Red Dot Sight

A  is a type of gun sight (a type of reflector or "reflex" sight) that specifically uses a red light emitting diode (LED) at the focus of a curved mirror, producing a red spot reticle as a precise aiming point. In gameplay, it is depicted as a "tubed sight", all the optics are contained in a tube, or what is called an "open sight", no tube, just the optical window sticking up similar to a miniature Heads Up Display. It appears as an attachment in Call of Duty 4: Modern Warfare, Call of Duty: Modern Warfare 2, Call of Duty: Black Ops, Call of Duty: Modern Warfare 3 and Call of Duty: Modern Warfare 3: Defiance. Some versions of the game have a Reflex Sight, a depiction of an early Red Dot Sight.

Call of Duty 4: Modern Warfare
"Replace the iron sights with a precision reflex sight."

- Attachment description

Campaign
In the campaign, Red Dot Sights seen are on the G36C, the standard M4A1, the silenced M4A1 SOPMOD, and the P90-SD. There are two types of Red Dot Sights: the tube-like Red Dot unique to the M4A1 and G36C, and the open Multiplayer type, available on the M4A1 SOPMOD and P90-SD.

Multiplayer
In Call of Duty 4: Modern Warfare, the Red Dot Sight is available for all weapons except sniper rifles, pistols, and the MP44 assault rifle. When selected as a weapon attachment, the red dot sight replaces the weapon's iron sights. In multiplayer, the Red Dot Sight is obtained by completing the first marksman challenge of any Assault Rifle, Submachine Gun, Light Machine Gun, or Shotgun. The Red Dot Sight is popular because it allows full peripheral vision and is clearer and easier to use than iron sights. However, the Red Dot Sight does not actually increase the weapon's accuracy.

AK-47 changes
The Red Dot Sight has an adverse effect on the AK-47 whereby it reduces the minimum damage from 30 to 20, meaning that with the Red Dot sight enabled, the AK-47 will require one more bullet to kill at longer ranges. This effect also happens if the Silencer is equipped.

Call of Duty: Modern Warfare 2
In Call of Duty: Modern Warfare 2, the Red Dot Sight has some changes. The new model is square, smaller, less obtrusive, and allows for a better peripheral view. For the most part, it is similar to the Red Dot Sight in Call of Duty 4. Some weapons now have their own unique Red Dot Sights; the TAR-21 uses the MARS Sight and the F2000 also uses its own unique red dot sight. All Red Dot Sights, except for the F2000's, are disabled when an EMP is deployed. Getting 60 kills while aiming down the Red Dot Sight unlocks the Holographic Sight for primary weapons.

The key difference between the Holographic Sight and the Red Dot Sight is that the Red Dot is smaller which allows for better accuracy at range whereas the Holographic sits higher on the weapon and reduces the effects of the muzzle flash when a player is aiming down their sights. Some people find it easier to see their target and quickly find the reticle due to the translucent "cut-out" cross-hair which is a small circle with a larger circle around it. Others find that the larger sight actually obscures the target making it hard to aim precisely and acquire targets at range. The larger circle is much closer to the smaller circle, which is why the larger one obscures the target so much. It has a thicker frame than the Red Dot Sight, again reducing visibility. The preference between this sight and Red Dot Sight depends on whether the player needs long range pinpoint accuracy and has time for the sway to settle or whether the player will be firing on the move. It is also important to note that on the sunny maps (such as Afghan), the Holographic sight will sometimes appear to glare, making far shots difficult, especially against snipers who are difficult to see.

Due to the height of the Holographic Sight and its positioning, many will choose the type of sight depending on the sight on the gun. For example, for the UMP .45, where the sight is lower down (see image) many will choose a Holographic Sight over a Red Dot Sight, as the Holographic Sight doesn't block as much of the screen as it normally would. However, on weapons such as the AK-47 where the sight sits on top, many players will choose the Red Dot Sight instead, as the Holographic Sight will take up more space and obstruct the player's peripheral view.

