gregory t. davis

Film Speed

To begin, you will need to settle on which film and developer combination you want to use. You can test several films, if you like, but using one film consistently with one developer will not only eliminate expense, but give you time to learn the subtleties of your materials. The same goes for paper and paper developers.

Once you have chosen your film, paper, and developers for each, you will need your camera, lens, and a few film holders. Place a card, such as a piece of black matte board or a gray card, against a wall. Make sure there is no texture in the board and it is evenly lit. Don't place it such that your shadow falls on it. I find it easiest to tape the card onto the wall and set my camera on the tripod. Set your focus at infinity and place the camera close enough that the card fills the frame. Bear in mind that the card will not be in focus.

Now we are ready to begin our exposures. Set your meter to the manufacturer's recommended speed and meter the card. Set your shutter to achieve a Zone 1 exposure. This is four stops under-exposed. Adjust your lighting, if necessary, to get a Zone 1 exposure with the shutter at a medium speed and middle aperature. You will need to adjust the aperature in both directions later, so starting in the middle gives you some latitude. Using a medium shutter speed, such as 1/50 of a second will prevent any chance of reciprocity failure or shutter malfunctions.

With your shutter set at the manufacturer's film speed, remove the darkslide half way and expose for Zone 1. Change to another piece of film and adjust your meter to 1/3 stop slower. For example, if you are testing a 100 speed film, sheet one would be exposed for Zone 1 at an ISO of 100. Sheet two will be exposed for Zone 1 at an ISO of 80. To achieve this, you change the film speed on the meter to the new speed and adjust the shutter to make the Zone 1 exposure. This is usually achieved by opening the aperature by 1/3 stop.

Expose only half of the sheet as before and continue adjusting the film speeds until you have exposed for two whole stops below the original setting. IE, if the original speed was 100, expose in 1/3 stops until you get to an ISO of 25 for a total of seven exposures. Then reset your meter to the manufacturer's speed and increase your meter settings in 1/3 stop increments until you have reached two stops faster than the manufacturer's speed. Giving an additional six pieces of film for a total of 13 sheets.

It is now time to develop them and see which is the correct speed for your methods. Develop the film in a single batch using the recommended dilution and time, and include a piece of film that is completely unexposed. The reason for developing all 14 sheets at once is to eliminate the possibility of changes in the developer affecting your results. If 14 sheets of film are too much for you to handle in a single batch, reduce the number you expose by only going one full stop above and below the manufacturer's speed giving you a total of 8 sheets to develop at once.

Before printing your test negatives, expose a piece of paper with your enlarger or printing bulb from your standard height. If you regularly print to 11x14, set your enlarger at that height, or whichever setting is most common for you. Adjust your exposure time to achieve the shortest amount of time to create a full black. It is important that you use the shortest time possible. This is your standard printing time.

After determining this time, contact print each test negative. The result you are looking for is the negative that gives you the first amount of separation from the exposed area and the unexposed area, while printing at your standard printing time. This negative is your new film speed. If the 100 gives you the first separation of blacks, then use 100 for this film, if it was 64, use 64 and so on. There is a good chance that the speeds faster than the manufacturer's will not give you any separation at all, while the the slower speeds will give far too much. Judge carefully which gives you the first noticeable difference.

Development Time

For the first part of this test, we used the recommended development time. Since we were looking for a Zone 1 density, dramatic differences in development time aren't going to affect much. However, when we use the film, these little differences will make big changes in highlight densities. Thus we will need to find our own development times. To do this we will need to set up our card and camera as before. This time, however, we will meter for Zone 9.

Set your meter to the film speed you determined to be best from the first test and expose six sheets to Zone 9, or three stops over-exposed. Make every exposure at the same shutter setting.

Once you have your exposures, develop the sheets, removing one sheet from the developer every minute. Choose a time that is close to the recommended time, for example, if the recommended time is 6 minutes, remove the first sheet at 4 minutes, the second sheet at five, and so on. Once all the sheets have been placed in the stop bath, continue processing as normal.

After these test negatives have dried, set your enlarger or printing light to your standard height as before. Using your standard printing time, expose each negative in turn, covering half of the negative with a card as you do so. This will give you one side through the negative, and one side blank white. Look for the print that shows the first separation of grey from the paper white. This will be your normal development time.

To establish your N+!, N+2, and N- times, expose a series of negatives as such: Meter the card and expose six sheets of film for Zone 8. Develop these in increments like before, removing them one at a time each minute starting at your new normal development time. Print them, covering half, and look for the first negative to show separation from the paper white. This should be the same shade of grey as the Zone 9 negative, giving you your N+1 development time. Repeat, exposing at Zone 7, and determining again which development time prints identical to your Zone 9 using your standard printing time.

N- times are identical in procedure, but expose for Zone 10 and start pulling your negatives sooner than your normal time.

By establishing your personal film speed and development times, you wil get more consisent print exposures and film scanning procedures.