Miscellaneous notes about film tests

Film tests should be done for each particular
film development that you desire to use. A sort of standard set of film developments is N+2, N+1, N, N-1, N-2. For each of these film developments, a set of tests should be done. The procedure is as follows:

1. Pick the target exposures and film densities. For instance, for Normal development, the traget exposures are Zone I and Zone 8. The target densities are approximately .1 and 1.25 respectively
   if you are using a condenser-style enlarger.

2. Run a set of tests to determine filmspeed. As a development time, just guess. Try to guess something reasonable, but just guess.
   • Expose not only Zone 1 but also Zone 1/3, Zone 2/3, Zone 1 1/3, Zone 1 2/3. The reason is that any given exposure can be off. We need to know that the Zone 1 exposure is a nearly perfect exposure. Measuring the surrounding densities will confirm that fact. The densities should grow darker at each additional 1/3 stop increment. If two densities the same or if any of the relationships are out of sequence, you cannot be sure that the critical Zone 1 exposure is perfect. Getting the five exposures in proper relationship to each other is the first critical skill. You must dependably be able to meter and expose a film test with *less than* 1/3 stop fluctuation in result. Your results will fluctuate slightly due to uncontrollable factors, but those variations, if you are working carefully, should be no more than 1/6 stop. Several tests may be necessary before you can dependably create a good set of exposures. Even with lots of practice, there will still be occasional mistakes. Testing a range of densities serves to identify the mistakes. It is much much better to make a mistake, identify it and retest than to accept a flawed test as accurate. Below is an example of a great filmtest. Notice that each density is appropriately darker than the preceding density.
     • Zone 1/3 reads .05
     • Zone 2/3 reads .08
     • Zone 1 reads .10
     • Zone 1 1/3 reads .14
     • Zone 1 2/3 reads .17

     Next is an example of a flawed filmtest. It is flawed because two exposures read the same density. This test gives us very little or no trustworthy information.

     • Zone 1/3 reads .05
     • Zone 2/3 reads .10
     • Zone 1 reads .10
     • Zone 1 1/3 reads .14
     • Zone 1 2/3 reads .17

     Next is another flawed filmtest. It is flawed because exposures are not sequential. Likewise this test gives us very little or no trustworthy information.

     • Zone 1/3 reads .07
     • Zone 2/3 reads .05
     • Zone 1 reads .10
     • Zone 1 1/3 reads .14
     • Zone 1 2/3 reads .17

     This test is flawed because the wrong exposure read the desired density. This test gives us extremely useful information. But we will still retest to confirm that information.

     • Zone 1/3 reads .01
     • Zone 2/3 reads .04
     • Zone 1 reads .07
     • Zone 1 1/3 reads .10
     • Zone 1 2/3 reads .14

3. Measure the density for Zone 1. It should be between .09 and .13
   

4. If the density is lower than .09, repeat the test with a lower target
   filmspeed. If you want to know how much lower, guess using the densities
   of the Zone 1 1/3 and Zone 1 2/3 exposures. Say for instance you were testing for a filmspeed of 400. You exposed Zone 1/3, Zone 2/3, Zone 1m Zone 1 1/3, Zone 1 2/3 and got the following densities:
   • Zone 1/3 reads .03
   • Zone 2/3 reads .06
   • Zone 1 reads .08 <-- Zone 1 exposusre for Exposure Index 400, density is too low
   • Zone 1 1/3 reads .11
   • Zone 1 2/3 reads .14

   The Zone 1 1/3 density is right on target. It suggests that our target filmspeed is 1/3 to fast. We will retest at E.I. 320. If the result is consistent, we'll have confirmed that the filmspeed for the amount of development time given is known.

5. After confirming the filmspeed, work on the development time. If you are testing for normal development, Expose Zone 7 1/3, Zone 7 2/3, Zone 8, Zone 8 1/3, Zone 8 2/3. Also, on hte same roll of film, include the filmspeed test you did a minute ago. Your test for Normal development then has several exposures on it.
   • A hand written note (details to follow)
   • A blank frame exposed with lenscap on (used to establish filmbase + fog density
   • Zone 1/3
   • Zone 2/3
   • Zone 1
   • Zone 1 1/3
   • Zone 1 2/3
   • Zone 7 1/3
   • Zone 7 2/3
   • Zone 8
   • Zone 8 1/3
   • Zone 8 2/3

   As you may have already seen, there are advantages to using an alternate order that expedites shooting and measuring the film for these exposures. The alternate order is not necessary; it is advantageous.

6. The densities for the upper zone must fall into appropriate relationship just as they did for Zone 1. In fact, for the test to be trusted, all ten exposures (five for filmspeed and five for a higher -numbered zone) must be in appropriate relationship. Below is an example of such results. This is the goal for a "Normal" film test.
   • Zone 1/3 reads .05
   • Zone 2/3 reads .08
   • Zone 1 reads .10 < -- right on target
   • Zone 1 1/3 reads .14
   • Zone 1 2/3 reads .17
   • Zone 7 1/3 reads 1.09
   • Zone 7 2/3 reads 1.18
   • Zone 8 reads 1.25 < -- right on target
   • Zone 8 1/3 reads 1.30
   • Zone 8 2/3 reads 1.39

7. If the densities do not fall into the pattern suggested, then you must retest for both filmspeed and development until they do. It frequently takes 20 to 30 film tests to get a complete set of results. The reason is that the first several tests invariably can not be repeated. It just takes a while to work all of the inconsistencies out of film development.
   • developer not the same temperature every time
     • using different thermometers
     • inconsistencies in stabilizing the developer temperature
   • variations in agitation
   • variations in developer strength
     • developer mixed at different dilutions
     • stock solution age and/or age of working solution
     • varying amounts of working solution used
     • variation in the number of reels in a tank
   • inconsistent exposures
   • bad metering
   • light changed between metering and exposure
   • inaccurate notes taken!
   • use of different lenses and/or shutters from one film test to another
   • use of shutter speeds that are inaccurate in a harmful way
   • using different cameras or even different film formats
   • a kazillion other miscellaneous inconsistencies that are only discovered
     sometimes but eventually go away on their own.

   It is psychologically grueling. You should undertake the process knowing that everyone who came before you failed to produce reproducible results in early tests. You can recognize that you are on the wrong track when you catch yourself thinking or saying something that could possibly be interpreted as implying that the laws of physics have been repealed on your behalf . When you catch yourself claiming that you did everything consistently but the manufacturers of the film, developer or some piece of hardware make a product that *cannot* yield consistent results, you have arrived at a special moment. You have arrived at the moment where you can take stock and control of everythng you have done and proceed again -- but more carefully. Normally film testers only arrive at this point after they have gone through many tests being perfectly willing to accept that they are the source of inconsistency. Then something often happens causing the human spirit to believe that it has done enough work, that it has achieved the necessary consistencies and *something* else is "the problem".

   I will tell you that on the other side of such understandable attempts to avoid responsibility for the problem are fairly simple lab procedures. After you have it, you probably just have it. It is like the rest of the Zone System, once you get it, it seems quite a bit simpler than it did before you got it. After your lab habits are banged into consistent form, you will use them without thinking about them and without worry that one day 125 kabillion photons yields a zone 1 exposure but the next day yields a different exposure. It really doesn't take as long as it seems like it is taking. First work on exposing the film correctly and consistently; next work on developing it consistently. You'll be fine. It is easier to start by testing for N-1 development and film speed than it is to start by testing for Normal development and film speed. After N-1, test for Normal, then N+1, then N+2. By the time you have all of those, you'll be able to knock out N-2 in a stunningly short series of tests. It will be most gratifying.