This view is of the sectioned area of the thick wall of the ocular lens tube of a modern day variable power scope. It shows the position of the reticle immediately inside the ocular lens behind the power adjustment collar. While the reticle does not move from its position in the focal plane, a poorly stabilized erector lens will show grouping changes on target as scope power changes are made.


price range … not just the cheapies. With scopes on a collimator held


totally immobile, I performed a multi- tude of turret adjustments. It became


obvious to observe the causes for a scope not remaining sighted, with the reticle precisely on a grid. As various erector lens adjustments are made, optical col-


linearity is carefully observed. Among the leading defects revealed are slug- gish reticle response where windage or elevation adjustments are made and the reticle fails to repeat or may even be slow in doing so. Imagine a scope being sighted-in only to have it fail after sit- ting awhile in normal storage, or being subjected to recoil. This problem can stem from a weak erector tube return spring, or a lack of precision where the adjusting turret thrust screw makes contact with the erector tube. Some of these scopes tested even had a lubri- cant, which congealed and interfered with precision. Then, as the windage and elevation adjustments were made to extremes, the turret thrust screws arrive below the erector tube radius, thereby causing the reticle to deviate from radial center. This is a cause for op- posing reticle movement as adjustments are made, i.e., the windage adjustment also moves as the elevation turret is ad- justed and vice versa. Holland’s Perfect Picatinny Rail would be helpful in this area, providing lateral rail adjustment, leaving the reticle at optical center. But users of the Picatinny scope mounting


otistec.com Page 68 Winter 2012


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