Guide to Scopes By Tom Eby March 22, 2004 This guide was originally an interactive presentation given at the January 22, 2004 meeting of the Twin City Rod & Gun Club. The author claims no special expertise and the opinions expressed are based on his own research and experience. The Intent of the presentation was to provide an aid to the selection and use of telescopic sights.
Ha! Another great shot Magoo! Wall-hanger for sure! No need for a fancy scope on this old smokepole!
Or for many of us older-type Sharpshooters THEN And..NOW!
Basic Parts of The Rifle Scope (American Style) Forms Image Windage Inverts Image, X-Hair Elevation Magnifies Magnifies Knobs W & E knobs move Image up/down, left/right on X-hair Reticle is in 2 nd Image Plane, Reticle does NOT move Image only is Inverted & Magnified
Basic Parts of the Rifle Scope (European Style) Reticle is in 1 st Image Plane, W & E knobs move the Reticle. Image AND Reticle are Inverted & Magnified Simultaneously by Lenses
Magnifying the X-Hair? American vs. European Optics American European Reticle in: 2 nd Image Plane 1 st Image Plane Mag. Setting
Optics - European
EXIT PUPIL What is It? Diameter of the Light Shaft Exiting the Eye Lens (Ocular) How to Calculate? Objective Diameter / Magnification Example: for 3x9 40mm Scope: At 3x : 40/3 = 13.3mm exit pupil At 9x: 40/9 = 4.4mm exit pupil Hold scope at arm s length, point to light, image you see is the Exit Pupil
SIZE OF MAX. IRIS OPENING vs. AGE AGE MAXIMUM IRIS OPENING <25 7.0 mm 30 6.5 35 6.0 45 5.5 60 5.0 80 4.5 Bottom Line: Gets harder to see in twilight as you get old.
EXIT PUPIL vs. IRIS OPENING Variable Scope with 50mm Objective 7mm exit pupil Matches 7mm Iris of 25 year old eye -- 7x setting 7mm exit pupil Larger than 5mm Iris of 60 year old eye at 7x setting - Wasted Light! --Set scope to 10x, image is as bright as at 7x.
PARALLAX What Is It? Target Image Plane Is Not Coincident With Crosshair Plane Most Rifle scopes set for Zero Parallax at ~100 or 150 yards. Corrected by Adjustable Objective (AO)
PARALLAX Important Over 10-12x Magnification Causes Error in Bullet Point-Of-Impact, Up to ½ at 100 Yards Check for Parallax by Moving Your Head around while Looking thru the Scope aimed at a Target But Focus Reticle First! If the Crosshair Appears to Move in Relation to the Target, Parallax Exists
Basic Parts of A Telescopic Rifle Sight
PARALLAX How To Correct??
Sighting In 25 yards 100 yards Scope Actually Points Down! Minute of Angle 1 at 100 yards
Rifle Scope Optic Reticle Adjustment (1 st Image Plane)
FEATURES TO LOOK FOR: Most American Scopes: 3.0 4.0 inches European Scopes: 2.5 3.5 inches Rubber Eyepiece Rims Help Prevent Scope Cuts!
Optical Coatings On The Lenses
Coatings on Scope Lenses BEST: FULLY MULTI-COATED GOOD: MULTI-COATED OK: FULLY COATED Ugh COATED As a Rule.More Coatings, The Better!
Loss of Light is Due to REFRACTION Formula: ((1-ρ)/(1+ρ)) 2 = Reflection Loss ρ = index of glass (1.5) /index of air (1.0) Wow!
Coatings Reduce Loss of Light Much Better!
Reticle Types Leupold alone offers 17 Styles! pick Take ur Illuminated
Mil-Dot Reticle Not Military Dot! Mil = Milliradians = 3.6 at 100 yards = 1 yard at 1000 yards, etc.
Range Estimation with Mil-Dot Reticle Formula: (Height of Target in Yards) x 1000 ------------------------------------- = RANGE # of Mils Subtended Example: Deer = 1.25 yards high (45 ), 3 Mils 1.25 x 1000 ------------- = 415 yards 3 mils
So: 1 yard x 1000 ---------------- = 500 yards 2 mils Bambi is 36 Tall at Back - Subtends 2 Mils - Range = 500 yards
Use Mil-Dot Master to Calculate the Range & Holdover for your Rifle & Load Or. 18 Inches -- Set Magnification to Bracket Deer & Read the Range off the Scope (Or just cheat and use a Laser Rangefinder)
1 Spring Posi-Lock Springs Ring Inserts 2 Springs Posi-Lock
Nitrogen Purged - Prevent Fogging Good Eye Relief Adjustable Objective for Parallax if > 10-12x Fully Multi-Coated Lenses Strong Mechanical Construction - Costs $$$ Reproducible Reticle Settings - ¼ or ½ MOA Adjustable Focus Eyepiece Optics sharp to edge of Field Temperature Compensated
Basic Setup and Mounting Clean Rings, Bases of any oils Square up Rings to be Parallel - Avoid Stress on Tube - Use Dowel or Leupold wrench Loosely Mount Scope in Rings Adjust for Eye Relief Keep X-Hairs Orthogonal Snug up Rings - alternate tightening Check scope alignment as you tighten
Mechanically Center Up the X-Hairs Adjust Eyepiece focus for your Eye - Reticle Must be Sharp! Bore-sight (Fred will Help) or. Target at 100 Yards Bolt-Action Rifle
Caps Flip-Up Anti-Reflection Caps
Adjustable Objective
..RESULTS Namibia, Africa 550 meters 7mm/08
Mil-Dot Master Bullet Drop Read off Mils
Why a Scope? Magnify Small Targets Take Advantage of Rifles Accuracy Extend Low Light Visibility Range Finding w/appropriate Reticle Ready Spotting Scope Convenient Carrying Handle
COST COMPARE Schmidt&Bender Zeiss (German) Kahles Swarovski $900 - $1800 Leupold Nikon Burris Weaver Zeiss (Conquest USA) $350 - $1000 Simmons Bushnell, Bausch & Lomb, Bushnell etc. $150 - $300
COST is PROPORTIONAL to QUALITY
U.S. OPTICS $3000 +