Scope Eye Relief Adjustment

[Fred Bohl]

I've been mounting scopes and teaching others how to mount scopes for 71 years. My own health and my wife's are severely limiting my activities so I'm putting together a notebook for others to use. Today I'm asking for comments on this page I've compiled on scope eye relief adjustment:



Does this adequately describe the difference in appearance for different eye positions?

 

[WileyG]

I believe you've provided images that accurately depict each scenario. A full tube of visibility at a position where the weapon is shouldered and comes to rest in a position that comes naturally to the shooter, without having to lean ones head into or away from the scope, is the desired outcome.

 

[Fred Bohl]

A full tube of visibility at a position where the weapon is shouldered and comes to rest in a position that comes naturally to the shooter, without having to lean ones head into or away from the scope, is the desired outcome.

You have described the positioning as I've been teaching it for 71 years. In recent years however, I modified my version to suggest that the shooter find the sweet spot position with the scope at the power to be used for aiming. As the range of magnification for modern scopes has increased to as much as 10 to 1, the eye relief changes enough to be noticeable within that range.

 

[Eagle Six]

Fred I understand what you are saying. However, the field of view never changes, it is fixed and only changes when we make a power adjustment. What will change with improper eye relief is how much of the field of view we can see without shifting our eye position. During application if we have to shift our eye sideways or up and down to see the extreme edges of field of view, then we could say the field of view is narrower. I think if you have a short note explaining that field of view does not change, rather some of the field is obscured. This may seem nitpicking.

 

[WileyG]

When I get ready to mount a scope I have it in the rings with screws loose enough for me to slide the scope. I get it approximately where I want it and begin a series of shouldering the weapon with my eyes closed until I have my cheek weld and feel comfortable. Then I open my eyes, check the view and move the scope as necessary. I do this multiple times until it's repeatable without moving the scope any more. Then the weapon goes gently into my rifle cleaning station/vice. I snug one ring and mark the tube at the edge of that ring with a #2 pencil. Then I loosen that ring and begin the process of leveling/plumbing the reticle.

 

[Fred Bohl]

However, the field of view never changes, it is fixed and only changes when we make a power adjustment.

For my purposes, I don't want to lead into a discussion of Real FOV vs Apparent FOV vs Power FOV on this page of notes.

What will change with improper eye relief is how much of the field of view we can see without shifting our eye position.

How about my changing 'field of view will be narrower' to 'visible field of view will be reduced' for both too short and too long eye relief?

 

[Eagle Six]

How about my changing 'field of view will be narrower' to 'visible field of view will be reduced' for both too short and too long eye relief?

I think that would be accurate and understandable.

 

[Fred Bohl]

Updated page:

 

[Eagle Six]

I like it.

 

[Turbulent Turtle]

It's almost as if there was a Goldilocks zone.

 

[Ackman]

When I get ready to mount a scope I have it in the rings with screws loose enough for me to slide the scope. I get it approximately where I want it and begin a series of shouldering the weapon with my eyes closed until I have my cheek weld and feel comfortable. Then I open my eyes, check the view and move the scope as necessary. I do this multiple times until it's repeatable without moving the scope any more. Then the weapon goes gently into my rifle cleaning station/vice. I snug one ring and mark the tube at the edge of that ring with a #2 pencil. Then I loosen that ring and begin the process of leveling/plumbing the reticle.

I do this first with rings mounted and no scope to check ring height. Front ring centered in back ring is correct height. Not every stock is the same.

 

[Fred Bohl]

It's almost as if there was a Goldilocks zone.

Back in the day, and for some manufacturers even today, their specifications would show the eye relief values for the 95% points.

The graphics and photographs used in my earlier posts are at about 77% to better illustrate the effect.