Standard Printing Time Test Step

To determine the minimum time it takes to achieve the maximum black, perform the standard printing time (SPT) test as follows:

1. Using one of your test exposures, focus your enlarger at the printing size that is normal for your work.

2. Place the blank sheet of film in the negative carrier so the unexposed film covers one-half of the opening. To do this with roll film, you must cut the blank frame in half. Your negative carrier should look like this:

3. Put the negative carrier in the enlarger and make a series of test exposures on a full sheet of normal paper at two-second intervals. Use an f/stop that is in the

FIGURE 67 Negative carrier with film base.

middle of your enlarger's range and try to get as many exposures on the test sheet as possible.

4. Develop the print for two to three minutes in your normal print developer. When this print is processed and dried it should look like Figure 68.

FILM BASE SIDE

PURE LIGHT SIDE

2 seconds

4 seconds

6 seconds

8 seconds

FIGURE 68 Test print.

If the division between the two halves of this print doesn't disappear somewhere along the sheet, you haven't reached the paper's maximum black exposure time. Open up one stop and make another set of exposures.

Note: You may notice a very faint line between the two halves of this print. Just ignore this.

It is important that your test print be dry before you go on to the next step. Most printing papers darken as they dry, and this will affect your judgment of which step is truly black.

5. Count the exposures on the film-base side of the print until you can no longer see the difference between one step and another. The first completely black step on the film-base side of the test print represents the exposure time you are looking for. If this step equals eight seconds' worth of exposure, your standard printing time is eight seconds at whatever f/stop the lens is set. Note this exposure for future use.

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