Tech Notes

DOWNLOAD this Article as a Word Document

ENLARGED NEGATIVES: THEORY & PRACTICE

Now that we have the lab in shape for negative making let's take a look at the films with suitable characteristics for the job at hand, starting with making the interpositive. This film should be fine grained, capable of lower than normal contrast, and have a long straight section on its HD curve with minimal toe and shoulder. The correct positive should look like a flat print when viewed on the light box, with no areas of clear film (some density in all non-specular highlights) and no shadow areas near the D-Max of the film. This places all the printable information from your original negative on the straight portion of the film curve insuring good tonal separation. One film with these characteristics is Ilford's Commercial Ortho Plus, a graphic arts film which I have been using successfully for the past five years. Another alternative would be T-max 100 which is not a graphic arts film but has characteristics which make it suitable for many aspects of photography including copying, masking, color separations, and normal picture taking. It is the closest thing available to an all purpose film and may cause the disappearance of a number of other Kodak film stocks. These films are readily available in sizes up to 8X10. Should larger size film be required, The film stock referred to as Fine Grained Positive (not the same as Kodak Fine Grain Positive) supplied by Photo Warehouse is available in sizes up to 20 inches and acts much like the Ilford Commercial Ortho. There are some situations where using a film positive the same size as the final negative is advantageous. If the original negative is smaller than 4X5 inches, generating the positive by contact (to avoid going through two enlargements with attendant loss of quality) to arrive at the final negative will result in grain from the positive influencing quality of the negative due to the degree of enlargement. To make an 8X10 or larger negative from a 35mm original, it is better to make an 8X10 or larger positive and contact to make the negative. An other situation would be if the original negative is larger than 8X10. All the above films respond favorably to processing in Kodak's HC110 or Ilford's Ifotech developers.

And now to the final negative. This is the phase where most of the controls such as contrast adjustment, dodging and burning and retouching are applied. One film ideally suited for this application is Kodak's Professional Copy Film, number 4125. It is specifically designed for generating copy negatives, having a uniquely shaped shoulder on its film curve which enhances highlight separation to counteract the highlight compaction usually occurring when making copies. It is also unique in that contrast is influenced not only by development time but exposure as well, increasing exposure resulting in increased contrast. It is retouchable on both sides, and is available in sizes up to 20X24. The disadvantages are that it is very expensive and supplies, especially in the larger sizes, are limited, as it seems that Kodak only makes this particular film once a year and supplies are exhausted before the next run. This is a great film and is highly recommended but at the time of this writing has been unavailable for two months. While I wholeheartedly recommend this film for enlarged negatives (I have been using it for 15 years) I believe its future as an available product is limited. As digitally produced negatives for reproduction occupy an ever increasing share of the market, the future of specialty films like Pro Copy is uncertain at best. An alternative must be found and camera oriented films promise the best availability. Fortunately some of the new generation films have very gentle shoulders and are adaptable for use in generating enlarged negatives. The aforementioned T-Max 100 would be a good choice but is unavailable in sizes larger than 8X10 except through special order (cost prohibitive). Photo Warehouse markets an ISO 125 Pan film for camera use which is available in sizes up to 20X24 which I have been using lately for enlarged negatives with great success. Selenium toning the final negative mimics the highlight characteristics of the Pro Copy and the film responds favorably to increased development which is necessary to achieve the higher than normal contrast required for most alt process negatives.