Emoscop is convenient for examine the lines per mm of printed pictures in various books.

I use an EMO-Optik Seibert Emoskop in microscope mode at 25 x to examine the B&W pictures in several books:

• Newspaper (Toronto Star) 3 line pair/mm = 150 dpi
• Joseph D. Cooper: The MINOX MANUAL : 4 lp/mm = 200 dpi
• Hubert Heckmann: MINOX Variations in 8x11 : 5 lp/mm = 250 dpi
• Alfred Stiegliz in APERTURE MASTERS OF PHOTOGRAPHY : 5 lp/mm = 250 dpi
• Andy Warhol Photography: 6 lp/mm = 300 dpi
• Lens Work magazine : 7 lp/mm = 350 dpi
• Some Canada Post stamps: 8 lp/mm = 400 dpi
• Edward Weston Forms of Passion : 12 lp/mm = 600 dpi

In the printed pictures, one lp = one black dot and one white dot = 2 dots.

The basic assceptable resolution is 4 lp/mm.

5 lp/mm produces good quality pictures..

This is a good guide for enlarging negatives based on resolution of lens, ie, 4 lpmm is acceptable, 5 lpmm is good.

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Note: In all the printed pictures I have examined, the grid is not arranged in horizintal/vertical manner( ++) but at 45 degrees ( X ) manner.

-- martin tai (martin.tai@capcanada.com), April 20, 2000