Paragraph
Telescopic sights (ZF.20E or ZF.20) with elevation quadrant for direct fire   .....		74

74. TELESCOPIC SIGHTS (ZF.20E OR ZF.20) WITH ELEVATION QUADRANT FOR DIRECT FIRE.

a. Description of Telescopic Sight (ZF.20E).

(1) The telescopic sight Flak ZF.20E (ZF, Zielfernrohr, meaning telescopic sight) (figs. 79 to 81) is used for direct fire. It includes an elbow telescope, angle of site mechanism, range quadrant and elevation mechanism, and deflection mechanism.

Figure 79 — Telescopic Sight ZF.20E — Front View

(2) ELBOW TELESCOPE. The elbow telescope is of fixed focus type, has 4X magnification and a field of view of 17 degrees 30 minutes. The image remains erect during the rotation of the telescope. The filter knob and detent positions each of the filters: clear, green, light neutral and very dark neutral. A window and a dovetail surface permit attachment of a lamp for illumination of the reticle. The reticle pattern (fig. 81) permits rapid centering of reticle on target in desert glare and has indications for estimating lead.

(3) ANGLE OF SITE MECHANISM. The angle of site mechanism rotates the telescope and deflection mechanism within the main housing. The angle of site scale is graduated in 100-mil intervals from plus to minus 200 mils. Zero is normal. The angle of site micrometer is graduated in 1-mil intervals from 0 to 100 mils. Stop rings limit motion within the limits of the scale.

Figure 80 — Telescopic Sight ZF.20E — Top View

(4) RANGE QUADRANT AND ELEVATION MECHANISM. The range and elevation knob rotates the entire telescope and angle of site mechanism in the housing. On each end of the worm is a drum and pointer. One drum indicates elevation in degrees and is graduated from 0 to 12 degrees in 1/6-degree intervals. The other drum is graduated in 100-meter intervals from 0 to 94 meters.

Figure 81 — Telescopic Sight ZF.20E — Reticle Pattern

(5) DEFLECTION MECHANISM. Deflection may be set into the sight by rotation of the deflection knob. The deflection scale is graduated from 250 mils left to 250 mils right.

(6) A blank eyeshield is provided to rest the observer's eye. The shield may be adjusted for interpupillary distance.

(7) The telescopic sight has two trunnions and a clamp for installation on the telescopic sight bracket of the mount.

b. Description of Telescopic Sight (ZF.20). The telescopic sight (ZF.20) (figs. 82, 83, and 84) is similar to the telescopic sight (ZF.20E) but lacks the range drum. The gun commander must memorize the range equivalent to some of the elevation scale readings.

Figure 82 — Telescopic Sight ZF.20 — Front View with Eyeshields Swung Down and Forward

Figure 83 — Telescopic Sight ZF.20 — View of Bottom from Front

Figure 84 — Telescopic Sight ZF.20 — Side View

c. Elevation Quadrant.

(1) The elevation quadrant (fig. 85) is used in direct fire sight (ZF.20E or ZF.20) for laying the gun in elevation. The elevation quadrant includes a quadrant, an outer pointer, an inner pointer, and a link to the telescopic sight bracket.

Figure 85 — Elevation Quadrant

(2) The quadrant is centered on the cradle trunnion and is fastened to the mount. In operation the quadrant remains stationary. The quadrant is graduated in 0.25-degree intervals from minus 3 degrees in depression to plus 85 degrees in elevation.

(3) The outer pointer (quadrant elevation pointer) is fastened to the cradle trunnion. It bears an index which alines with the quadrant scale, indicating the elevation of the gun.

(4) The inner pointer (direct sight elevation pointer) pivots on the cradle trunnion and moves with the bracket of the telescopic sight. The pointer has an index line which alines with the index of the outer pointer.

(5) The link connects the inner pointer with the bracket of the telescopic sight and has a turnbuckle for alinement of the sight with the gun bore.

(6) When the elevation quadrant, the link, and the telescopic sight are in adjustment, the gun may be laid in elevation by setting the desired elevation or range in on the telescopic sight and matching the pointers on the elevation quadrant.

d. Operation.

(1) INSTALLATION. Examine trunnions and mating surfaces for nicks and burs. Set the trunnions of the telescopic sight in the proper slots of the telescope bracket and clamp the telescopic sight firmly in place.

(2) BORE SIGHTING.

(a) Remove the firing pin and use the firing pin hole as the breech bore sight. Improvise the muzzle bore sight by fastening two pieces of cord or wire across the muzzle face, locating the cord in the horizontal and vertical grooves on the muzzle face and securing with a strap around the barrel close to the muzzle.

(b) Lay the gun on a well defined distant aiming point by sighting through the bore. Turn the handwheel of the telescopic sight bracket (just below the bracket) to match the direct sight elevation pointer with the quadrant elevation pointer. Set the range scale, the angle of site scale, and the deflection scale of the telescopic sight to "0." The telescope sight should now be on the distant aiming point.

(c) If error in elevation exists, lengthen or shorten the link bar by adjustment of the turnbuckle.

(d) Errors in azimuth may be corrected by turning the telescope deflection micrometer until the telescope alines in azimuth with the distant aiming point, then loosening the three screws in the end of the micrometer, slipping the scale to zero, and reclamping.

(3) DIRECT FIRE OPERATION.

(a) The azimuth gun pointer sits behind the telescopic sight with the traversing handwheel at his left.

(b) The angle of site scale and micrometer should be set at zero.

(c) The elevation for range in degrees and 1/16 degrees is set in on the elevation scale or in meters (on ZF.20E only) on the range drum.

(d) The deflection in mils, if large, is set in on the deflection drum. (Red graduations bring the piece to the left.)

(e) Small deflections may be estimated on the reticle (fig. 81).

(f) The gun is laid for elevation by matching both pointers of the elevation quadrant.

(g) The azimuth gun pointer tracks the target with the traversing handwheel.