View Full Version : Zeroing scope at 9x or 3x - any difference?

February 20, 2014, 04:49 PM
I was just curious, does it matter where you had your magnification while zeroing? I figured since the cross hair is in the center that it wouldn't matter one way or another, but I wanted to make sure this assumption is correct.

February 20, 2014, 04:53 PM
I always zero on the highest magnification. That's the way I was taught and the way I've always done it. I couldn't tell you why besides that's the way I was taught. Lol

February 20, 2014, 04:56 PM
Some scopes have a mark on the dial to zero on that mark and it should be good on any setting. If it dont have the mark I just get somewhere near the top and set it there.

February 20, 2014, 04:58 PM
It often depends on the scope.
For some, the reticle changes size with the power.
For others the parallax, (if the reticle seems to move, relative to the target when moving around behind the scope), might change with changes in power.
Some recommend zeroing with the power setting you will be actually using for the distance being zeroed.

February 20, 2014, 05:10 PM
I've always zero'd them at their highest power. Have been told to do it that way and have read directions that came with scopes that said to do it that way. Don't know if it's a mechanical thing or if it's just because you can see the aiming point of the target and your movement better.

Art Eatman
February 20, 2014, 08:15 PM
I sight in on the highest magnification, and then check that zero on the lowest magnification. I hunt on low magnification, for better field of view.

So far, no problem with any Leupold I've ever used, the most common brand of variable I have.

February 20, 2014, 08:43 PM
There could be small differences in the point of impact at a different setting than the one you used to zero the rifle. This is less of a problem with quality optics than cheap ones, but even with good scopes you might see very minor differences. Most people either don't have rifles accurate enough, or can't shoot well enough to notice it. Normally only highly skilled shooters with expensive target guns will ever notice the difference.

Like most have said I zero at the scopes highest setting than double check on the lowest setting where the scope stays 99% of the time. I figure if it is off by .5 MOA on the lowest setting I'll never notice the difference at 100-200 yards. At longer ranges I go straight to the highest setting where I know everything is zeroed. I never mess with any of the settings in between lowest and highest.

February 20, 2014, 10:26 PM
I had a simmons 3x14 (?) that would change POI 4" at 100 yards when shot at 3 and the 14 power. I sent it back for a new scope.

Most quality scopes should be very close from one extreme to another.

I now split the difference and with a 3x9 use the six power setting. That way if there is any change it will be very little. My Leupolds do not seem to change from low to high power. Nor do my Nikons or one Burris own. It has only been with the budget scopes I have had this problem. And none have been as bad as the scope first mentioned. And that scope was from the early 80s when simmons first came out. I don't know about their newer stuff.

Sea Buck
February 26, 2014, 10:09 PM
The cheaper scopes may exhibit a wandering zero between max and min magnifications. Some will, some will not, sort of luck of the draw. You pay for what you get. I have had a Tasco Pronghorn bought in 1998 that was and is super. I have had Bushnell's that fell apart. A Simmons 3-9 wide view went from my 06 to my AR for coyote work and is great. I now use Leupold exclusively.

February 27, 2014, 10:28 AM
I have always split the deference to. Glad to hear that someone dose to
I have been told that with max zoom there is more parts moving witch means more room for error
I have also notice that cheaper scopes tend to move a lot more when zooming in and out then high quality scopes. I use Nikon and notice very minor movement

February 27, 2014, 11:45 AM
I think it all depends on your scope. I have a mil dot on my 308; ranging with mil dots only works on 12x so that's what I sight in at. But if I'm shooting for group, I crank that baby all the way up to 25x!

March 2, 2014, 08:26 PM
If you zero in using the highest power, remember to turn it down to the lowest power after you are done. The next time you go hunting and the scope is set at 9X, I guarantee the first game you see will be 50 yards away. By the time you find the target animal, it will be gone...

March 3, 2014, 07:58 AM
On vari power scopes the field of view decreases as the power is increased. I do most of my hunting in wide open country so most of my scopes are sited in at the highest power and not changed. Except a 6.5- 20 X AO scope which I have turned down when shooting prairie dogs on hot days.

Art Eatman
March 3, 2014, 09:18 AM
Seems to me to be important to know whether or not the point of impact is different at low magnification, compared to high magnification. That's why, although I do my sighting in at "max mag", I then compare POI at "min mag".

If you mostly use the low magnification when hunting, it seems to me to be worthwhile to adjust the scope, if that's necessary due to a difference in POI.

March 3, 2014, 10:04 PM
Seems like a no-brainer, based on simple physics to me.

With a typical SFP optic, higher magnification results in a more precise point of aim, which by default equals a more precise "zero".

If it didn't, what would be the point of high-power optics?

At 10x, the center of the crosshairs might completely cover a target at 1000 yards. You're essentially "guessing" when you're centered. Fine for minute-of-man, not for accurate point of aim at dead center of a target.

March 4, 2014, 10:29 AM
On a 3x-9x I always sight in at 6x this way if there is any movement when increasing or decreasing magnification it is held to a minimum. This is what I read about years ago but with the advancement in quality of scopes it probably doesn't really matter.

March 4, 2014, 11:45 AM
I don't know that it is much of a problem today, but years ago, the mechanical axis and the optical axis were not held to close enough tolerances to prevent POI changes when zooming from low magnification to higher magnification.

I think it is not so much a problem today with name brand scopes. It could be a problem with some.

The only way to tell for sure would be to use a collimator and zero the scope at infinity and "buck" in at 3 feet or so and run the line of sight at various distances and check the parallelism.

The equipment to do that is very expensive.

One way you COULD get an idea is to secure the scope on a bench and adjust it to be zero horizontally and vertically at 100 yards at the highest power.

Then, if you can make sure the scope does not move, change the magnification and watch to see how much vertical and horizontal displacement occurs when changing power.

I am going to guess it will not be much.

Bart B.
March 4, 2014, 09:05 PM
Once the rifle's clamped in solid with the scope on something down range, just change the power and see if the reticule moves around in the target area. You don't need to twist the E and W knobs or even the range focus one. The reticule typically moves in a figure 8 pattern or sometimes the letter C or S patterns. It all depends on the mechanics of the two lens group barrels sliding back and forth at the back end of the scope right in front of the eyepiece. This is for rear focal plane scopes.

Front focal plane scopes can change reticule position on target if the objective lens' group moves irregularly when it focuses for range.