How Scopes Work — Understanding Lenses and Light Paths
The Swarovski Optik website features a blog with interesting technical articles. In the “On Target” series of blog stories, Swarovski has provided a handy explanation of how optics systems work, with exploded diagrams of rifle scopes, spotting scopes, and binoculars. CLICK HERE for Swarovski Optics Blog.
Scope Terminology
Focusing Lens
The focusing lens is an adjustable lens inside the optical system for focusing the image at different distances…. In the case of rifle scopes, apart from focusing, the focusing lens also facilitates parallax compensation.Diopter Adjustment
For rifle scopes, the reticle can be focused using the diopter adjustment on the eyepiece, thereby correcting any visual impairment. [Editor’s Note: Movable eyepiece diopter adjustment is not offered on all rifle scopes. It is a useful feature on Swarovski and other premium scopes. This allows shooters who need eyeglasses to get a sharply focus image even without wearing corrective lenses. Of course shooters should always wear ANSI-certified eye protection. With the diopter, folks who need correction can use inexpensive, non-Rx safety eyewear instead of expensive prescription safety glasses.]Reversal System
The purpose of the reversal system is to reverse the image by means of prisms in binoculars and telescopes, and lenses in rifle scopes….The lens reversal system is needed in rifle scopes to control the variable magnification and move the exit pupil[.]
Parallax Explained
What is Parallax? What problems can Parallax create when you are shooting? Many novice shooters can’t answer those questions easily. Likewise, many folks don’t understand how to use their front or side-focus parallax controls most effectively. Yes the parallax control basically sharpen focus at different target distances — but there’s more involved. This video offers helpful insights.
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Tags: Lens, Optic, Scope, Swarovski Optik
I have a friendly bone to pick with the editor’s comment about scope diopter adjustemts. Most scopes that I am aware of have adjustable eyepieces. Some have fine, single start threads and lock rings. Because of slow rate of change of this style, the effect of turning the eyepiece does not appear to be the same as is is with eyepieces that have multiple start, fast pitch threads, and which are generally held in place by axial spring tension, without a locking ring….but both systems do the same thing. They allow the group of lenses that make up the eyepiece to be moved as an assembly. They do not change the positions of those lenses relative to each other. The reason that so called diopter adjustments have the plus and minus numbers is that because their adjustment range is all within a single turn, a scale can be used to help locate settings for individual shooter. These plus and minus numbers relate to the position of the eyepiece that would be close to what someone would require who had corresponding corrective lenses. In any case, one can adjust either type of eyepiece so that shooting can be done without corrective lenses as long as their correction is not so extreme as to exceed the adjustment range of the eyepiece. With the fine thread system the process is much more laborious because of the many turns that may be required, and because with that system thread fit is critical, and close fitting threads have more friction. With the fast rate of axial position change that happens with the other system one can get the impression that there is something unique happening, when the same thing is happening, only at a much faster rate. When adjustment is happening at a slower rate, the eye has a chance to try to compensate as the adjustment is made, which changes the perception of what is taking place.
More folks with black rifles shooting at metal targets pretending to be precision rifleman. Seems to follow the theme of the “shooter” who was able to hit a lock at 200yds.
So for clarification, a precision rifle compettetor that runs up a hill with all his equipment including his rifle, climbs a barricade, ranges his target (unknowen) and fires at the target 900 yards away all in under a half minute and makes contact with the steel plate is not a precision rifleman. But a guy that clamps his rifle in a vice and fires at a target 200 yards away is a precision rifleman?
Seems to be a fair amount of guys here that flame the other guys discipline.
EDITOR: Every other guy’s discipline may seem easy … until you actually try it. We have respect for all competitive shooters — from 25m air rifle to Extreme Long Range, and everything in between. FYI, however, even in 200-yard Benchrest competition, the rifles are NOT clamped in a vice. The rigs are supported with front rest/rear bag (LV/HV), but the rifles can definitely still move, as you’ll quickly see when you try. The Rail gun (unlimited) class is different, but again the rig is aimed.
Understand, I was just trying to make a point. I just like to point out that I and many others feel bashing another dicipline is wrong and I am not interested in getting into a pissing contest here.