TAR-21 Variant
The MARS Sight, also referred to as the "TAR-21 Red Dot Sight", has a difference appearance as it looks somewhat similar to a Holographic Sight, but otherwise works the same as a regular RDS. The MARS Sight is only found in Multiplayer, whereas in the Singleplayer Campaign and in Special Ops the TAR-21s are found with the standard RDS.

F2000 Variant
Also referred to as the "F2000 Scope" or the "F2000 Red Dot Sight", it is the replacement for the standard RDS on the F2000. It is similar in appearance to the Call of Duty 4 campaign's M4A1 (not including the M4A1 SOPMOD) and G36C tube-like Red Dot Sight, though the F2000's is thicker and longer. The sight is blurry, and somewhat difficult to use at range because of this. Interestingly, it is not disabled during an EMP. In the Campaign missions "No Russian" and "Loose Ends" an F2000 with a regular Red Dot Sight can be found.

Call of Duty: Black Ops
The Red Dot Sight returns in Black Ops, seen mounted on the Commando in the multiplayer teaser trailer. Unlike the Red Dot seen in previous games, this one has a different design, being rounder and more flush with the weapon. The AK-47 and its derivatives in-game, the AK-74u and RPK, use the Kobra EKP-1S-03M red dot that was designed for the AK frame. The player can customize the color and shape of the reticle along with the lens color. There are 7 reticle colors and 6 lens colors. There, also, are many different reticles to choose from.

Customization
Each custom shape costs. Including the default dot, there are 40 different shapes. The color of the reticle can also be changed for, with the possible lens colors being green, blue, purple, teal, yellow, red and orange. On the Wii version, red dot sight and reflex sight can't be customized.

Call of Duty: Modern Warfare 3
The Red Dot Sight once again reappears in Modern Warfare 3. It was first seen mounted on a silenced MP5 in the E3 reveal for Modern Warfare 3. It looks identical to the Call of Duty 4: Modern Warfare variant. It was also spotted on an enemy AK-74u during the E3 reveal, and on an AK-47 in the mission "Black Tuesday".

In multiplayer, Assault Rifles, SMGs, and LMGs unlock the Red Dot Sight at Weapon Level 2. Shotguns unlock it at Weapon Level 12, and Machine Pistols unlock it at Weapon Level 7. The Red Dot Sight will give a 1.35x zoom when aiming through it.

Survival Mode
The Red Dot Sight is available as weapon upgrade in Survival Mode at level 7 and costs $750. It can be purchased from the Weapon Armory. It is cheaper than the Holographic Sight while serving the same purpose.

Behind the Scenes
During the Survival trailer, it appeared that there were two types of Red Dot Sights; one similar to the Call of Duty 4: Modern Warfare version and one similar to the Call of Duty: Modern Warfare 2 version. In the final game, however, only the Call of Duty 4 variant appears. In the Special Ops mission "Kill Switch" however, it is possible to find an    AK-47 with a Modern Warfare 2 Red Dot Sight with Digital Camo.

Call of Duty: Black Ops: Declassified
Red Dot Sight is seen on various weapons in Gamescom trailer.

Call of Duty: Modern Warfare: Mobilized

 * All Red Dot Sights in Modern Warfare: Mobilized are misaligned, the true hit point being slightly higher than the dot itself.

Call of Duty: Modern Warfare 2

 * In Call of Duty: Modern Warfare 2, the zoom of the RDS (and other optics) varies by weapon in singleplayer, but is the same for all weapons in multiplayer.
 * The FAL's and M93 Raffica's red dot sights are mis-calibrated. The shots land below and to the right of the dot.
 * The SCAR-H has a unique beige red dot sight.

Call of Duty: Black Ops

 * The RPK, AK-47, and AK74u use a different, bigger and less rounded Red Dot Sight of Soviet origin.
 * On the Wii version of the game, the color reticle can't be changed.