Handbook of the practice and art of photography (1875)
Vogel, Hermann Wilhelm, 1834-1898, Molling, Edward F · Philadelphia, Benerman & Wilson · leaf 52
neself in buying a new instrument by placing the head inside the camera, excluding all outside light by a cloth, and looking carefully for cracks which might admit the light. To obtain a sharp picture the plate of ground-glass is brought more or less near to the objective. For this purpose the back… … When the part, h, is brought very near to the objective, the pro- jecting board, s, will prevent the operator from bringing his face very closely to the ground-glassysand make perfect focussing rather difficult. * It is more convenient to pull out the front part, r, which moves in grooves inside of…
Photography
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
