Accurate Shooter Forum Members:
We are continuing discussion of Riflescope Basics (started back in July). Sorry for taking this long, but just like many of you here - jobs and demands of the "real" world have kept us busy. Special thanks go out to Ilya from OpticsThoughts for collaborating on this project.
NON FOCUSING SIGHTS
So far, all the riflescopes I mention are "focusing" optical instruments. What that means, is that the scope re-creates an image of the object in front of it a certain distance behind the riflescope. That distance is called "eye relief", and it is typically between three and four inches (75 to 100mm). In order to see the image presented by the scope, your eye has to be in a specific spot behind the riflescope. There is some leeway to the eye position, of course, but if you happen to place your eye too far off, you won't see much.
Non-focusing sights are the ones that do not have that eye positioning limitation, but they also do not offer any magnification. These are non-magnifying sights that include various red-dot and holographic sights. There are couple of 1x (unity magnification) focusing scope out there (Leupold Prismatic) for example. They have pretty flexible eye position requirements, but they are still not quite as lenient in that regard as true non-focusing sights.
Red-dot and holographic sights are designed for super-fast target acquisition with both eyes open and work well for close-range tactical applications. These are the sights your most frequently see in pictures from Iraq and Afghanistan mounted on the army issued M4 carbines. US military issues a large number of Aimpoint red-dot sights and Eotech holographic sights. They represent the two most common types of non-focusing sights out there.
Here is a picture of an Aimpoint:
Effectively, all you are trying to do with a sight like this is look through a short tube that makes up is body. If your eye is positioned along a straight line behind the sight (or close enough to it), you'll see a red dot, which is your aiming point. In order to have reasonably fast target acquisition, the dot is pretty large (although this varies between models). Unfortunately, a large dot that aids target acquisition also makes it harder to shoot accurately at longer ranges. Still, a red dot sight is easily good enough to shoot deer-size targets within 100yards, and, in the hands of a skilled shooter, a fair bit further than that.
Here is what the latest Eotech looks like:
Aiming with the Eotech, in principle, is similar to aiming with the Aimpoint: look through the squarish tube and place the reticle onto your target. However, the reticle of the Eotech is a circle-dot arrangement, rather than a large dot of the Aimpoint:
With the Eotech, you are looking through a holographic screen and, in some circumstances, the reticle can appear pixelated which some people find distracting. However, on balance, both Aimpoint's large dot and Eotech's circle-dot are very effective.
In recent years, in order to extend long range capabilities of red-dot sights, a few companies introduced magnifiers. These are essentially short monoculars with 3x or 4x magnifications that can be placed immediately behind a red-dot sight. When not in use, they can be either removed or flipped aside.
Lastly, there is quite a number of so-called "micro red-dot sights" on the market. These are simply red-dots small enough to be mounted on handguns or as secondary sight onto riflescopes. Aside from tiny size, their operation is not different from any other red-dot sight.
We are continuing discussion of Riflescope Basics (started back in July). Sorry for taking this long, but just like many of you here - jobs and demands of the "real" world have kept us busy. Special thanks go out to Ilya from OpticsThoughts for collaborating on this project.
NON FOCUSING SIGHTS
So far, all the riflescopes I mention are "focusing" optical instruments. What that means, is that the scope re-creates an image of the object in front of it a certain distance behind the riflescope. That distance is called "eye relief", and it is typically between three and four inches (75 to 100mm). In order to see the image presented by the scope, your eye has to be in a specific spot behind the riflescope. There is some leeway to the eye position, of course, but if you happen to place your eye too far off, you won't see much.
Non-focusing sights are the ones that do not have that eye positioning limitation, but they also do not offer any magnification. These are non-magnifying sights that include various red-dot and holographic sights. There are couple of 1x (unity magnification) focusing scope out there (Leupold Prismatic) for example. They have pretty flexible eye position requirements, but they are still not quite as lenient in that regard as true non-focusing sights.
Red-dot and holographic sights are designed for super-fast target acquisition with both eyes open and work well for close-range tactical applications. These are the sights your most frequently see in pictures from Iraq and Afghanistan mounted on the army issued M4 carbines. US military issues a large number of Aimpoint red-dot sights and Eotech holographic sights. They represent the two most common types of non-focusing sights out there.
Here is a picture of an Aimpoint:
Effectively, all you are trying to do with a sight like this is look through a short tube that makes up is body. If your eye is positioned along a straight line behind the sight (or close enough to it), you'll see a red dot, which is your aiming point. In order to have reasonably fast target acquisition, the dot is pretty large (although this varies between models). Unfortunately, a large dot that aids target acquisition also makes it harder to shoot accurately at longer ranges. Still, a red dot sight is easily good enough to shoot deer-size targets within 100yards, and, in the hands of a skilled shooter, a fair bit further than that.
Here is what the latest Eotech looks like:
Aiming with the Eotech, in principle, is similar to aiming with the Aimpoint: look through the squarish tube and place the reticle onto your target. However, the reticle of the Eotech is a circle-dot arrangement, rather than a large dot of the Aimpoint:
With the Eotech, you are looking through a holographic screen and, in some circumstances, the reticle can appear pixelated which some people find distracting. However, on balance, both Aimpoint's large dot and Eotech's circle-dot are very effective.
In recent years, in order to extend long range capabilities of red-dot sights, a few companies introduced magnifiers. These are essentially short monoculars with 3x or 4x magnifications that can be placed immediately behind a red-dot sight. When not in use, they can be either removed or flipped aside.
Lastly, there is quite a number of so-called "micro red-dot sights" on the market. These are simply red-dots small enough to be mounted on handguns or as secondary sight onto riflescopes. Aside from tiny size, their operation is not different from any other red-dot sight.
