Talk:Reflex sight

Parallax free

Not all "red dot" sights are parallax free, as the article claims. The Aimpoint sights are parallax free, and the EO-Tech Holosight claims to be. The Tasco PDP sights do have parallax, as do the C-More, JPoint/Tasco Optima/Firefly and others.--Davidwiz 15:05, 31 October 2006 (UTC)

No sight is truly parallax free, with the possible exception of a laser sight (more on that later). For a sight to be parallax free that means that when the sight is on the target and you move your head around, the reticle does not move. Let's say for a moment the reticle was truly focused at infinity (which is the goal of relfex sights, hence the term "infinity sight" often used for them), then at what range can you hold the sight on the target, move your head, and not have the dot move? The answer is, you can't. At every distance that infinite distance reticle will move exactly as far as the shooter's eye moves. With a normal telescopic sight, if you set the reticle to infinity, this parallax error would be magnified by the optics; with a reflex sight, the error is not magnified. The only reason a laser is parallax free is because the laser stops exactly at the target; if you tried to aim at a spot in the air halfway between the laser and the target, then even the laser wouldn't be parallax free.

Since it's impractical to get the reticle image perfectly parallel, most red dot sights "project" the reticle image to some distance forward. This distance is the distance at which the sight truly is parallax free, and no matter where you move your head, the reticle stays rock steady on the target. At distances less or greater than the parallax free distance, the error will be slight; from muzzle to twice parallax free range the error will be less than or equal to half the objective diameter; beyond that it will increase linearly. This is pretty insignificant when the typical red dot sight uses are considered, so that is why reflex sights are usually described as "parallax free".

Another reason that most red dot sights aren't collimated so that the reticle image is perfectly parallel is that it makes it much harder to focus on the reticle in that case. If the reticle image image is projected to roughly the exptected target range, then it's possible to focus on the reticle and have the target more in focus than if the reticle were at infinity. 66.76.245.3 19:03, 8 September 2006 (UTC)

Reflex sight

Reflex sight redirects here but a Red Dot Sight is a subtype of Reflex sight (one that simply uses a red dot instead of some other type of reticle). We seem to have a set/subset mix up here. There should probably be an article at Reflex sight. 69.72.2.71 (talk) 03:15, 18 December 2007 (UTC)

While technically that is (mostly) true, in practice they're all categorized as red dot sights by most retailers; take a look at the MidwayUSA catalog for example, and you'll find the Bushnell Holosight, basic red dots, and complex sights with multiple reflective reticles combined with rangefinding marks etched in. And the "they're all reflex sights" logic breaks down when you consider the 2x and 4x Trijicon sights, which are red dot sights, but are not reflex sights. Just like the term "tennis shoe" is used to generically refer to any athletic shoe, "red dot sight" in practice covers far more than is technically correct. scot (talk) 14:59, 18 December 2007 (UTC)

What retailer’s use is not actualy the standard here, its reference. Its something where you can use a wp:google test but it runs into the neutrality problems noted there re: if all the hits are retailers; retailers are not a reliable source. This article is currently un-referenced re: neutrality. I have many reflex type sites in hand and none of them are "red dot". That would make Red dot sight on the face of it a sub type using a specific reticle and therefore a sub type of reflex. And "Reflex sight" may have neutrality problems since it may be more correctly called a "Collimator sight", I don't see references in the articles that establish the correct nomenclature.

I would suggest a course of action of removing the redirect at Reflex sight (they are reversible) and put up a properly sourced article there. 69.72.2.71 (talk) 17:34, 18 December 2007 (UTC)

Well, the GunTec dictionary defines a "red dot sight" as "An optical sighting device that forms a red reticle (dot or otherwise) made of light on a glass surface inside a small open-ended box. Red dot sights are often used for short distance firing because they can be easily picked up by the eyes. When the reticle is a dot/circle, it is normally measured in minutes-of-angle."[1] So far that is the only concise definition I've found. Dick Metcalf lumps everything from the original Aimpoint sights to the HOLOsight in to the category of "dot sights", with no mention of "reflex" or "collimator".[2] I think finding a source that says "a reflex/collimator sight is not a red dot sight" is going to be hard; you can find lots of sources that say "a reflex/collimator sight is X" and sources that say "a red dot sight is X", which just supports the case that they can all be considered part of the "red dot sight" class. scot (talk) 22:40, 18 December 2007 (UTC)

