Editing Reticle (section)

===Reticle focal plane===
The reticle may be located at the front or rear focal plane (First Focal Plane (FFP) or Second Focal Plane (SFP))<ref>{{cite web|url=https://accurateordnance.com/first-vs-second-focal-plane/ |title=First vs Second Focal Plane – What is the Differences?|date=25 July 2022 }}</ref> of the telescopic sight. On fixed power telescopic sights there is no significant difference, but on variable power telescopic sights the front plane reticle remains at a constant size compared to the target, while rear plane reticles remain a constant size to the user as the target image grows and shrinks. Front focal plane reticles are slightly more durable, but most American users prefer that the reticle remains constant as the image changes size, so nearly all modern American variable power telescopic sights are rear focal plane designs.{{citation needed|date=May 2019}} American and European high end optics manufacturers often leave the customer the choice between a FFP or SFP mounted reticle.

====Collimated reticles====
[[File:Reflector reflex sight diagram 3.png|thumb|right|Diagram of three types of reflector sights that produce collimated reticles. The top uses a collimating lens (CL) and a beam splitter (B) to create a [[virtual image]] at infinity (V) of a reticle (R). The bottom two use half silvered curved mirrors (CM) as the collimating optics with the reticle off-set or between the mirror and the observer.]]
{{main|Reflector sight}}
Collimated reticles are produced by non-magnifying optical devices such as [[reflector sight]]s (often called ''reflex sights'') that give the viewer an image of the reticle superimposed over the field of view, and blind [[collimator sight]]s that are used with both eyes. Collimated reticles are created using [[refraction|refractive]] or [[reflection (physics)|reflective]] [[Collimator#Optical collimators|optical collimators]] to generate a [[Collimated light|collimated]] image of an illuminated or reflective reticle. These types of sights are used on surveying/triangulating equipment, to aid celestial telescope aiming, and as [[gunsights|sight]]s on [[firearm]]s.  Historically they were used on larger military weapon systems that could supply an electrical source to illuminate them and where the operator needed a wide field of view to track and range a moving target visually (i.e. weapons from the pre [[laser]]/[[radar]]/[[computer]] era). More recently sights using low power consumption durable [[light emitting diode]]s as the reticle (called ''[[red dot sight]]''s) have become common on small arms with versions like the [[Aimpoint CompM2]] being widely fielded by the U.S. Military.

====Holographic reticles====
[[Holographic weapon sight]]s use a [[hologram|holographic]] image of a reticle at finite set range built into the viewing window and a [[collimated light|collimated]] [[laser diode]] to illuminate it.  An advantage to holographic sights is that they eliminate a type of [[parallax]] problem found in some optical collimator based sights (such as the [[red dot sight]]) where the spherical mirror used induces [[spherical aberration]] that can cause the reticle to skew off the sight's [[optical axis]]. The use of a hologram also eliminates the need for image dimming narrow band reflective coatings and allows for reticles of almost any shape or [[milliradian|mil]] size. A downside to the holographic weapon sight can be the weight and shorter battery life. As with red dot sights, holographic weapon sights have also become common on small arms with versions like the [[EOTech|Eotech]] 512.A65 and similar models fielded by the U.S. Military<ref>{{cite web |url=http://www.defenseindustrydaily.com/Holographic-Sights-for-SOCOM-M4s-06416/ |title=Holographic Sights for SOCOM M4s |access-date=30 August 2012}}</ref>  and various law enforcement agencies.