"Don Stauffer in Minneapolis" wrote
Nicholas O. Lindan wrote:
Photographic paper can get to 2.0 od reflected, a range of 10 ^ 2 = 100:1.
Unless print paper has changed in the twenty-five years since I made
some of those measurements, paper doesn't quite get to 100:1. I have
seen papers with blacks at 2% (50:1). Most papers have about 3% black
reflectance, however (33:1).

It is a non-specula measurement. 2.0 isn't hard to get to. However,
2.0 is not a good value for making prints with any shadow detail as
it is up on the shoulder. 1.8 OD is a better max value, closer to
2%, as you indicated.

At one time I worked on a project finding black coatings for cameras and
other EO sensors. It is amazing how hard it is to get a truly black
black. Even the famed 3M Black Velvet was a 2% reflectance. The only
thing we found was a coating by Martin Marietta that was close to 1%.

Not only isn't it black, it's yellow, or blue or red ... Black, like
white seems to be an imaginary concept.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
To reply, remove spaces: n o lindan at ix . netcom . com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/