Ideal Optic Distance From Eye [Explained With Pictures]

scar17 with Trijicon ACOG with RMR piggyback setup

You got a rifle and an optic! now the question is where do you mount the optic while there is so much rail space available?

In this guide, we're going to show you the ideal optic distance from eye when using a magnified optic or a reflex sight, and why.

Check it out.

Ideal Optic Distance From Eye [Pictures]

Mount A Red Dot Or HWS Closer To The Eye

X95 with aimpoint micro and MODLITE

Mounting a reflex sight closer to the eye allows the shooter:

  • Acquire the sight picture faster and have a bigger field of view.
  • Avoid optic lens frame getting in the way
  • More flexible cheek positions and still able to see the reticle
  • Much better for cross-eye dominance shooters
Eotech in action

Better FOV & Speed - Bring it right in front of your eye & shoot! Using a large field of optics like the EOTech EXPS3, Holosun 510C, and other large window lenses, so the shooter can aim with two eyes open focus on the target while the reticle just superimposes over the target.

When To Back Off A Little? - Just make sure you don't place the optic too close to the point where the frame of the optic is obstructing your situational awareness.

X95 where to mount optic

Moving the sight closer to the eye and aim with two eyes open also helps cross eye dominant shooters to have better sight picture acuity when using a parallax free optic.

Mount The Optic More Forward

arsenal ak with sig romeo4 red dot sight

When rail space is limited or not available on the rifle, the shooter can mount the optic more forward on the rifle.

It's just like an AK with a top rail handguard optic mount. When the shooter mounts the sight closer to the muzzle, the shooter can drive the gun faster to the target and also acquire sight pictures fairly quickly.

Other times, mounting a lightweight red dot more forward allows for more rail space to mount a night vision scope or reflex magnifier optic, and it doesn't significantly shift the rifle's center of gravity.

Check out other optic mounting locations for an AR rifle here

Where To Mount Optic For The Best Eye Relief

rifle scope lens and aiming reticle

As a rule of thumb, keeping 3 - 4" eye relief distance when using a magnified optic to get a good sight picture without the scope shadow and a good cheek weld position.

Minot AFB security forces M4 with ACOG 4X scope

Referenced USAF Minot AFB 5th Security Forces

Most magnified scopes on the market today have about 3-4" eye relief distance, so the shooter can comfortably get behind the rifle to prevent scope bite when shooting a heavy recoil rifle, and it provides enough head clearance for shooters wearing tactical helmets without bumping into the ocular lens.

Common FAQ

Is There Eye Relief Distance For A 1X Prism Sight?

A 1X prism sight has a shorter eye relief (Typically 3 - 4"). Typically A 1X prism sight feels like a 1X red dot, but it's a scope with a detailed glass etched reticle that never dies even if the battery does.

Learn about red dot VS prism sight here

Does Optic Distance To Eye Affect Reticle Parallax?


Optic distance to the eye doesn't affect reticle parallax unless the head position shifts significantly in relation to the target plane.

Does Optic Distance To Eye Fix Astigmatism?

Optic distance from eye does not have anything to do with astigmatism.

shooters with astigmatism see this

Astigmatism has to do with the imperfection in the curvature of your eye and light refraction that causes blurred reticle and sight picture.

Putting the optic closer or further doesn't have any effect on reticle clarity if the shooter has astigmatism.

Try a prism sight or a red dot reticle size between 3 and 8 MOA.

Check out optics best for shooters with astigmatism 

Ying Xu

US Air Force veteran nuclear weapon officer. Aerospace engineering bachelor's degree from the University of Kansas. Experienced as a certified NRA range safety officer. Working as a search engine expert for