Make careful notes of the exposure for each frame. Now cap the lens and shoot off two or three frames to produce some zone 0 totally unexposed negatives. Use the rest of the roll on any old pictures - we just need to avoid processing with lots of blank frames, which might affect relative developer activity. Obviously sheet film users just shoot the precise number of frames they need, including a zone 0. Now develop in your normal developer. Development time has little effect on low zone areas compared to high, but it does have some, and we are working very close to the lower limit here. So contrary to normal textbook advice to use the developer manufacturer's recommended development time for your film, I ask you to develop for 20% less time for reasons that become very clear later. Use an absolutely standardised development routine for equipment, temperature, agitation, pre-wet, etc. Be meticulous - it makes you feel good! Set up your enlarger at around a medium-sized enlargement and focus accurately using any suitable negative. Replace the focusing negative with a film base plus fog zone 0 frame from the test shots and stop the lens down two or three stops, as convenient for subsequent length of print exposure. Use freshly mixed supplies of your preferred regular processing solutions at precise temperatures, and your normal paper. If graded, use grade 2; if variable contrast, use the exact middle grade of 2.5. Using one second increments, or smaller if you can control them accurately, make a test strip of the zone 0 frame such that there are steps of grey across the print reaching full black about half way across the strip. Develop this in an absolutely standard and repeatable way. I strongly advise you not to standardise on an extended development time. You now need to find the first step on the test strip which reached maximum black, but don't judge this until the print is dry! The first black strip will be the one which can't be distinguished from its neighbour. It's normal for strips that are obviously different when wet to merge when dry - known as the 'dry-down' effect. Once this minimum exposure time for maximum black has been established, you simply substitute each of the theoretically correct and bracketed zone 1 negatives in turn, making no other changes to the enlarger settings or processing procedure. Give each of these negatives exactly the same exposure time as the minimum required to produce maximum black on the zone 0 negative. This is the source of another common error, both in this test and in making print exposures after test strips normally. Having made the test strip in a series of intermittent short exposures, the subsequent print is mistakenly made with one long composite exposure. For example, if the test strip showed correct exposure at seven one-second exposures, the print is then made with one seven-second exposure. Due to what is known as 'the intermittency effect', this is wrong. The single longer exposure will produce significantly greater density than several intermittent ones of the same total duration. Even many professional printers are unaware of this and attribute the difference to dry-down, which is present as well. So make your actual prints exactly as the test strip, in exactly the same multiple intermittent exposures. Mark the original camera exposure on the back of each print as it is made. When they are dry compare them with the maximum black print, and find the print which shows the first change away from black. This is zone 1 for you, and only for this equipment and technique. Theoretically, if you change anything, you should retest. In practice, it's not critical unless you're a fanatical purist. However, it's wise now and then to retest anyway with negatives tagged on to a normal film - materials and techniques gradually change and drift. I have never yet known a film speed that a zone 1 test did not discover to be lower than the maker's rating. The amount of variance will show by how much you had to 'overexpose' marked on the back of the relevant print. For example, if you had to over-expose by one stop to get your zone 1 negative, you need to halve the manufacturer's recommended rating. Unless you shoot with your own true film speed, you will always have empty black shadows unavoidably.