Parallax.... how to?

Crews

Sergeant
May 11, 2017
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#1
So I get the concept behind parallax..... if you're looking at the speedometer from the passenger seat the needle looks like it's in a different spot that what it is from directly in front of it in the driver's seat. And I hear folks talking about how this may make your reticle tell you you're aiming at stuff that you're not. What I don't really understand is how to make sure I'm not DOING it.

How do you figure out if you are making an aiming error due to parallax issues? I've got an ATACR, and played with the adjustment when I'm shooting out at distance... often times there isn't a real huge discernible difference in the reticle clarity from one end of the adjustment to the other. I can see clearly and hit the plate, and I figure if there's a discrepancy in my POI it's probably just me needing to work harder on my fundamentals and trigger control. Is it as easy as turning the knob until the target is in the best focus for my eyeballs and rolling with it? Is there something in my sight picture that I should be looking out for that indicates there is an error?
 

Sheldon N

Blind Squirrel Finds a Nut
Sep 24, 2014
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#2
Is it as easy as turning the knob until the target is in the best focus for my eyeballs and rolling with it? Is there something in my sight picture that I should be looking out for that indicates there is an error?
Generally dialing for focus works.

If you want to test for perfect parallax, place the rifle in a position where it has the crosshairs on target and is stable without you holding or touching it. Then hovering over the cheek piece look through the scope (again not touching the rifle) and move your eye around. If you can see the reticle move around on the target then you have parallax error.

It's more sensitive and prone to error at closer distances. Out far it's not nearly as much of an issue.
 
Likes: 47guy
Jul 15, 2017
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reno,nevada
#4
Generally dialing for focus works.

If you want to test for perfect parallax, place the rifle in a position where it has the crosshairs on target and is stable without you holding or touching it. Then hovering over the cheek piece look through the scope (again not touching the rifle) and move your eye around. If you can see the reticle move around on the target then you have parallax error.

It's more sensitive and prone to error at closer distances. Out far it's not nearly as much of an issue.
This right here.^^^
 

308pirate

Gunny Sergeant
Apr 25, 2017
4,663
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#5
often times there isn't a real huge discernible difference in the reticle clarity from one end of the adjustment to the other.
That's because parallax adjustment has nothing to do with reticle FOCUS (clarity and focus are not the same thing). Parallax adjustment has everything to do with bringing the target image into focus (technically bringing the target into the same focal plane as the reticle).

Reticle is focused to your particular eye using the occular's diopter adjustment. The target is focused using the parallax knob. Rough adjustment by watching the target come into focus, fine adjustment as Sheldon N described.
 
Likes: Infidel01

Crews

Sergeant
May 11, 2017
481
92
28
#6
Okay, thanks for the input guys. The take away for me is to first go focus the reticle for me using the diopter adjustment. Then make sure I’m at least getting the best focus I can with the knob. If I want to verify leave the rifle stationary and move my head a little bit to see if the reticle moves around.
 

Racer88

New Hide Member
Nov 10, 2018
48
21
8
#7
I get the concept of parallax. I also understand adjusting the diopter is to get the reticle in focus, parallax knob focuses the target image. I'm also familiar with the technique of moving your head slightly to see if there is any movement of the reticle relative to the target to confirm parallax-free.

Here's my question: I find that the distance markings on the parallax know rarely / never coincide with the measured target distance when ideally focused. Especially at the longer distances... say 300+ yards... once I have the target sharply focused, the knob is closer to the "infinity" end, past the indicated distance number on the knob.

Can I safely assume that the distance markings on the parallax knob effectively mean nothing? Pay no attention to them?

Thanks!
 

KML7201

New Member
Oct 15, 2018
38
33
18
NY
#8
I get the concept of parallax. I also understand adjusting the diopter is to get the reticle in focus, parallax knob focuses the target image. I'm also familiar with the technique of moving your head slightly to see if there is any movement of the reticle relative to the target to confirm parallax-free.

Here's my question: I find that the distance markings on the parallax know rarely / never coincide with the measured target distance when ideally focused. Especially at the longer distances... say 300+ yards... once I have the target sharply focused, the knob is closer to the "infinity" end, past the indicated distance number on the knob.

Can I safely assume that the distance markings on the parallax knob effectively mean nothing? Pay no attention to them?

Thanks!
Yes, ignore the markings. Just turn the knob to focus the target.
 
Likes: Racer88
Jan 31, 2018
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#9
I get the concept of parallax. I also understand adjusting the diopter is to get the reticle in focus, parallax knob focuses the target image. I'm also familiar with the technique of moving your head slightly to see if there is any movement of the reticle relative to the target to confirm parallax-free.

Here's my question: I find that the distance markings on the parallax know rarely / never coincide with the measured target distance when ideally focused. Especially at the longer distances... say 300+ yards... once I have the target sharply focused, the knob is closer to the "infinity" end, past the indicated distance number on the knob.

Can I safely assume that the distance markings on the parallax knob effectively mean nothing? Pay no attention to them?

Thanks!
If the markings on your particular optic don’t line up, just learn where the line up for common distances. This helps a bit to set before you shoot a stage.

Sometimes the markings are close and sometimes not. This is why some brands such as TT do not out distance markings on their parallax knob.
 

perttime

Registered from Finland
Nov 28, 2018
63
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Finland
#10
...
It's more sensitive and prone to error at closer distances. Out far it's not nearly as much of an issue.
I believe people who do Airgun Field Target competition use parallax to estimate distance to target. Distances are very short by centerfire rifle standards, so parallax errors are not hard to see. Turn your focus/parallax wheel until there is no error, note the indicated distance, and set your elevation knob accordingly.
 
Feb 10, 2017
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#11
Okay, thanks for the input guys. The take away for me is to first go focus the reticle for me using the diopter adjustment. Then make sure I’m at least getting the best focus I can with the knob. If I want to verify leave the rifle stationary and move my head a little bit to see if the reticle moves around.
One other thing. If you have a FFP reticle, focus the diopter with the parallax on the infinity setting. Some people forget this step.
 
Likes: Diver160651
Feb 7, 2013
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The West
#13
Like a lot of guys in here I have had way to many nice scopes and brands to list. Of all my scopes, the ATCAR 5-25 (a great scope) had one of the worst yardage markings of those that had them. Hence NF argument against them for years.

Some scopes seem more prone to conditions messing with the actual location required for the knob.
 
Sep 16, 2009
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#15
To further confuse you, the point of maximum optical clarity does not always coincide with minimum parallax.
To field check simply move your head with rifle on bipod or tight sling etc.
Some scopes will adjust for clarity but parallax does not change.