I will be looking up more reference when I get the chance, but articles do have to folow logic as well as reference. Red Dot is clearly a sub type (and a fairly recent one at that). I have an "apple pie" ref (you don't need a ref to describe an apple pie), i.e. there are quite a few collimator sites sitting in front of me right now that use beam splitters (reflex?) and other methodes and none of them are "red dot". "Reflex site" its self needs a definition, it may simple be a redirect to a "Collimator site" article. There are tons of collimator type sites out there such as "HUDs" of all types, Telrads, who more specificaly call their sites "reflex", and a few (billion?) non-SLR camera finders. Just Googleing "Collimator site" brings up specific reference that "red dot" comes under "Collimator site"[3]. 69.72.93.208 (talk) 17:04, 21 December 2007 (UTC)

Normally sight/site corrections fall under the job description of grammar nazi, but in this case you are specifically referencing websites about gunsights. i think i could follow your meaning, and i like that you are acting as a voice of reason in the face of an "everybody calls them kleenex" argument. could you please be a little pickier with your website/gunsight spelling usage :)

Longpinkytoes (talk) 12:47, 14 May 2019 (UTC)

Help understanding Red Dots & Reflex Sights

This article is great but it does not really talk about the science behind the sights. This is an important factor. I am looking for info on things like the lenses, the dot (how it gets there), eye relief, parallax free, and magnification. Basically looking for "how it works." I know that the red dot sights with tube designs can have magnifiers, as can AimPoints and EoTechs. Can the tubeless designs have magnifiers as well? How would this work while still being free? There is a 2x magnifying tube red dot, where the magnification only kicks in after a certain distance. So if the target is close up it will not be magnified (so there is still a clear picture/shot) but if it is far away it is magnified. How is this possible? How would that work on a tubeless sight? Thanks, MattTheMan (talk) 04:33, 30 April 2008 (UTC)

Here are some quick and dirty answer to your questions. The way a reflex sight works is by placing a reticle at the focus of a magnifying lens or mirror. By placing the reticle exactly at the focus, the light from the reticle is not only magnified, but it leaves the lens collimated, which means the rays of light are exactly parallel. This gives the illusion that the reticle moves with respect to the body of the sight, as your head moves, in effect "projecting" the reticle out to infinity, or, if focused slightly differently, to any range the manufacturer chooses. I'll see if I can get a diagram put together and into the article later.

As to magnification, to provide a focused, magnified image requires more than just a single lens, just like a telescope is a collection of multiple lenses. So to make a magnifying dot sight, you need to have a tube with more than one lens in it. The reticle in a standard telescopic sight is placed on a focal plane, just like the reticle in a red dot, but with a telescopic sight, you've got two focal planes to work with; the front focal plane and the rear focal plane. Either one will work; the front focal plane will give you a reticle that gets larger and smaller as you zoom the image in a variable power scope, and the rear focal plane will give you a reticle that remains constant in size during zooming. In both cases, the reticle is "projected" out to a given distance, either a fixed range chosen by the manufacturer (usually between 50 and 200 yards) or user selectable via an adjustable objective (AO).

As for "the magnification only kicks in after a certain distance", I'm not sure I buy that; I suspect that it's a standard 1x-2x zoom scope with a dot reticle. The problem with the non 1x scopes is that they're not really reflex scopes--to keep the reticle centered on the 2x zoom image, it must move twice as far when you move your head as a reflex sight, which means the reticle image is divergent, not collimated. scot (talk) 14:00, 30 April 2008 (UTC)

Actually scratch that last bit about a divergent image from the telescopic sight; I think the image is (mostly) collimated by the eyepiece lens, putting the virtual image out at the parallax distance for the scope. However, the reticle image is still magnified, and moves at a higher rate than the observer. scot (talk) 19:34, 30 April 2008 (UTC)

