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LlDFELDT
November
An important feature of the new finder is that it can be mounted in place of the ground-glass finder without disturbing the camera proper since it is located on the camera door. The conversion is accomplished by eliminating the objective located between the two viewer prisms and replacing it with a !3/4-inch objective located behind the prism system and on the camera door. The ground glass is replaced by a fixed plano-convex collective lens with a frame and cross line etched on the piano surface. This collective or field lens gives a full and more evenly illuminated field of view. The image and reticle are viewed by a 5-power achromat which serves as the eyepiece which is mounted in a focusing arrangement similar to that used in prism binoculars. In
COLLECTIVE EYEPIECE
LENB
Fig. 3 — Fastax view finder.
the initial adjustment and alignment of the view finder, its objective is accurately focused on the camera-film plane so that there is no parallax between the image in this plane and the image formed by this objective upon the collective-lens reticle. The objective is then locked in place. To insure maximum accuracy, all lenses to be used with a particular camera are checked against this setting. This completes the adjustment of the view finder.
In using the view finder, the photographer focuses the eyepiece on the reticle, puts the desired camera lens on the camera, and then trains the camera on the subject. He then focuses the taking lens by turning the focusing ring until there is no parallax between the image and the cross line on the reticle.
The view-finder image is usually bright enough to permit accurate