A compact, portable, visual, telescopic colorimeter has been designed for use in studies of photographic color reproduction. Telescopic viewing permits measurement of the color and luminance of areas as small as ⅜ in. square. Alternative Maxwellian viewing is provided for measuring nonuniform samples or samples having a rough or grainy texture. The precision and accuracy of this instrument have been found to be highly satisfactory.
O. E. MILLER and A. J. SANT, "Portable Telescopic Visual Colorimeter," J. Opt. Soc. Am. 48, 474-477 (1958)