METHOD AND APPARATUS FOR AUTOMATIC RANGING WITH VARIABLE POWER TELESCOPIC GUN SIGHT

• US 3,782,822 A
• Filed: 11/08/1971
• Issued: 01/01/1974
• Est. Priority Date: 11/08/1971
• Status: Expired due to Term

• Current Assignee: Mack L. Spence
• Original Assignee: Mack L. Spence
• Inventors: Spence, Mack L.
• Primary Examiner(s): Schonberg, David
• Assistant Examiner(s): Godwin, Paul K.
• Application Number:
  US05/196,698
• Time in Patent Office: 785 Days
• Field of Search: 356/20,21 350/10 33/246
• US Class Current: 356/21
• CPC Class Codes: G02B 23/145 Zoom viewfinders

Abstract

In a variable power telescope gun sight, provided with stadia and aim point at the rear focus between the ocular lens and zoom system, an aim point is located above the optic center and correlated with bullet trajectory. The distance of off set of the aim point is such that, at minimum power, the aim point is zeroed relative to the stadia for impact at minimum range, this usually being the point blank range of the projectile, and at some higher power relative to an increase in range the projectile is again zeroed, in that the projectile impact and the aim point coincide. The novel telescopic sight and method of its use are based on the observations that (1) between approximately 1/3 and 2/3 maximum range and maximum range the trajectory of a high velocity bullet is substantially linear, (2) that as magnification is increased the aim point will appear to move downwardly toward optic center and (3) that the low power and some higher power of the telescope, respectively, can be correlated with a zero at the minimum and maximum range, respectively, with reference to the stadia. Correlated in such manner, changes in magnification, in the optic sense automatically set the aim point for firing without any necessity of the observer knowing the actual distance to the target.

Claims

1. In a variable power telescopic gun sight for mounting on a gun wherein is included the combination of a barrel with enclosed objective lens, ocular lens, zoom system comprised of erectors and magnifiers, which provide a front focus and rear focus, and means mounted on the barrel for changing the magnifying power of the telescope, the improvement comprising locating a reticle, with stadia and a fixed aim point physically located above the optic center of the telescope, at the rear focus between the ocular lens and the zoom system whereby power increases will cause the aim point to appear to move downwardly toward the optic center of the telescope and thereby automatically compensate for the trajectory of a bullet fired from the gun.

2. The apparatus of claim 1 wherein the aim point of the reticle is off-set above the optic center of the telescope by a distance sufficient to correlate a linear bullet trajectory, at high magnifying power, where the gun is zeroed, at maximum compensated range for the gun and, at lower magnifying power, where the gun is also zeroed, with a range defined by the formula ML/MH of maximum;

wherein ML equals the power of the telescope at low power and MH equals the power of the telescope at high power magnification.

3. The apparatus of claim 2 wherein the telescope contains a reticle cell having a vertical cross hair and a pair of parallel horizontal cross hairs, one located above optic center and the other at optic center, the pair of horizontal cross hairs also defining stadia as well as an off-set aim point and a conventional aim point, respectively.

4. The apparatus of claim 1 wherein the stadia are comprised of a pair of lines which adjoin one to the other at an angle of 45*.

5. The apparatus of claim 4 wherein one of the lines is horizontal, and provided with indicia indicative of the height of a target within the field of the telescope.

6. In a variable power telescopic gun sight for mounting on a gun wherein is included the combination of a barrel with objective lens, ocular lens, zoom system comprised of erectors and magnifiers, which provide a front focus and rear focus, a reticle located at the rear focus between the ocular lens and the zoom system, stadia, and means for changing the power of the telescope, a method for correlating the trajectory of a bullet fired from the gun comprising physically locating a fixed aim point within the rear focus above the optic center at a distance such that, at high power, the aim point will be zeroed at the maximum range of impact of the bullet and at low power the aim point will be zeroed at a range defined by the formula ML/MH of maximum range;

wherein ML equals the power of the telescope at low power and MH equals the power of the scope at high power magnification.

7. The method of claim 6 wherein at minimum power the telescope ranges from about one-fourth to about one-half of its maximum power.