Riflescopes

Optical or thermal: choose how you want to see the scene

An optical riflescope is a magnifying sight. Light from the scene passes through the objective lens, the magnification system and the eyepiece. You see the scene directly, with a reticle placed over it. The view depends on the light available.

A thermal riflescope works differently. Its sensor detects infrared radiation given off by objects and shows differences in that signal as contrast in an electronic image. The contrast reflects the infrared signal reaching the sensor, not a direct map of temperature. Because it does not rely on visible light to form the picture, the view looks quite unlike an optical one.

Digital night-vision scopes use a third approach. A sensor that responds to visible and near-infrared light produces the image, so these scopes need some available light or an infrared illuminator. If you want this technology, browse the dedicated night vision collection. For scopes that work across more than one part of the spectrum, see multispectral riflescopes. The thermal riflescopes collection lists thermal models without the optical scopes shown here.

Reading optical riflescope model names

Most optical riflescope names include a short notation. Take 3-9x40 as an example. The 3-9 is the variable magnification range, so the view can be set anywhere from three to nine times. The 40 is the diameter of the objective (front) lens in millimetres. A fixed-magnification scope has a single number before the x instead of a range.

When comparing scopes of similar design, a larger objective lens collects more light but usually adds size and weight. A wider magnification range gives more flexibility across different viewing distances. Neither number tells you anything about the quality of the glass or the build. Other letters in a model name are usually the manufacturer's own shorthand, so check the product specification to see what they mean on that model. Some optical model names include letters such as NV. Go by the listed specification, not the name, to find out which technology a scope uses.

Magnification, field of view and handling

Field of view is the width of the scene you can see through the scope. It is usually given either as an angle or as a width at a stated distance. On a variable optical scope, the field of view narrows as magnification increases. Low settings show more of the surroundings, while higher settings show more detail across a smaller area.

When comparing models, consider how much of the scene you usually want to see and how much enlargement you need. Then compare the published magnification ranges and field-of-view figures side by side, using the same units. Two scopes with the same magnification can still have different fields of view because of their optical design. A bigger zoom range does not automatically make a better scope, and any extra length and weight will affect how the rifle handles.

Eye relief, size and fit

Eye relief is the distance between the eyepiece and your eye at which you can see the full field of view.

Before choosing, check the eye relief, overall length, weight and tube diameter for the exact model. Compare these with your rifle and with any mounts or rings you own or plan to buy. Compatibility depends partly on tube diameter and on the manufacturer's guidance for that model. Check those details on each product page; one size does not suit every scope.

First or second focal plane reticles

On a variable optical riflescope, the reticle sits in either the first focal plane (FFP) or the second focal plane (SFP). You can see the difference when you change magnification. An FFP reticle appears to grow and shrink as you zoom, so it stays in proportion with the scene. It can look finer at low magnification and bolder at high magnification. An SFP reticle looks the same size at every magnification while the scene around it is enlarged or reduced.

Neither type suits everyone. Choose an FFP riflescope if you want reticle markings that stay in proportion with the view. Choose an SFP riflescope if you prefer a reticle that always looks the same. Check the product title or specification of the variable optical riflescope for the focal plane.

Riflescope questions

What does a number such as 3-9x40 mean?

On an ordinary optical riflescope, 3-9 is the magnification range, so the view adjusts from 3x to 9x, and 40 is the objective lens diameter in millimetres. Thermal model names do not always follow this notation, so check the listed specification for each thermal model.

Does higher magnification always mean a better riflescope?

No. Higher magnification enlarges the view, but it also narrows the field of view and can mean a longer, heavier scope. Choose a range that matches how much of the scene you want to see and how much detail you need. Compare field-of-view figures alongside magnification.

What is the difference between FFP and SFP?

On variable optical riflescopes, the difference is in how the reticle looks as you zoom. An FFP reticle changes apparent size with magnification and stays in proportion with the scene. An SFP reticle stays the same apparent size while the scene changes. Check the focal plane in the riflescope's specification and choose the behaviour you prefer.

What should I check for eye relief and fit?

Compare the stated eye relief, length, weight and tube diameter for the exact model. Then confirm compatibility with your mounts or rings using the manufacturer's information. Sizes vary between models, so do not assume one set of rings or one eye-relief figure applies to the whole range.

Does an illuminated reticle mean a scope has night vision?

No. An illuminated reticle lights up the reticle lines so they stand out against the view. It does not brighten the surroundings or create a night-vision image, so the optical view still depends on the light available. Digital night-vision and thermal devices use different ways of forming an image.

Are thermal scopes and digital night-vision scopes the same?

No. A thermal scope builds its image from differences in infrared radiation given off by objects, so it does not depend on visible light. A digital night-vision scope uses a sensor that responds to visible and near-infrared light, so it needs some available light or an infrared illuminator. You will find thermal models in this collection and in the dedicated thermal riflescopes category. For digital night-vision scopes, browse the night vision collection.