QA BULLETINS (click here to return to List)

1. OVERVIEW

Evaluation of the Quality of a PAPER MATRIX is currently only possible by actually running it and then evaluating the numbers read by the online densitometer per FINISys recommendations.
The following procedure allows evaluation of the exposure system without the need to run a PAPER MATRIX (and without making any unnecessary changes). Also, the densitometer in use at the QA office can be used.

2. TROD PROCEDURE

The TROD procedure prints 7 different shades of density from the negative selected. The graduation (buttons) from one print to the next is determined by the number of buttons entered (e.g. TROD 1 changes the density by one button from one print to the next). A button of density equals approximately 0.16d. The use of TROD may be useful to evaluate the performance of the exposure system and the validity of the paper matrix, as the prints should show a change in density but not in color.

2.1. PROCEDURE
Select the paper to be tested (usually the master paper channel) and the film channel used for paper Test (TFP). Select the test negative normally used to run the TEST C paper test (#5 or #6) and enter the TROD n command (where "n" equals the number of button steps to be printed from one print to the next). Start the printer, and 7 prints will be made.

2.2. EVALUATION
After the prints are developed, evaluation can be made visually by judging whether the prints follow the same color (grey, or whatever the aim of the paper test is) or whether a color shift is in evidence (e.g. between light and regular density or between regular and high density).

3. DIAGNOSTIC INFORMATION

If a significant blue to yellow slope is visible between the light and dark prints (instead of the light and dark sequence), the Magenta filter(s) in the filter unit must be suspected. These filters were changed by Gretag when the RA-4 papers were introduced, but replacing them in the machine has not been vigorously pursued at all locations. Also, when ordering a replacement by the old part number, such part may actually still be available. Another reason for such a shift may be that filter units have been swapped between printers (in which case 2 printers would actually be off).

• Smaller changes in color may be due to a poorly adapted paper matrix (TDPM) and might be cured by re-running the TDPM procedures.
• The scanner has little influence in the running of a TROD, as all prints are made of the same negative (which is scanned in a single scan).
• Also insure that the paper slopes are really set at 1.000 when doing a TROD (as program 8.3x or 8.40, should not need Paper Slopes, but also DOES NOT check that they are set to 1.000).

4. EVALUATION WORKSHEET

The following worksheet allows evaluation of the TROD using individualized PAP aim values:

To use this worksheet, first enter the aim values (of the TEST C) into the column of print number four, then calculate the expected densities for prints 1,2,3 by subtracting the respective densities (-.45d/-.30d/-.15d), then calculate expected densities for prints 5, 6 and 7 by adding .15d/.30d/.45d. Thus we have goal values that can now be used to compare a TROD run. Note that the density values given are nominals and may vary a) depending on the aim for the normal and b) generally steps at low density are smaller and at high density larger. To compare between different printers, however, the relationship from one printer to another should be close.

This page last modified: May 08, 1997
copyright FINISys Inc. 1997, author: R. Ganahl