Characteristics of Ilford DELTA 400 Professional 120:
Ilford DELTA 400 Professional 120 is a professional high-sensitivity black and white panchromatic sensitized negative roll film characterized by high resolution, large dynamic range and rich tonal range. The nominal sensitivity of the film is ISO 400, but its wide exposure flexibility gives very good results even at moderate overexposure (200 ISO) and underexposure (3200 ISO).
Panchromatic films react to reality in a similar way to the human eye, which perceives light rays with wavelengths from approximately 380 nm to 740 nm (visible light), but in some cases can also be sensitive to the UV and IR component of light. It is therefore advisable to have a UV filter on the lens to suppress the effect of radiation on the film material.
In order to achieve the correct sensitivity to the entire spectrum of visible light, this film is sensitized, which guarantees the correct conversion of the colour reality to the grey scale. If the film were not sensitized, it would not be able to respond to light rays of a certain wavelength, and so the resulting photographs would lack some parts of the tonal range. For example, the film would not respond to green, yellow, orange and red, i.e. it would not detect them and on a black and white positive these shades would be black or otherwise dark. Such material finds application mostly only in the field of scientific and industrial photography, where these "deficiencies" are dealt with deliberately.
Practical application:
The use of emulsion technology of layered flat silver halide crystals has made it possible to significantly change the conventional relationship between sensitivity, resolution, grain size and speed of development. This technology has thus enabled the development of Ilford DELTA 400 Professional film, which has comparable properties to ISO 100/21° sensitivity films. At optimum exposure, the film provides a very rich range of halftones and faithful drawing in both highlights and shadows. Thanks to these useful features, it finds its application not only among documentary and sports photographers but also among landscape and portrait photographers.
Film processing:
Safe lighting when developing is either infrared light or complete darkness. Ilford DELTA 400 Professional film can be processed in all common negative developers (but Ilford ID-11 or Kodak D76 are recommended). The developing bath should take 14 min for Ilford ID-11 and 14 min for Kodak D76 at a dilution ratio of 1:1. After the development time has elapsed, it is recommended to rinse the film briefly with distilled water or immerse it in a 2% acetic acid solution for 10 s, or use a break bath for approx. 1 min. Setting of the film is recommended at temperatures of 18-25°C, 2-5 min in Ilford Rapid Fixer diluted 1:4, or a minimum of 3 min in Fomafix Rapid Fixer diluted 1:5. After setting, the film must be washed in running water for 20-30 minutes at a wash water temperature below 15°C, or 15 minutes at a wash water temperature above 15°C. It is recommended to finish the film processing by rinsing the washed film with distilled water or by immersion in a wetting agent solution. When developing and settling in the developer bath, it is advisable to shake the developer during the first minute and every 10 seconds thereafter. For optimal results, it is advisable to maintain the manufacturer's recommended time and speed of shaking, but also the correct bath temperature (20°C), dilution ratio (1 part solution : n parts water) and their quality (freshness, cleanliness).The times given are only indicative, before using the film material we recommend to study the data provided by by the manufacturer on the packaging or in the product data sheet.
