Originally Posted by
Nathan Potter
Bernice, your dimensions of 0.000001 to 0.000005 inch for equivalent film resolving power is much too small if you speak of equivalent grain size to dot size. Modern films after development have a typical grain size from 0.5 µm to maybe 10 µm for large clumps. Your figure implies size 0.025 µm to 0.125 µm. (20,000 lp/mm to say 5000 lp/mm). Even the finest emulsions made by Eastman Kodak (Kodak High Resolution Glass Plates) could resolve about 2000 lp/mm. under extraordinarily precise exposure and processing conditions.
By the way I just saw an advertisement by Epson of a new printer with a dot size capability of 25 µm on paper (very smooth paper I assume). Thats 20 lp/mm, 1016 dots/inch. Seems almost overkill for what the human unaided eye can perceive at close viewing distance.
If the print is an enlargement from an original diminutive source then the source film needs to have greater than 20 lp/mm or the information conveyed is emply of the detail that would be possible.
Nate Potter, Austin TX.
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