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Microfilm services

Microfilm options

Microfilming: Preservation microfilm options

All microfilm created by OCLC Preservation Service Centers, including high contrast silver-halide film, continuous tone film, and silver dye bleach color film is produced on a non-perforated polyester film base with a silver-gelatin emulsion.

When properly processed and stored, preservation microfilm has a life expectancy of 500 years. We follow ANSI, AIIM and ISO standards and RLG Guidelines for the creation of preservation microfilm, and our stringent quality control measures ensure high technical quality and bibliographic integrity.

We use Herrmann & Kraemer cameras (H&K) for 35mm preservation products. These computer-controlled units offer nearly 40 percent better resolution than Kodak MRDs without sacrificing throughput speed. The H&K cameras provide resolutions from 150 to 200+ line pairs per millimeter depending on the reduction ratios selected. This is the equivalent of 3,800 dots per inch (DPI) to 5,000 DPI. Our H&K cameras are equipped with ExpoSure™, our patented exposure-setting system which produces a narrow density range within a reel of film regardless of the color or fade condition of the materials filmed on that reel.

We also employ reflectance densitometers in conjunction with the camera's computer, which allow nearly automatic exposure over a range of colors and fades. Density variations of .07 density points or less over an entire reel of film are quite common when filming library and archival materials on a H&K camera using ExpoSure™.

Preservation microfilm options include:

  • High contrast microfilm
    We use Kodak Imagelink HQ film for high contrast (black-and-white) microfilming. Our patented ExpoSure™ exposure system allows our staff to pay particular attention to achieving densities that are both appropriate to the material (e.g. low contrast, medium contrast, or high contrast) and consistent within the reel which facilitates legibility and ease of duplication. High contrast microfilm is available in both 35mm and 105mm (microfiche) formats.
  • Continuous tone microfilm
    We developed the Continuous Tone Filming (CTF) process to meet the preservation challenges of creating cost-effective, high-quality reproductions of grayscale materials. CTF reproduces 15 to 16 steps on a 20-step grayscale while achieving excellent resolution. Cameras with high-quality lenses and focusing mechanisms, such as our Herrmann & Kraemer (H&K) cameras, can achieve a resolution of 192 lines per millimeter at a reduction ratio of 12:1. CTF microfilm is available in 35mm and 105mm formats.
  • Color microfilm
    We preserve critical color documents such as maps, patents, postcard collections, drawings, and scientific illustrations using Ilford's Ilfochrome color microfilm, a direct positive silver dye bleach film on a polyester base. Among the most stable of color films, Ilfochrome achieves faithful color reproduction with good resolution (132 lines per mm at 12x) and has an estimated life expectancy of around 300 years in dark storage without appreciable color shifting. It is available in both 35mm and 105mm (fiche).