The next step of this test is judging your test prints. Before you begin, it is important for you to know that it's very easy to choose an SPT that is slightly too long. This can be due to your timer being inaccurate or to the fact that printing papers don't always respond logically to accumulating amounts of light. Five two-second exposures might not produce the same effect as one ten-second exposure. Choosing an SPT that is too long will cause you to choose an ASA that is too low. When you get to the point of selecting one print over another, keep this factor in mind. When in doubt, always try a slightly shorter SPT to print your key negative.

You can ignore the test prints that are obviously too light or dark, but two or perhaps three prints should have well-exposed shadow values. At this point, the shadow areas are the only parts of the print in which you are interested. (The highlights of these prints may be too gray or too white, but for now they are not important.)

Looking only at the darker parts of the image, choose the print that in your opinion has the best detail in the shadow areas. The Zone II areas of the print you select should be dark with a trace of detail. The Zone III areas should have good contrast and be fully detailed. Your sketch (Figure 65) will remind you of where these areas are. With this in mind, you should be able to narrow your choice to two prints. Remember that the goal of this test is to find the highest ASA that will give you the best shadow detail in the Zone II and III areas of your prints. If, for example, you are testing Tri-X and the prints representing ASA 300 and ASA 200 both appear to have good shadows, consider ASA 300 your choice. If the ASA 300 print has shadows that are a little too dark, make another print of this negative at a slightly shorter SPT and see whether it is acceptable.

If the shadows of the ASA 300 print are acceptable but the highlights are much too light, choose the ASA 200 print instead. The reason is that step 13 involves correcting the development time of your key negative. If the ASA 300 negative has good shadow detail but requires a reduction in the highlights, shortening the development time may reduce the shadow densities below a usable limit. If this is the case, the extra density in the shadow areas of the ASA 200 negative will give you a little leeway. Using this line of reasoning, you should be able to select the correct ASA for whatever film you are using. Having done this, you are now interested in only one key frame or one sheet of your test rolls or sets.

Don't be surprised if the print you choose represents an ASA that is lower than the manufacturer recommends. This is very common. On the other hand, if you end up with an ASA that is unrealisti-cally high or low (for example, ASA 150 or 600 for 400TX), you have probably made a mistake. Once again, the first thing to check is the SPT. Another common mistake is choosing an illogical area for Zone III. Consider your previsualization very carefully before you make your exposures. Placing the shadow on the wrong zone will throw off your judgment at this stage of the test.

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