3.7.4 Eyepiece focus. - The eyepiece focus shall be fixed between
the limits of -0.75 and -1.0 diopter.
3.7.5 Parallax.- Parallax in the center of the field shall not exceed
0.1 mil when viewing a target at 80 meters ± 1.0 meter.
3.7.6 Resolution.- Resolution on the optical axis shall be 10.0
seconds of arc or less when using an auxiliary telescope of at least 3
power having an entrance pupil of at least 0.4 inch. Resolution shall
consist of detectable line structure and proper line count in all four
meridians.Variation in focus between meridians shall not exceed 0.25
diopters as measured at the telescope eyepiece.
3.7.7 Reticle.- The angle formed by the graduations at the outer
extremity of-title shall be within 0.25 mil of the value indicated
on the reticle drawing.
3.8.1 Elevation mechanism.
18.104.22.168 Excursion range.- Rotation of the elevation knob shall cause
the line of sight to elevate and depress a minimum of 300 mils from the
position specified in 3.6(d).
22.214.171.124 Plumb travel.- With the line of sight in coincidence with a
vertical target Zinc, the line of sight shall track the target within 0.5
mil when elevated 300 mils, depressed to 300 mils, then elevated to zero
3.8.2 Azimuth mechanism.
126.96.36.199 Azimuth error.- Error at azimuth readings, taken in 800 mil
increments through two full revolutions shall not exceed 1.0 mil excluding
188.8.131.52 Deflection error.- Rotating the gunner's aid knob to indicate
15 mils followed by rotation of the azimuth knob in the opposite direction
(with backlash removed) to deflect the line of sight 15 mils shall cause
the reset counter to return to within 0.3 mil of the original setting.
This requirement shall be met with the 15 mil value set into each scale
and the azimuth counter indicating 3200, 4800, zero, and 1600 mils at
the start of each reading.
184.108.40.206 Backlash.- Backlash in the azimuth mechanism shall not exceed
1.0 mil when read on the azimuth counter; 1.5 mils when read on the reset