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I don't intend to
do a 101 on rifle scopes, there is plenty of that in any of the gun rags, but
there is one aspect of a telescopic sight I have never read, and thought some
of you rifle folks would like some insight. Ever bore-site a rifle before? Ever
wonder why when you made the adjustments for windage and elevation they seemed
to work backwards? If so, read on bunky, I have the explanation.
First, just for giggles and grins, lets do a
quick review, and all get on the same page. The big glass at the front of the
scope (that's the end towards the muzzle) is called the Objective Lens. The
glass at the rear (that's the end toward the butt) is called the Ocular Lens.
In between them is the Tube. Inside the Tube, we have a bunch of stuff. If your
scope is a variable power, like maybe a 3.5x10 or 3x9, there is a lens set
inside the tube that moves back and worth when you adjust the power which
changes the relative size of your viewing area. There is a reticle (in redneck
talk we call this a "cross-hair"). Then there are those windage and elevation
turret/adjustment knobs on the outside that move something on the inside when
we turn them. There is also a lens set called the Erector, to get that viewing
area right side up when we look through the scope. Sometimes the Erector is
actually a part of another lens set or has a dual function, but that's not
important to our discussion here. |
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Notice the
location of the Reticle, it's like in the back just inside the Ocular lens.
It's no where near the Windage and Elevation Knob adjusters. And there lies
what you may not know and why when bore-sighting, things seems to work
backwards. The reticle never moves when you make sight-in or compensation
adjustments. The reticle is fixed, as in mounted solid, never moves. Before I
proceed let me qualify this, it never moves in American design scopes and most
import scopes. There are a few that it moves in, but they are the exception to
the rule and I will explain why later. For now, let's just assume they don't
exist, because you probably have a Bushnell, Redfield, Tasco, Nikon, Leupold,
Bausch & Lomb or similar popular scope and these all work as I am
describing. When you turn the Windage or Elevation adjustment knobs you are
actually moving a lens set inside the Tube, not the Reticle (cross-hair). So
when making these adjustments instead of moving the Reticle as a reference, you
are actually moving your vision plane, that is….how you see the target in
relation to that fixed Reticle. It's actually bending the light (the light is
what carries the vision of a target to your eye) up/down, right/left as to how
you see the target in relationship to the Reticle.
As you make adjustment for windage and
elevation correction from a group that you shoot on paper, everything works
normally. But when you sight down your bore (that should actually read "through
your bore") and then turn the adjustments, that's when things get a little
fuzzy. Now for those that have not bore-sighted a rifle and scope let me do a
quick "how-to"……
Set your rifle up
on a sturdy rifle-rest or sandbags. Remove the bolt. Look through the bore (the
long hole in the barrel with those little spiral thingies inside, you know
where the bullet travels when fired!) and move the rifle around until you have
the bulls-eye target in the center of the bore. Now, once you have this
alignment, DON'T MOVE THE RIFLE. Move your eye up so you can see the reticle
(cross-hair). If it's not centered on the target you need to adjust it until it
is. Let's say for example, with the bore lined up, the Reticle is higher than
the bulls-eye. To adjust the elevation you need to turn the Elevation Adjuster
counter-clockwise as if you were loosening a bolt. This is the same direction
that the arrow indicators on your scope will tell you to move to adjust for a
higher impact, but that is the direction you must move to get the Reticle down
and aligned with the bulls-eye. [ by the way, if your
rifle is currently sighted in, don't go changing it just because when you look
down the bore the Reticle doesn't quite align with the target. Bore-sighting is
only a rough start-up to sight-in….if your gun is hitting what you aim at
leave it alone, say's Uncle George! ]
So…..when bore sighting, Up is Down and
Down is Up, just like Left is Right and Right is Left! I know, why do things
have to be so damm complicated. But look, here is the Redneck
method…..move the cross-hairs in any direction….it doesn't make any
difference which direction, just move it. Now, if it moved the wrong way,
adjust it back the other way! The only difference with the Redneck method,
Murphy gives you a guarantee you'll go the wrong way first almost every
time!!!!
Now if your confused don't blame me,
I don't design scopes, I just figure out how to use them and I didn't force you
to read this information, so actually we need to blame you!
Earlier I promised I would explain the
difference between most scopes and a few exceptions. If you have a variable
power scope you can test your own rifle scope and determine if you have one
that is "most" or if your scope just happens to be the exception. Adjust your
power to the lowest level. Align it on a far off target of some type. While
looking through the scope reach up and turn the power ring to full power. As
you do this, the target you selected will appear to get bigger as you increase
power, but the Reticle (cross-hair) will remain the same size. You have a scope
that is among the "most" category. If when you increase power the target gets
bigger and the Reticle ALSO gets bigger, your scope is the exception (or maybe
you have been tipping to much holiday cheer). My bet is, yours is like all the
rest of ours, in the "most" category.
Why
would there be a difference you ask? And a very good question. Long ago scopes
were made to work like the exceptions. They were changed for various reasons
but the primary one was perception! Some hunters didn't like how the cross-hair
grew huge when they turned up the power. Some ingenious designer changed the
location of the cross-hair and fixed the issue. Seems like more than just some
liked it, because before long our genius was getting all the sales until other
manufacturers followed in suit, soon becoming the new standard which holds to
this day.
Before there were variable power
scopes there wasn't much of a difference where the Reticle was placed, and most
Reticle's were placed as a part of the windage and elevation adjustment or, in
or near the Erector Lens. When scope manufacturers started to put variable
power zoom lens in, because of design restriction the best place turned out to
be just ahead of the Ocular lens in the back. That meant the Reticle was in
front of the variable power lens set, and as the target got bigger or smaller,
so did the cross-hair. To fix this problem, they mounted the cross-hair between
the variable power lens set and the ocular lens set. So in effect you first see
the Reticle, then the target. Because the Reticle is on your eye side of the
variable power lens, only the target grows in size when turning up the power or
it gets smaller when turning down the power. And there you are boys and girls,
a piece of history…..
With this change
came some side benefits, one of the biggest was ease of design and
manufacturing for the scope makers. While we're here, do you know what
Reticle's are made of? Most of them are made out of some type of metal, some
plastic and because of advancement in manufacturing miniatures in recent years,
some of the higher priced scope are using glass! That's right glass with the
cross-hair etched onto it. Spelled like in precision laser etching. Most likely
this will be a trend for other scope manufacturers in the future.
Now there are some new scopes being
introduced using the old Reticle placement, and the manufacturers are spouting
new advantages, but that's another story for another day. For now, make it easy
on yourself and forget everything I said……hell I'm confused enough as
it is!!! |
