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Newsgroups: AIRGUN.LIST
Organization: Mac-1 
I took the liberty of reposting this from the Airgunletter forum as I
thought the airgunlist would appreciate it. I'd say it makes the answers
to FAQ's file.
Later
Tim
Dick Thomas-Premier Reticles 
: 1) Materials used to build scope.
: 2) How various lenses are retained in the optical system
: 3) Erector tube design and construction.
: 4) If a variable power scope the tolerances between parts that zoom.
: 5) Erector tube return spring design and material used.
: 6) Reticle design and material used.
: Let me elaborate on each of these points. Any one or all of the above
determine the quality (or longevity when used on an
airgun).
: 1) Many times dead-soft aluminum is the material of choice. It costs
less and somewhat easier to work with. Ever see the
main tube crush on a scope when the scope rings are tightened a small
amount? When it is done right a 6000 series of
aluminum should be used. It is a much tougher aluminum. Think of it as a
heat treated aluminum. Sometimes a scope
manufacturer will refer to using "aircraft aluminum alloy". This
material us usually a 6061 T6...lightweight and tough.
: 2) A short cut to retaining a lens in a cell is to roll a small
thickness of aluminum in behind the lens. It is called "rolling the lens
in". This is fine on the smaller lenses in the system, although when a
dead soft aluminum is used the lens will eventually loosen
with reverse recoil. The biggest lens in the system, the objective lens,
if often rolled in and will usually fail with extended
recoil. When it is done properly a threaded retaining ring is screwed in
behind the objective lens to prevent it from loosening
with recoil.
: 3) The erector tube is the tube inside the scope that holds the
erector lenses. The erector lenses are the part of the optical
system that erects (turns the image right side up). If it is a fixed
power scope the lenses are at a fixed or permanent spacing in
the tube. If it is a variable power scope these lenses are ultimately
connected to the power ring and zoom back and forth,
increasing and decreasing the spacing, thereby changing the
magnification. Whenever you made a windage or elevation
correction you are moving this erector tube and the lenses inside. You
do not move the reticle. It is stationary just in front of
the eyepiece. What happens when the adjustment is given is the image in
the optical system is moved relative to the stationary
reticle. 
: How the erector tube is attached to the scope main tube is what
determines how repeatable and dependable the scope is.
The most accurate design has a type of ball and socket design. The
erector tube has a radius that engages in a socket on the
main tube. This assures a minimum of resistance when the erector tube is
adjusted with the elevation/windage adjustments. A
production short cut often taken is to simply attach the erector tube to
the main tube with a couple of screws. When an
adjustment is made the main tube actually flexes. It also flexes each
time a shot is taken because the erector tube, for an
instant, moves away from the face of the elevation/windage adjustments
and is then pushed back by the erector tube return
spring. When this is done over and over again metal fatigue takes place
and the scope will not hold zero.
: 4) Tolerances between the erector lens assembly and the erector tube
must be almost zero. If not the image moves relative
to the reticle and causes shifts in point of impact. Most less expensive
scopes have terrible tolerances here.
: 5) Erector tube return spring (they hold the erector tube against the
faces of the windage and elevation faces)may have an
incorrect shape or weak tensile strength. These springs fatigue with
repeated recoil. Quality scopes have two return springs
with a proper shape and extra strong tensile strength.
: 6) Have you ever seen a broken reticle in a scope used on an airgun?
Inexpensive scopes use an etched/foil reticle. These
are mass produced from large sheets of stainless foil that is
approximately .0015" thick. When they are attached to the reticle
blank they must have the proper tension when cemented. If it is too
tight the shock of recoil will break the reticle. If it is too
loose it will whip at recoil and break. Quality reticles are made with
either glass or fine wire. If you have a reticle that has
broken your chances of it happening again and again are excellent.
: In short you do get what you pay for in optics. The lesser the cost of
the scope the better the chances of all 6 characteristics
mentioned being made the easy/cheaper way.
: Three additional factors should be considered when purchasing a scope. 
: 1) What kind of optical quality will I get? Poor quality, uncoated
lenes go hand and hand with the quality of target image. 
: 2) What kind of warranty do I get? Even if it has a limited warranty
why should you have to send it back for repairs over
and over. If the design is inferior to begin with what makes you think
the repair center can turn a pigs ear into a silk purse?
Quality scopes have lifetime warranties.
: 3) Finally it all comes down to cost of the optics. Of course you
don't want to spend more for the scope than you did the
airgun. This brings up the most important word when it comes to scopes.
It is "VALUE". Having seen the insides of scopes
for more than 50 years and seeing the flood of private label (scopes not
produced by the people selling it and not have much
control over the quality) starting in the mid 70's, to exploding to more
brands than I can even remember in the 90's, we
changed our policy in 1990 to not work on any brand of scope except
Leupold. All the production short cuts mentioned
above plus the fact that reticles were next to impossible to change in
the private label brands because they were "gluing" them
in. It costs less to glue it in than use a threaded reticle lock ring. 
: When we are asked to recommend a scope and we say Leupold, some people
give us grief because we also sell Leupold
scopes...why recommend a brand you don't sell?. Trust me when I say we
only sell, modify and do reticle changes in
Leupold scopes because we believe in them. They meet the criteria of
being the best scope for the money or if you like the
best "value". Some European scopes come close to having the quality but
because of the double to triple price are not a
good value. 
: Dick Thomas-Premier Reticles
-- 
MAC-1 Airgun Distr./McMurray & Son   Phone 310-327-3581 FAX 310-327-0238
http://www.mindspring.com/~airguns/  Hours-M,Tu,F,Sa 11:00AM-6:00PM PST
13974 Van Ness Ave.                  Tim McMurray
Gardena, CA 90249 USA                mac1@concentric.net
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