Abstract: A chain saw is movably mounted on a frame for enabling the chain saw blade to move in a substantially straight-line path relative to the frame. The frame includes a bed for supporting a length of wood within the straight-line path of the saw blade. The saw blade is biased toward one side of the length of wood and a foot treadle is connected to the saw for overcoming the bias and moving the saw blade along the straight-line path to the other side of the length of wood.

Abstract: A semi-wide angle objective lens in accordance with the present invention comprises five groups of six lens elements including a front group and a rear group in which the front group has a first group which includes a single positive meniscus lens L.sub.1 with its convex surface directed toward the object side, a second group which includes a single negative meniscus lens L.sub.2 with its convex surface directed toward the object side, and a third group which includes a single positive meniscus lens L.sub.3 with its convex surface directed toward the object side; and in which the rear group has a fourth group which includes both a negative lens L.sub.4 with its front concave surface having a large curvature directed toward the object side and a positive lens L.sub.5 with its rear convex surface having a large curvature directed toward an image side with the fourth group lenses cemented together or arranged with an extremely small air space therebetween, and a fifth group which includes a positive lens L.sub.