Examine dpi of Pictures in Books with Emoscop

<p><font size=+2 color="green">Emoscop is convenient for examine the lines per mm of printed pictures in various books.

<p> I use an EMO-Optik Seibert Emoskop in microscope mode at 25 x to examine the B&W pictures in

several books:

<p><ul><li>Newspaper (Toronto Star) 3 line pair/mm = 150 dpi<li> Joseph D. Cooper: The MINOX MANUAL : 4 lp/mm = 200 dpi

<li> Hubert Heckmann: MINOX Variations in 8x11 : 5 lp/mm = 250 dpi

<li> Alfred Stiegliz in APERTURE MASTERS OF PHOTOGRAPHY : 5 lp/mm = 250 dpi

<li> Andy Warhol Photography: 6 lp/mm = 300 dpi

<li> Lens Work magazine : 7 lp/mm = 350 dpi

<li> Some Canada Post stamps: 8 lp/mm = 400 dpi

<li> Edward Weston Forms of Passion : 12 lp/mm = 600 dpi

</ul><p> In the printed pictures, one lp = one black dot and one white dot = 2 dots.

<p> The basic assceptable resolution is 4 lp/mm.

<p> 5 lp/mm produces good quality pictures..<p> This is a good guide for enlarging negatives based on resolution of lens, ie, 4 lpmm is acceptable, 5 lpmm is good.

</font>

<hr width =20%>

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

at 45 degrees ( X ) manner.