Guys,
I truly do not know that much about optics. I just understand how to use them to there full advantages and try to pass that down to my students so they are educated in what does what and how.
jackh said:
now, what is parallax adjustment? and what is exit pupil?
Lets talk about what parallax does to a shooter, the info I am about to talk about is a easy way to visualize the issue, but will not be spot on in the mechanical aspect of what happens.
A parallax adjustment knob is found on the left side of most optics. This knob is mistaken as a focus adjustment do to the sight picture the shooter sees going in and out of focus as he / she adjusts the knob back and forth.
What parallax basically is, the image of the reticle, that is adjustable, floating around the object the shooter is aiming at.
Part 1.
Check this out, when you dial with a elevation or windage knob, all you are doing is moving the housing the reticle is built in, up, down, left or right be it, a piece of glass, or wire. So when you do this, your Point Of Aim "POA" is moved. When your POA is moved, so does your Point Of Impact "POI"
If you line up your POA to your POI you have something called a ZERO. Do to ZERO adjustment to get the bullet to hit where you are aiming at.
In the process is getting your POA to move around, you screw with the location your eye is seeing the reticle's image at in the lens of the rifle scope.
Part 2.
Since a lens is curved, if you look in the middle of the lens all is cool, if you look at the 6 o'clock location within the center of the lens you will not have the same clear and crisp picture as if you where looking at the dead center. This is where the parallax adjustment comes in to play.
By adjusting the parallax you clean up the image of the object you want to shoot at, and place the reticle on the same FOCUS PLANE.
TEST
Do this. Get on your rifle, get solid position built and have your reticle aimed at the target. Then lift your head up just enough so you do not have a cheek weld on the stock.
Now move your head around in a small circle. If the reticle moves and dances around the target, your parallax is off do to the target and the reticle not being equal on the same FOCUS PLANE
Once you get your parallax set, you can move your head in a circle and the reticle is dead on the target and does not dance around do to the target and the reticle are now both on the same FOCUS PLANE
Why do I need this parallax crap?
Well its simple, you do not NEED parallax if you do not plan on engaging your target will precise shot placement "with in 4 MOA"
I have seen shooters go from a 5 MOA group @ 100yds to a 1 MOA group by adjusting there parallax and get it set right.
Keep in mind, a correct parallax setting needs to be done per distance you shoot at. So if you are shooting at 100yds then 600yds, you might want to adjust for parallax.
Or if your cheek weld and marksmanship skills are good, you can run with a 300yd parallax setting and be good to go.
Most optic brands have adjustable parallax models of rifle scopes. If I buy lets say a Leupold Vari-III 3.5-10x40mm it has a fixed parallax of 100yds.
Well that sucks I think, I send mine of the the custom shop to get the fixed parallax adjusted to 300yds. A 300yd fixed parallax is a great distance to run in a non-adjustable rifle scope. Due to @ 1000yds I am only floating around with 1.5 MOA of parallax. So for me, thats all good.
John