re-centering scope reticle using a mirror?

N

NativeCraft

New member
I think I recall reading somewhere that you could re-center a scope's reticle by placing the front objective against a mirror?...rather than counting total clicks and dividing by two, etc..
Anyone else hear of the same thing or is old age starting to take me down?
 
From Leupold's answer guide....

Quote:
Centering of a scope's adjustment dials
The elevation and windage adjustments of a scope are easily centered. Place a small mirror against the objective end of the scope. That would be the end farthest from your eye as you look through the scope. Make certain that the mirror is large enough to cover the entire objective. It must also be flat against the objective. With the scope's power selector ring set at the lowest magnification, look through the eyepiece as you would while aiming at a target. If the scope's windage and elevation adjustments are off center, you will see two images of the reticle (cross-hair). To reach the center of the adjustment range, simply turn the elevation and windage dials until you see only one image of the reticle.



http://www.leupold.com/resources/MyInfo81/Answerbook/Answers/668.aspx
 
Whow this is really cool!!!

Yesterday I needed to recenter a scope and remembered this thread. So out came a mirror, I slapped it on the objective and at first I couldn't see a thing, but after looking a bit more by god I could see 2 cross hairs. A twist here and a twist there and the scope was recentered. This is a very cool, increadably fast method of centering a scope. Thank you all and thanks Leupold.
 
I was returning a scoipe that didn't work well for my intended purposes. It only seemed right to recenter it. Over the years when changing a scope from one rifle to another it hasn't been a big deal for me to just sight in again, but with an easy method like this to recenter a scope, why not? ....... Maybe the confusion for you is something else though. On modern scopes the cross hairs always look centered, but the guts are not centered in the ... well in the middle of the scope. Recentering the cross hairs gives you a good starting point on a new or different rifle. Also when you have a rifle with adjustable bases quite a few shooters like to take advantage of the superior optice available in the very center of the lenses, they like to adjust the base for windage rather than using the cross hairs. Centering gives you the very best optical portion of the glass.


NativeCraft - I did the bright light thing, but also wondered if that was necessary so I tried different lighting conditions. I believe the light used is actually the light comming through the back end of the scope. Light goes in, bounces off the mirror back at you showing the cross hair in the scope. You see the reflected image and the true inage. When the two meet the scop0e is centered. Once you get the hang of it this always works reguardless of lighting conditions. My initial problems was caused by using the wrong side of the hand held mirror. The mirror had a standard glass and a magnifying glass. The magnifying side didn't work well at all. /ubbthreads/images/graemlins/smile.gif
 
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I recenter a scope before I mount it. That way when I look through the culminator I can "somewhat" tell how off the rings are. If the mounting platform is WAY off I'll work on tweaking that so I don't run out of scope adjustment when zeroing.
 
I have been using this method for quite some time. I allways try to adjust my scopes using the bases. As MJM said, it gives a clearer image when the reticles are centered in the scope. You can actually check the scope while on the rifle to see how far off the bases are by how much the reticles are off center while zeroed.
 
I just checked three scopes I have here, two I'm getting ready to mount and all three are now recentered. The brand new one was the farthest off center. Very cool post.
 
Quote:
The closer to center you can keep a scopes erector tube "after" zeroing, the more elevation travel it will have
RR



If you have a scope with a total of 40 MOA of elevation, and the scope is "centered" when zeroed at 100yds, then you only have 20 MOA of elevation that is usable... with a 308 match round, that won't take you to 700 yds... you'll run out of elevation at around 675 yds.

But if you set up the scope with the 100yd zero at just above the BOTTOM of the elevation, you get most of the 40 MOA as usable "UP". If you set the scope up just 2 MOA off the bottom with the 308, the maximum range is now over 1000 yds.

Most serious long range shooters mount their scopes so that they get the most elevation travel possible.

I have a 50BMG rifle, and on it is a Bausch & Lomb 10x with 148 MOA of total travel. It is set up so the 100 yd zero is 2 MOA off the bottom of the adjustment. Set up this way, I have 145 MOA of up elevation available.

As to the "sharpness"... any of the middle to better quality scopes are sharp from edge to edge - try it... adjust the elevation to the bottom and look at something with fine detail, and do the same at the middle and top of the elevation range, and you will NOT see a difference.

You might see some difference with junk scopes, but with junk scopes, you are getting a soft image anyway (and why are you using junk scopes???).

And... as a last thought/question... "if" it were true that your scope was sharpest with the reticle in the center, why would you want to use the sharpest part of the scope for shooting at 100 yds, and leave the 400-500 yd shots at the blurry part? It would make more sense to set the scope so the blurry part was at 100 yds and the sharpest part was being used at 400-500 yds. NO???

But this is not an issue, because a decent scope is sharp from top to bottom of the elevation.

.
 
what I was refering too, I see now it wasn't explained well, was that if your l,r adjustment is just off the stop when you make zero, the u,d adjustment won't have as much room to move. to get full 40 MOA of travel on the vert adj in that scope the horiz. adjustment must be close to center.
RR
 
Quote:
what I was refering too, I see now it wasn't explained well, was that if your l,r adjustment is just off the stop when you make zero, the u,d adjustment won't have as much room to move. to get full 40 MOA of travel on the vert adj in that scope the horiz. adjustment must be close to center.
RR



Yup.. that is true. I center, L/R, the bases first (if necessary), to be able to do the rest.

.
 
Now for you folks doing a remove and replace on a sighted in scope, who have a barrel spud type collimator, first install the collimator in the barrel very carefully and note where the crosshairs indicate "0". Carefully remove the old scope without moving the collimator and install the new "optically zeroed scope (that you used the mirror trick on) and when the new scope is okay for eye relief, and level, and tightened down, adjust the crosshairs to the collimator position noted previously. Of course you can use the rear base windage screws on Redfield type bases for initial scope windage if it's off much from optical zero. This is called mechanical zero, and works on Millet angle-locs too. This gives you the most windage adjustment capability. Most times it's near perfect. Good shooting. /ubbthreads/images/graemlins/smile.gif
 
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