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Cross hairs moving

Printed From: OpticsTalk by SWFA, Inc.
Category: Scopes
Forum Name: Rifle Scopes
Forum Description: Centerfire long gun scopes
URL: http://www.opticstalk.com/forum_posts.asp?TID=44083
Printed Date: December/19/2018 at 01:56


Topic: Cross hairs moving
Posted By: RickCunn
Subject: Cross hairs moving
Date Posted: April/19/2017 at 19:53
I have a Burris Model 200335 Fullfield E1 4.5x14x-42 mm Ballistic Plex E' Reticle mounted on a Mossberg MVP.  I have been shooting at 100 yards.  The parallax is set to 100 yards.  The rifle is on a bench on a solid foundation. I have my eye within the eye relief.  I set the cross hairs on the target center.  If I shift my eye left or right the cross hairs move fairly significantly right or left.  In the vertical direction there is very little change in the cross hair position when I move my eye vertically.  Of course, that makes hitting the target difficult.  Is the problem with me or the scope?  



Replies:
Posted By: Kickboxer
Date Posted: April/23/2017 at 09:53
Originally posted by RickCunn RickCunn wrote:

I have a Burris Model 200335 Fullfield E1 4.5x14x-42 mm Ballistic Plex E' Reticle mounted on a Mossberg MVP.  I have been shooting at 100 yards.  The parallax is set to 100 yards.  The rifle is on a bench on a solid foundation. I have my eye within the eye relief.  I set the cross hairs on the target center.  If I shift my eye left or right the cross hairs move fairly significantly right or left.  In the vertical direction there is very little change in the cross hair position when I move my eye vertically.  Of course, that makes hitting the target difficult.  Is the problem with me or the scope?  

Rick, read this over a couple of times.  I think it will help.

http://www.opticstalk.com/what-exactly-is-parallax-anyway_topic5026.html - http://www.opticstalk.com/what-exactly-is-parallax-anyway_topic5026.html


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Opinion,untempered by fact,is ignorance.

There are some who do not fear death... for they are more afraid of not really living


Posted By: Rancid Coolaid
Date Posted: April/23/2017 at 10:15
Be aware that the markings on a parallax knob are approximations, not calibrated. Just because the knob has a 100 setting does not mean the scope is calibrated to be parallax-free at 100.

The same is true of most scope's power ring also, but that is a topic for another time.

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Freedom is something you take.
Respect is something you earn.
Equality is something you whine about not being given.


Posted By: koshkin
Date Posted: April/23/2017 at 14:30
Did you carefully adjust the eyepiece for your eye?



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The greatest obstacle to discovery is the illusion of knowledge


Posted By: RickCunn
Date Posted: May/02/2017 at 22:11
Kickboxer's link helped, especially the LBL piece by Bercovitz.  I am a numbers guy, so his image distance examples clarified Rancid Coolaid's comment that the parallax markings (on the bell, no knob in this scope) are approximate.  And interestingly on this scope, at 50 yards the parallax is very small with the bell adjustment set at 50.  At 100 yards and the bell adjustment set to 100 the parallax seems to be more sensitive.  Which is explained by Bercovic's examples.  I believe that the solution is to futz with my bell at 100 yards.  

I think my eyepiece is well focused on the crosshairs.  However, I like Chris Farris' suggestion to do it with Kleenex to provide a diffuse white background.  Nothing worthwhile on TV tonight anyway.

BTW, I recall reading somewhere that one should not stare continually at the crosshairs while focusing the eyepiece, something to do with the eye trying to interpret what it sees.  The recommendation was to look away, adjust the eyepiece, and then quickly check the focus.  Repeat this until the focus is attained.  Am I recalling correctly?

I liked Chris Farris description of the stuff inside a scope.  A diagram would surely be helpful.  


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Man is not free unless government is limited - RR


Posted By: Kickboxer
Date Posted: May/03/2017 at 06:12
Glad I could steer you to some help.  Parallax is a hard master...

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Opinion,untempered by fact,is ignorance.

There are some who do not fear death... for they are more afraid of not really living


Posted By: Rancid Coolaid
Date Posted: May/03/2017 at 07:10
And you are recalling correctly: if you stare at the crosshairs, your eye will adjust focus. Using the "look at it then look away" will allow the reticle to be focused for good.
If you find yourself adjusting focus with any regularity, you are doing something wrong. It should be a "one and done" deal.

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Freedom is something you take.
Respect is something you earn.
Equality is something you whine about not being given.


Posted By: RickCunn
Date Posted: May/03/2017 at 17:16
Problem resolved.  Today at the range the parallax problem at 100 yards resolved with the parallax adjustment on the bell set to a bit past 100 yards.  

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Man is not free unless government is limited - RR


Posted By: Kickboxer
Date Posted: May/04/2017 at 06:25
Great to  hear.  Welcome to OT...

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Opinion,untempered by fact,is ignorance.

There are some who do not fear death... for they are more afraid of not really living


Posted By: RickCunn
Date Posted: May/04/2017 at 16:46
I may have been a bit premature on the parallax.  I noticed today at 100 yards today that when I shift my eyes vertically there is essentially no movement of the target relative to the crosshairs.  That is not the case with horizontal movement.  If I shift my head slightly left-right I do see a lot more movement of the target relative to the crosshairs, as compared to the vertical movement.  That seems very odd to me, that the parallax would not be the same in the two axes.  What am I missing here?  

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Man is not free unless government is limited - RR


Posted By: Kickboxer
Date Posted: May/05/2017 at 06:21

another good read...

https://gunsmagazine.com/parallax-and-distortion/ - https://gunsmagazine.com/parallax-and-distortion/

Reemphasizing: a good cheekrest can eliminate parallax... practice and consistency...



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Opinion,untempered by fact,is ignorance.

There are some who do not fear death... for they are more afraid of not really living


Posted By: RickCunn
Date Posted: May/05/2017 at 10:45
Thanks for that.  I spoke to Burris and they told me it is possible to have no parallax in one axis with some small parallax in the other axis.  Before I send it back I will spend a little more time futzing with the whole setup, and shoot some more.  I suspect the problem is with my inexperience.  

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Man is not free unless government is limited - RR



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