help with range estimation feature

ker2222

Member
Joined
Sep 5, 2004
Messages
23
The new leupold VX-III scopes with the wide duplex have a "range estimating" feature. The bottom post has a cutout that you center on a 16'' target and then zoom in on until the target then fills the cutout--numbers on the back of the zoom ring then estimate your range for you.

Has anyone tried this system???? If so, how did it work. More importantly, for me at least, is this: If you went through the same process with an 8 inch target, would you be able to estimate your range by doubling the range given for a 16 inch target???

Any help would be greatly appreciated.
 

royinidaho

Well-Known Member
Joined
Jan 20, 2004
Messages
8,940
Location
Blackfoot, Idaho
My answer would be to do the math. Don't mean to sound trite but there is much to be gained for "doning the math".

Work it out for 8" then 2X16 or 32", which is the brisket to withers of a decent sized elk.

It'll be fun and you'll learn alot.

Went the same route with a mil-do and different power settings.

It really gets you familiar with what you are doing. You'll get a "feel" for it pretty quick.

But not to rain on the parade, I ended up getting a LRF.
I couldn' handle all the brain work with a live target out there. When its time to shoot, its time to shoot.
 

sscoyote

Well-Known Member
Joined
Feb 26, 2003
Messages
1,284
Location
Pueblo, CO
What you're talikng about is a subtension calculation, all based on simple ratio and proportion calcs. As magnification changes so does reticle subtension in a linear manner. The calc. is inversely proportional tho, because the subtension decreases as magnification increases.

Fortunately since we aren't actually changing magnification here it's simply directly proportional. Suppose the 16" target is 600 yds. away, u have the following equation-- 16/600=8/X, so X=300 yds.

Another way to compute it is too use a modified mil-dot ranging formula, i.e.-- target size in inches X 100/reticle subtension in inches = X/ # of reticle units, or 16 X 100/say 2.7"= X/1 reticle unit== 592 yds. Now an 8" target fills that same 2.7" gap measurement, so now u have 8 X 100/2.7= X/1 reticle unit== 296 yds.

All reticle subtension formulas are based off the same linear concept, which makes them extremely flexible to fit many different scenarios, and fun to play with. The Leupold system is based on a 100 yd. gap measurement (x-hair-plex post) of 2.7" for a 16" target @ 600 yds. @ THE HIGHEST MAGNIFICATION since 2.7" X 6== 16.2", then as the magnification is lowered the subtension gets bigger to "gap" a 16" back-brisket deer that's closer. Hope this isn't too confusing an explanation.

[ 10-31-2004: Message edited by: sscoyote ]

[ 10-31-2004: Message edited by: sscoyote ]

[ 10-31-2004: Message edited by: sscoyote ]
 

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