Using the KY-NDNP Quick Guide Formulas below,
insert your values then choose the appropriate function


Calculating Line Pairs

Reduction Ratio X Tech Target Chart (ex. 5.0, 6.3) = Line pair

  • 22x X 5.0 = 110mm

Calculating Capture Resolution Film

Reduction Ratio X Capture Resolution Original (ex. 300dpi, 400dpi) = Capture Resolution Film

  • 22x X 300 = 6600dpi

Determining Film Generation

  • Odd generations = Emulsion side in
  • Even generations = Emulsion side out

The emulsion side is identified as the dull side while the base side is shiny. If you still can't tell, it might help to know that the emulsion side is easily scratched. We don't recommend discovery this way but, if you must...

Calculating True DPI

Pixel width / Width of a actual page (in inches) = True DPI

  • 6000 / 18 = 333.33dpi

If no source document exists to take an exact measurement, the title is likely listed in the N.W. Ayers Guide. The other option is only available when there is a target on the film that includes a unit of measurement, such as a ruler. One can calculate the actual size of the paper using that ruler and a handy pair of calipers!

Calculating Exposures per Reel (the Reverse of Reel Programming)

There are several things to consider when calculating exposures per reel; length of microfilm reel (usually 100' or 125'), reduction ratio, and the orientation in 1A, 2A, 1B or 2B formats. Research Libraries Group (RLG), now part of OCLC, offers an excellent calulation table in their Archives Microfilming Manual. Unfortunately, the table does not go up to 20x reduction. On average, we get about 650 exposures of modern newspapers on 100? roll of film. That would be about 1,300 pages in 2B format. Generally, the ratio of 2B to 1A is 8:5. Theoretically, roughly 800 pages will fit on a 1A reel at 20X. In practice, generally 650 to 700 pages of modern newspapers will fit on 100' reel. Which is to say, this formula will produce only a rough estimate.

Reel Length; Reduction Ratio; Orientation (1A, 2A, 1B, 2B) = Estimated Exposures per Reel

  • 1,300 pages@2B@20x / 100' = 13 pages per foot

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