You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Eliminating Parallax
- Thread starter Bart B.
- Start date
Can an aperture rear sight with a -.5 diopter corrective lens have parallax problems?I believe parallax is an issue unique to optics, and does not occur with open or aperature sights that utilize no optical elements.
Does a barrel aimed with metallic sights always point to the same place on target regardless of how they may appear relative to each other and the target?
Last edited:
How are you defining parallax? I don't see how you could have parallax in metallic sights as the requirements for aiming with metallic sights pretty much rules out parallax by forcing the shooter's eye into proper position.
If used properly, metallic sights always appear the same relative to each other and the target. I'm not sure what this question means.Does a barrel aimed with metallic sights always point to the same place on target regardless of how they may appear relative to each other and the target?
Parallax with metallic sights exists when front and/or rear sight center is not on the line of sight between eye and target center.
With a good zero for target range, when front and rear sight centers are on the line of sight (LOS) from eye center to target center, shots so fired will strike the target center.
If front sight center is to the right of aperture center but centered on target upon firing, shot will go right because the line of fire (LOF) points right of LOS.
If rear sight center is to the right of front sight centered on target when fired, shot will go left because the LOF points left of LOS.
Shooter has to conciously correct front and rear sight alignmen to the LOS from eye to target.
With a good zero for target range, when front and rear sight centers are on the line of sight (LOS) from eye center to target center, shots so fired will strike the target center.
If front sight center is to the right of aperture center but centered on target upon firing, shot will go right because the line of fire (LOF) points right of LOS.
If rear sight center is to the right of front sight centered on target when fired, shot will go left because the LOF points left of LOS.
Shooter has to conciously correct front and rear sight alignmen to the LOS from eye to target.
Last edited:
If front sight center is to the right of LOS upon firing, shot will go right.
If rear sight center is to the right of LOS when fired, shot will go left.
If either of those are true then the sights are not zeroed. I don't see that as a parallax problem.
Another shooter may hold the rifle differently and a rifle zeroed for me may not impact in the same spot as someone else. And I see this as more of an issue with iron sights than optics.
Yes, I erred. Corrected the post. Thanks. Sometimes hard for me to explain. It's complicated.If either of those are true then the sights are not zeroed. I don't see that as a parallax problem.
It's equal both ways. I've observed this a few times shooting 4 man team matches with the same rifle and ammo.Another shooter may hold the rifle differently and a rifle zeroed for me may not impact in the same spot as someone else. And I see this as more of an issue with iron sights than optics.
Last edited:
Strictly speaking, that's sight misalignment.Parallax with metallic sights exists when front and/or rear sight center is not on the line of sight between eye and target center.
Parallax exists when the sight(s) appear to be properly aligned with the target but aren't because the shooter's eye is not properly aligned with the sight(s). That can't really happen with metallic sights.
Last edited:
I have demonstrated my reasoning is factual with a rifle hard mounted in place aimed at a target then moving front and rear sights so people can see what happens.Strictly speaking, that's sight misalignment.
Parallax exists when the sight(s) appear to be properly aligned with the target but aren't because the shooter's eye is not properly aligned with the sight(s). That can't really happen with metallic sights.
Also with a collimator and live fire exercises.
Bart B. said:I have demonstrated my reasoning is factual with a rifle hard mounted in place aimed at a target then moving front and rear sights so people can see what happens.
Emphasis added. What you describe above is not what I understand as a parallax problem in an optic.
I know I have a parallax problem in an optic when the optic is zeroed and the rifle stationary as I look through the optic and move my head, but not the rifle or the sights. Parallax will make the crosshairs appear to move on the target even though I know the point of aim can't actually be changing.
If I do the same with an iron sight rifle (move my head while the rifle is stationary), the front post and target move off center, so I no longer have what appears to be an aligned sight. That's not a parallax error because it isn't an error, but the iron sights doing what they are designed to do -- tell you when the back and front are or are not aligned to a spot on the target.
Last edited:
FrankenMauser
New member
Yes.Is parallax eliminated the same way with both metallic and optical sights?
The only way to eliminate parallax is to put the muzzle against the target.
LeverGunFan
New member
Parallax in a rifle scope exists when the target image is not in the same plane as the reticle. It can be corrected by refocusing the objective (front) lens so that the target image is corrected to the same plane as the reticle, such as on adjustable objective rifle scopes. Focusing the eyepiece does not correct for parallax, it corrects for refractive errors in the eye.
Since there is no target image produced by an open sight system, there is no parallax. A diopter lens in an aperture sight is used to correct refractive errors in the eye.
