We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
Con
denser pro
i-io"
2-10"
3-10"
4-10
5-10
perlv centered Relative light on Screen (Lumens) 100 up' " " " " " 88.0
" 58.5 29.0
22.5 22.0
A slight change in the distance between the condenser and the aperture plate has little effect, though the distance should be approximately right, /. e.^ 5" for the 3^'' diameter condenser and (i]4" for the 4^" diameter. Tests on the ^^2" diameter condenser showed the following variation in screen lumens obtained by moving the lens ahead of and behind its proper location:
^Condenser 6^" from aperture plate Relative Light on Screen (Lumens) 100
6K"
_ll
7
iW
7K"
6K"
6"
sY^"
sW
103
' ICO
' 100
103
103
' 105
105
97
Presumably the condenser and objective lens are properly lined up at the factory and it should not be necessary to change this setting. It is w^ell, however, to check this matter and to use great care after moving the lamp-housing sideways for lantern slide projection to get it back in the proper position before continuing the motion picture projection. There are three simple methods by which the centering of the condenser may be checked:
Let one man, provided with a piece of dark glass, place his head in the beam of light about 10 feet in front of the projector and look through the dark glass directly into the objective lens. The observer's head should be in such a position that the shadow thereof falls on the exact center of the lighted part of the motion picture screen. Looking into the objective lens through the dark glass, the corrugations on the condenser become clearly visible. An assistant should then move the condenser until these rings are concentric with and centered in the objective lens (Fig. XIL A and B.)
If one is to line up quite a number of machines, time may be saved by having a simple mechanical device made for this purpose (Fig. XIII). The device consists of a straight rod (A) pointed at each end. x^ section of a cone (B) of such a diameter that its center will fit snugly into the objective lens jacket after the lens tube has been removed. This cone-shaped piece also has a hole through it fitting snugly to the rod (A). A tapered rectangular piece (C) is also provided to fit snugly into the aperture plate. This piece also has a hole in it fitting rod (A) snugly. A circular plate (D) is provided with a good substantial shoulder bored to fit rod (A). These parts may be made of steel or wood, preferably steel. In using them remove the lens tube from the objective lens and insert cone (B) in the jacket. Insert rectangular
*The distance between condenser and lamp remaining fixed.
61