MilDot Surprise - Trick or Treat

[Lapua40X]

Finally got all the parts assembled on my new build and ran out to the range to set up sighting.
In my previous experience, MilDot spacing is typically 3.6 inches c/c on max. power at 100 yards. (1 mi l=.36 x 100 = 3.6)
Imagine my surprise when I found my new Zeiss Conquest 6.5 - 20 x 50 was closer to 2 inches. Naturally, I figured it was a manufacturing error - WRONG!!!!!!!!!!
When I called Zeiss they informed me that their MilDot spacing for this scope at max. power is designed at 1.8 inches.
Well, at least my estimates of the spacing on target were pretty close 8)
OK, it's true I can still use the scope for ranging. But the shooting world I grew up in used the standard a "Mil" at 100 yards still calculates to 3.6 inches, regardless of who makes the scope.

http://www.mil-dot.com/articles/the-mildot-reticle

 

[mao0720]

Many second focal plane, mildot scopes use a lower than max power for the correct "mill" magnification. Example would be a 2-16x Bushnell 6500 has the 10x mark highlighted red so that you know thats where the milldot are spaced correctly. Why scope manufactures dont just make the mills correct on max magnification is beyond my knowledge.

 

[dmork98]

Welcome to the world of ZIESS!!!! So sorry..... That is why I will never own another.

 

[Buzz]

They'll usually use a factor of max power so the estimation can be done at different power levels. At 10x you're at 3.6 and at 20x you're at 1.8. If it was set at 20x then 10x would be 7.2 and I don't know how useful that would really be. I don't recall seeing a higher magnification hunting scope with the ranging being set for the maximum magnification, so I don't think it's anything oddball from Zeiss.

 

[Buzz]

There is a nice ffp bushnell for sale for $650 on this board if it's something you can't live with though.

 

[wwbrown]

You just found out what many hunters find out when they use their ballistic compensating reticles on variable power scopes they miss because they are only calibrated for one power unless the reticles are in the first focal plane (FFP). Most US made scopes are second focal plane scopes and the reticles can only be used for ranging and bullet drop at one range and that is usually highlighted somehow on the power adjustment ring.

You can easily tell whether your scope is FFP, if the reticle seems to get thicker and heavier as the power is increased it is a FFP scope.

 

[Erik Cortina]

Nothing wrong with the scope, backing the power to 10X should make it work normal.
It will make 1.8 twice the size, so it would make it 3.6

 

[NateHaler]

Figuring out which magnification setting on a 2nd focal plane scope equates to "standard" mildot spacing isn't a big deal, but it pays to check for yourself instead of simply relying on the mfg's specs.

Put a yardstick at a measured 100y. Tape it onto your target backer, for example before you start in with "shooting sub 1/2 MOA groups all day long if you do your part". :-X

Then, while peering through your scope, determine when/where your mildots equate to the prescribed spacing. Many mildot reticles (perhaps most of them) have four dots on each axis of the reticle, and then a much thicker reticle section on the outer portion of each axis. At 100y, based on the reticle just described (albeit poorly), the yardstick should span the reticle between the two junctions of the thicker/thinner portions on each axis. And each adjoining dot should line up at 3.6" center to center.

I have various mildot scopes, most of which are 2nd focal plane. I mark the magnification ring with a tiny dab of paint to denote the standard mil spacing, if in fact the scope doesn't have such a mark from the factory (which many of them do, conveniently).

In my experience, many 2nd focal plane scopes don't feature standard mildot spacing at maximum magnification. The Sightron SIII 8-32, for example, equates to standard spacing at 24x. But their SIII 6-24 equates to standard at 24x.

Last but not least, you may think that mildot reticles are primarily for estimating distance to target, but I use my mildots much more frequently for effectively adding elevation to the scope's internal adjustment range. Whatever works. 8)

 

[Lapua40X]

Checking the calibration of the reticle is a very important aspect, no matter what the brand or model or price-tag.
...
A "tip/trick" to Mil-Dot scopes (3.6" sub-tensions):
I myself like and use MOA, and will dial a Mil-Dot until the sub-tension comes out to MOA, mark that point, and use them as MOA reticles instead of Milliradian.

That's an excellent idea. I got stuck in the miliradian thing and never considered looking at the dots exclusively in terms of MOA; although, in reality, that's typically done in the shooter's head once the miliradian data is factored into the shot. Working out the spacing at MOA and forgetting about the mil just might be the best solution to handling assingment. Thanks, Donovan .......

 

[sscoyote]

A little late to this party...but I also check reticle subtensions on all my reticles, even 2X pistol scopes with plex-style reticles get measured. It's fun to apply subtension for rangefinding and downrange zeroing. On variable power scopes reticle subtension is ~inversely proportional to magnification. In fact some ballistics program use this concept to adjust downrange zeroing with multi-stadia reticles including mil-dots. Gerald Perry started it with Exbal then Nightforce contracted him to do their ballistics programs, and now Nikon Spot-On also uses it, and some others now i think.

I always reticle-range at the optic's highest power and usually use the mil-dot for windage apps.

Nikon usually uses 12X and I think Bushnell usually uses 14X.

 

[CJ6]

Burris is at 14X with their mi-dot (8x32)