Hi thanks for the speedy response. The 2x red dot I was talking about is this. There is a review here where, under the "Target Practice" section, it talks about the magnification being noticeable at 30ft. My description of "kicking in" was inaccurate. Anyway, the reason I posted here was to find a little about how the insides work, because I am in the market for a red dot sight but I think magnification would be useful to get that extra little edge. I like the idea of magnification, but I do not like tubed designs. I was hoping for something of this type of tubeless design but with some sort of magnifying add on or something. Basically I am looking for all the pros of a tubeless red dot sight (parallax free, unlimited eye relief, keep both eyes open, does not obstruct view) with the pros of magnification. Is this even possible or no? MattTheMan (talk) 05:35, 1 May 2008 (UTC)

In short, no, you can't get the unlimited eye relief and open tube with magnification. Probably not "parallax free", either, though in reality there is no such thing as a parallax free optical sight. Parallax just means that as you move your head, the target and the reticle don't move relative to each other; the target must be at the same distance as the virtual image to make this happen. Since ideally a red dot projects to infinity, it is only parallax free with respect to targets set at an infinite distance. In other words, a red dot sight is the worst possible case, NEVER free from parallax; magnifying scopes are at least parallax free at one distance. Laser sights truly are parallax free, as they actually bounce light off the target, and so the "reticle" and the target will always be at the same distance, but they're only useful in low light, and since they normally mount below the barrel, you've already lost fully half of your maximum point blank range.

I've got some specific recommendations for you, but as that's outside the Talk page scope, I'll head to your user page... scot (talk) 13:46, 1 May 2008 (UTC)

Red Dot Sight Talk Page

• I fully intended to move the RDS talk page over to this "new" entry, but apparently screwed up the process. There wasn't much on it, but I didn't want anyone to think I was trying to deep-six those discussions intentionally. --Skidoo (talk) 15:29, 25 February 2009 (UTC)

Merger and scope

The scope of this article is too narrow, I guess because it is a convert from "Red Dot Sight". Reflex sights - some sort of beam splitter/mirror reflecting a collimated reticle at infinity into the observers eye covers everything from camera viewfinders to HUDs. The article needs the following cleanups:

• This article and Reflector sight need to be merged in some way. The terms are synonymous[4] with "reflector sight"[5] google testing slightly ahead of "reflex sight"[6]. Merger could go either way.
• The firearm material in this article should become a sub heading, not the prime focus.
• The firearm material is a bit too detailed straying into WP:NOTTEXTBOOK, uses un-cited weasel words such as "preferred" and "many", and the more general descriptions cover all types of reflex sights.
• The lead of this article is buried, the text under "Operation" (with some modification) is the real lead description/definition per WP:MOSBEGIN- i.e.:

"A reflex sight is a sight that combines refractive and reflective elements to presents the observer with a image such as a reticle superimposed over a distant "target". They work by using an optical collimator to create a collimated image of a luminous or reflective overlay image or reticle, and reflect that image off a dichroic mirror or beam splitter to allow the observer to see the image superimposed in the sight's field of view in focus with no parallax from close range up to infinity".

• The description of an "occluded" sight seems to be another type of sight , a “Collimator sight” per Elementary optics and application to fire control instruments By United States. Dept. of the Army.

“Elementary optics and application to fire control instruments By United States. Dept. of the Army” also gives a good overview definition of a Reflex Sight. Fountains of Bryn Mawr (talk) 15:27, 16 February 2010 (UTC)

History

Since Call of Duty will soon have convinced children worldwide that reflex sights have been widely used since World War 2, it would be great to have some history about reflex sights, when they were first invented and a chronology of their use, etc. 68.127.36.191 (talk) 04:06, 22 October 2010 (UTC)

there also seems to be a huge disconnect between avid gun consumers, and uninitiated knowledge seekers (see above discussion about the use of commercial websites as sources of technological canon). the idea that a reflex sight is most useful when the target (ie. ducks, airplanes) can suddenly move so far that tracking the gun to the target requires uncoupling the sight/scope from the user's eye seems to take a few hours of search hits to uncover. also that the earliest widespread military application of the technology was in hydraulic turrets where it would be far too hazardous for anything to be close to the gunner's head.

Longpinkytoes (talk) 13:16, 14 May 2019 (UTC)