBRATING THE DURST VARIOLUX:
Put a negative that show a full grey tonal range, in your enlarger. This negative, also, must have been properly exposed and developed. Determines the print size, properly focus the image and close the lens aperture on average value (f/5.6 or f/8). Set the meter in spot measurement, moving the appropriate switch at the smaller circular symbol. Turn on the meter, with ON/OFF. If the battery is charged and the polarity is correct, the LEDs are lit. Now, place the sensor cell over an highlight zone, that still showing some details. Turning the dial round sensitivities, until the LEDs turn them next to the figure 5. When the LEDs are lit, note the number over the dial sensitivities. At end, make a test strip with increasing exposure (for example, 2, 4, 8, 16 seconds) to determinate the correct exposure time. After the develop of the test print, note the correct exposure time.
NOTE: if you are using the VC paper, make the meter calibration using the 2.5 filtration. When you change the filtration, needs no a new calibration, except for extreme filtration values (00 – 0 – 4.5 – 5). The calibration need for every printing size, according to the following groups:
10x15/13x18 cm ; 18x24/20x25/20x30 cm ; 24x30/30x40 cm ; 40x50/50x60 cm.
• MAKE THE PRINT:
Put the negative in the enlarger, set the requested print size and make the focusing. Set the Durst Variolux in spot metering and turn on the meter. Place the sensor cell on the highlight zone that still showing some details. Set the lens aperture, until the LEDs turn them next to the figure 5. Set the exposure time on the timer and make the print.
• HOW DETERMINING THE PAPER GRADE:
The Durst Variolux, also, allow to determine the negative contrast, suggesting the paper or filter grade. This mode work quite precisely only in the presence of negatives showing a very wide tonal range, from very light grey to deepest. With negatives showing a narrow tonal range, the paper or filter grade indicated by the Durst Variolux need a correction factor.
When the negative is in the carrier, make the focusing. Set the dial round of the sensitivities for the value found in the calibration procedure, according to the actual print size.
Set the spot measurement (as usual), then turn on the light meter. If the battery is good and the polarity is correct, the LEDs light up. Place the sensor cell on the highlights zone that still showing some details. Opening or closing the lens aperture, you must turn on both the LEDs positioned next the figure 5.
When the highlights reading is stabilized, the place the sensor cell over a shadow zone, that still showing details and take another reading.
The paper or filter grade will be displayed by the LED will light up, indicating the “correct” grade figure. If next the “correct” figure grade light up two LEDs, set half grade (for example, 4,5).
Sorry for my bad English language.