Technical Support Document 055 - 7/97

CALIBRATING BLACK-AND-WHITE D-PROBE on the Starlite 55 Colorhead

INTRODUCTION

When printing either color or black-and-white work, it is generally desirable to align your lightsource output to coincide with your lab's standard. Most labs have some form of standard negative, which, in the day-to-day working of the photo lab, will print at a specific Density value at the enlarger.

The Starlite colorhead allows you to change its output light intensity. In color mode, you are also able to easily change the amount of light that goes with a particular density value on the keypad, through the use of the Calibrate Master Color Balance procedure. In Black-and-White mode, this is a bit more tricky, and requires some trickery to make the Starlite lightsource conform to your lab standard.

THE IDEA

This idea takes advantage of the fact that the Starlite's Density probe is designed to change the amount of light coming out of the head that corresponds to the Density value on the main screen. An example of the Density Probe's purpose would be shown in the situation where you just made a print of size 8x10, at a density setting of 64 (for example), and wish to make the same print at 5x7. Once the 8x10 is made, you move the enlarger and focus at the 5x7 size, but the settings at the lightsource would make a print that is too dark. So you use the density probe to show the Starlite the light at the baseboard. The Probe will see the brighter light, and once it is activated, will allow the Starlite to dim the light accurately in order to make a good print at the new size. When this is done, the Starlite is now putting out less light at the same density value!

The above example works the same for both black-and-white and color printing modes in the Starlite. However, the setting of that value of 64 is only directly available in color mode. In black-and-white, we will need to use the Density Probe's ability to change the amount of light that goes with the keypad density number, to make the density number agree with your photo lab's standard.

THE PROCEDURE

The alignment procedure that follows depends on a few settings in the Starlite Preferences Menu to be at particular values. The settings that are important are:

Name of setting in menu: Setting Value:

4: TIME TO DENSITY CORRECTION ACTIVE (This is the default from factory)

9: PROBE WITH AUTOCORRECTION ACTIVE (This is the default from factory)

10: LAMP POWER DISPLAY ACTIVE

For information on how to change these settings, please refer to the Starlite User's Manual. Of course, the Starlite should also be in Black-and-White Printing Mode.

To align the Starlite to your lab standard you will need the following:

Your normal reference ("Shirley") negative for black-and-white. The Density Value at which you want the Starlite to make a perfect print from this negative.

The procedure is as follows:

1. Compose and focus your enlarger to make the standard print. (An 8 x 10 print works well in most cases.)
   
2. Remove the negative from the carrier.
   
3. Select a suitable grade for the standard negative.
   
4. Enter the Density Value for the standard negative into the Starlite keypad. Chances are that the Starlite will beep, and the exposure time will change.
   

If the exposure time decreases, you will need more light from the Starlite as a result of this procedure. If the exposure time increases, you need less light than you are getting for your standard Density Value. This is the most common case.

If you need less light, close your lens almost all the way. If you need more light, open it almost all the way.

5. Re-enter the exposure time to the value at which you want to do your printing. This will cause the density value to change, but ignore it.
6. Temporarily calibrate the probe at this light level. To do this, press MENU, then <6> for "STARLITE CALIBRATION," and press ENTER. From Starlite Calibration, press <6> for "CALIBRATE B/W PROBE DENSITY," and press ENTER again. The light will come on and the screen will tell you to remove the negative and take a probe reading. Place the probe directly under the lens, and press it's button, making sure your hand is not blocking the D-Probe's "eye."
   

The Density Probe is now calibrated to this new light level.

7. If you had opened the lens in Step #6, close it now by about 2 full f-stops. If you had closed the lens in Step #6, open it by about 2 full f-stops.
   
8. With the new lens setting, take a D-Probe reading by placing the Probe directly under the lens, and pressing the button. The lamps will come on, then change intensity, then turn off.
   
9. Once the probing is finished, again enter your desired target density value.
   

If the exposure time changes, repeat this procedure, starting at Step #5.

If the exposure time does not change, the head is now capable of being set to your standard Density Value. The next thing to do is to make a good print at this density value.

10. At the current settings, place a piece of photo paper, and make a print in the normal manner. Most likely, this print will be off in density, and maybe even in contrast grade. Correct the grade by changing the keypad Grade Value. Correct the Density of the print with only the lens aperture. DO NOT CHANGE THE DENSITY VALUE OR EXPOSURE TIME ON THE KEYPAD AT THIS TIME. Do not worry: after this procedure is complete, you will be able to print at whatever lens settings you wish.
    

11. Once the print looks good, we can re-calibrate the Density Probe once more to lock in the final setting. Calibrate the Probe as done in Step #8. This will let the Probe know that the current light level is what the Starlite should have on the baseboard at the current Density setting.

After doing this procedure, you can print at whatever lens aperture you wish, all you have to do is to make sure you Probe after changing it!

If you have questions or problems with this procedure, please contact ZBE at the email, address or phone numbers below.