Page MenuHomeFeedback Tracker

MRCO co-witnesses BUIS
Closed, ResolvedPublic


The MRCO (IOR 1.1-4x scope) cowitnesses the back-up iron sights (BUIS), at both minimal zoom and maximal zoom. This should not be possible. The lowest magnification of this particular scope in actually not 1x, but 1.1x, making the BUIS out of focus.

Even scopes that have true 1x, (called flash-dot scopes) like the Schmidt&Bender PM II Short Dot are *not parallax free* like a red dot or holographic optic. The 1x zoom setting would typically set parallax around 100m, meaning that even if the scope has a true 1x setting, the BUIS (and the rest of the rifle) would be out of focus and blurry.

More in detail, the BUIS would appear to be almost transparent.

Further information can be found in this excellent forum post by a professional armourer: {F20318} {F20319}


Legacy ID
Steps To Reproduce

Spawn Independent marksman, look through scope both zoomed out and zoomed in. Note the co-witness of the BUIS. Also note that the gun chassis is sharp.

Event Timeline

p00d73 edited Steps To Reproduce. (Show Details)Jun 26 2013, 3:12 AM
p00d73 edited Additional Information. (Show Details)
p00d73 set Category to Visual-Weapons.
p00d73 set Reproducibility to Always.
p00d73 set Severity to None.
p00d73 set Resolution to Open.
p00d73 set Legacy ID to 3014507439.May 7 2016, 2:56 PM
Bohemia added a subscriber: p00d73.Jun 26 2013, 3:12 AM

sooo..... the only real X1.0 its the iron sight?

It's not really about being true x1, but being parallax free. The way a variable power scope works prevents it from being parallax free, even if it is a true 1x (which are rare).

Huron added a subscriber: Huron.May 7 2016, 2:56 PM
Huron added a comment.Jul 5 2013, 9:53 PM

This is untrue, the front sight would not appear blurry in 1x mode. Parallax is to do with the appearance of the reticle depending on the viewing plane. A parallax free optic uses projection methods to make the reticle move as little as possible in relation to the target when being viewed through the optic off-center. The issue 1x-Nx optics have is that in 1x mode is that the user must look directly through the optic as they would with a magnifying optic, otherwise they will experience scope shadow and a potentially misaligned reticle.


Parallax free and depth of field have nothing to do with each other. Neither is the sight "co witnessed" with the Ironsights.

The engine cannot do DOF blur very well, and to co-witness a sight with the ironsights mean that point of aim, point of impact is identical when looking through either optics or irons.

p00d73 added a comment.Jul 6 2013, 1:42 PM

InstaGoat: no. Co-witness in general only refers to the ability to use the BUIS through the optic. Absolute co-witness is what you describe, where the reticle of the optics rests on top of the BUIS when you use either one. A 1/3 co-witness is the one used in ArmA 3, where the BUIS are below the typical line of aim.

MadDogX added a subscriber: MadDogX.May 7 2016, 2:56 PM

Mass closing ancient tickets with no activity for > 12 months; assume fixed or too trivial.

If this issue is still relevant in current dev build, please re-post.