Since there is no target image produced by an open sight system, there is no parallax. A diopter lens in an aperture sight is used to correct refractive errors in the eye.
That's a parallax situation, not a parallax error. The parallax error is how far bullet misses point of aim when a parallax situation exists.If I do the same with an iron sight rifle (move my head while the rifle is stationary), the front post and target move off center, so I no longer have what appears to be an aligned sight. That's not a parallax error because it isn't an error, but the iron sights doing what they are designed to do -- tell you when the back and front are or are not aligned to a spot on the target.
We first must agree on what parallax is defined as by some standard; perhaps a dictionary?
https://en.wikipedia.org/wiki/Parallax
Last edited:
I don't disagree with your explanation of what happens when the sights are misaligned as you describe. I just don't think it fits the definition of "parallax".I have demonstrated my reasoning is factual with a rifle hard mounted in place aimed at a target then moving front and rear sights so people can see what happens.
I agree 100% with that definition of parallax.We first must agree on what parallax is defined as by some standard; perhaps a dictionary?
However, that can't happen with metallic sights because there are TWO components to the sights, not just a single aiming reticle. The eye, the front and rear sight and the target all must be in a line when the rifle is aimed. As soon as the eye moves out of line with the sights, the sights are no longer lined up with each other and so it's obvious that there's a problem.
In a system with true parallax, the reticle/aiming device does not show an obvious problem when the eye moves off axis--it's just that the bullet won't hit where the reticle says it will.
There is no defined "point of aim" when the eye is out of line with metallic sights or when the metallic sights are misaligned with each other. The only way to see the point of aim is for the sights to be aligned with each other and with the eye and there's no parallax when that is the case.The parallax error is how far bullet misses point of aim when a parallax situation exists.
In other words, if we're talking about an apparent movement of the "point of aim" on the target due to the motion of the eye, it can't happen with a metallic sight setup because once the eye moves off axis, there is no longer any definable "point of aim". There's just a multiply misaligned system.
Moving the eye off axis in an optical system that is susceptible to parallax creates a parallax situation where the apparent aiming point is not the same as the actual aiming point.
Moving the eye off axis in a metallic sight system effectively "destroys" the aiming point so there is no longer any apparent aiming point at all.
Therefore, it is impossible to call a shot when that happens and the bullet may not hit the 6 foot square target paper 200 yards away. There is no way to tell where the front sight appeared relative to the bullseye when a shot is firedMoving the eye off axis in a metallic sight system effectively "destroys" the aiming point so there is no longer any apparent aiming point at all.
Right?
Bart B. said:Therefore, it is impossible to call a shot when that happens and the bullet may not hit the 6 foot square target paper 200 yards away. There is no way to tell where the front sight appeared relative to the bullseye when a shot is fired
Right?
Calling a shot is a matter of prediction and judgement, not a merely physical phenomenon.
While parallax can be observed when any two objects are at different distances, misalignment of iron sights isn't the same phenomenon as parallax evident in an optic at a given distance. The ideal on an optic is to have everything focused on the same plane. Since that can't ever happen on iron sights, parallax can't be eliminated the same way. On one parallax is a simple alignment problem; on the other its a focal plane issue.
One can remedy or reduce parallax error in an optic with the use of an aperture that demand better alignment, but since greater flexibility and ease of use are part of the advantage of an optic, that's not a very popular remedy.
Both iron and scope sights have parallax problems when aim point on target, sight reference points and aiming eye are not on the same axis. Doesn't matter how far apart they are.Calling a shot is a matter of prediction and judgement, not a merely physical phenomenon.
While parallax can be observed when any two objects are at different distances, misalignment of iron sights isn't the same phenomenon as parallax evident in an optic at a given distance. The ideal on an optic is to have everything focused on the same plane. Since that can't ever happen on iron sights, parallax can't be eliminated the same way. On one parallax is a simple alignment problem; on the other its a focal plane issue.
One can remedy or reduce parallax error in an optic with the use of an aperture that demand better alignment, but since greater flexibility and ease of use are part of the advantage of an optic, that's not a very popular remedy.
I've intentionally misaligned aperture sights to see how far and direction bullets strike from point of aim. I used to think otherwise until my small arms Marksmanship Instructor showed me how to prove otherwise. Easily done if you can shoot your iron sighted rifle sub MOA for 20 shots.
Remember the back end of the barrel moves left if the front sight appears right of aperture center. Both the LOS and LOF pivot on the front sight. That makes the bore point to the right from point of aim on target. Bullet will go that way from point of aim when fired.
Last edited: