How Do Autofocus Binoculars Work?

What Are Autofocus Binoculars?

An AutoFocus Binocular is a specifically designed binocular that is permanently focused.

These binoculars are designed by makers from the outset to permanently focus on objects located at medium distances of anywhere between 30 to 60 feet to longer distances.

Also referred to as self-focusing, constant-focus binoculars help you to get a clear view of objects whenever you peek through them without the need to strain the eye or using your fingers to adjust the binocular focus.

Since there is no adjustment involved the only adjustment to be done is with your eyesight to stop it from straining.

There are 2 types of autofocus binoculars for you to choose from, the first type is a rigid design that gives you no option to adjust the binocular’s barrels.

The second type is a more flexible design that allows you to change the focus of binocular barrels separately. While the first type strains your eyesight, the second design gives you a significantly better view.

The biggest players in the market that supply the autofocus binoculars are Celestron, Bushnell, Orion, Steiner, and Barska.

When and Why Do You Need an Autofocus Binocular?

You can use this type of binoculars to watch a live game of cricket or football or horse/bike race without straining the eyes.

Ideally suited for situations when it is not necessary to watch for a long period of time through binoculars. 

An affordable, lightweight, very easy to use autofocus binocular comes with a provision to adjust for one or both eyes, is ideally suited for use when you don’t want to spend money on buying professional high focus/ magnification binoculars.

Also called fixed focus binoculars, these binoculars allow you to watch objects over long distances for a wide-angle general view but you can’t use it for a detailed closer look akin to birdwatching.

This is ideally suited for you if you have weak eyesight. You may be nearsighted or farsighted or astigmatic.

The condition of your eyesight affects the way you see things using autofocus binoculars.

Do Autofocus Binoculars Focus Automatically?

No, frankly speaking, autofocus binoculars do not have the ability to inherently perform automatic or self-focus.

The no focus mechanism in use makes it more of a focus-free or fixed focus binoculars. Basically, this means these binoculars work only that much better as much your eyesight‘s ability to naturally focus on distant objects.

As such to make up for the shortcomings these binoculars in general use more than one diopter (one for each eye) that can be adjusted accordingly.

This diopter adjustment allows you to attune your binoculars to your eyesight and helps you see better what your eyes see.

This means that these binoculars help build on the image, the crystalline lens of the human eye creates on the eye’s retina.

Working Mechanism of Autofocus Binoculars

Autofocus or fixed focus binoculars work on the same principle as any other types of binoculars.

What sets them apart is that they are always fixed at a particular distance to focus with a wide-angle field of view.

Autofocus binoculars have objective lenses that receive light from the object that you are viewing and it is passed to an eyepiece lens to create a better image for your viewing as if from close quarters.

The working mechanism of autofocus binoculars is simple. All you need to do is to adjust the focus till the binocular is at its extreme distant focus and then look at a distant object by closing your right eye.

Then slowly bring the binocular focus back until the object you want to view is visible to your eye in sharp focus.

Repeat the process until the image you want to view is absolutely clear in the binocular. Once you get that, don’t touch the center-focus knob again.

Once the binocular is fixed in the left eye, the next step is to do a diopter adjustment to ensure you can see through the binocular using your right eye.

This can be done by adjusting the ring just forward of the right eyepiece.

However, sometimes this ring is found on the left eyepiece or as a separate knob that you will have to pull out from the center-focus knob.

Then repeat the process to adjust the focus on the right-side eyepiece with your left eye closed, as you did earlier while adjusting the left side eyepiece.

Adjust the focus till the binocular is at its extreme distant focus and then look at a distant object by closing your left eye.

Then slowly bring the binocular focus back until the object you want to view is visible to your eye in sharp focus. Repeat the process until the image is absolutely clear.

If you can “lock” the adjustment for the right eyepiece, do it. Locking a diopter ring pushes it away from the eyepiece.

How Autofocus Binoculars are Designed

The autofocus binoculars come in four different sizes namely compact, mid-size, full-size, and dual power, and two different types of autofocus designs.

In the first type, there is no option to adjust the binoculars, also called center-focused binoculars.

In the second type you have the option to adjust the two barres separately, hence also called individual focus binoculars. 

These binoculars are affordable, lightweight, easy to use, and highly adaptable to different user requirements.

Most auto-focus binoculars have two separate diopters in eyepiece/barrel, one for each eye. The most common type of autofocus binoculars is a prism binocular that make use of convex lenses for use in both the eyepiece.

The objective lens then creates a prism system that is incorporated into your eye’s optical path. The inverted image is then rectified through an objective lens and you get to see the intended object. 

Designed for observing objects that are moving fast or while you are moving there are ideal for use both in the winter, rainy as well as in summer season.

Advantages

The autofocus binoculars have several advantages and few disadvantages, such as: –

• These are ideally suited for users who need to wear corrective eyewear due to sight issues and those who are of old age.
• Autofocus binoculars have fewer moving parts that make it easy to clean them and keep them dustproof.
• Ideally suited to view fast-moving objects or if the user itself is moving fast.
• Ideally suited for viewing objects with a deep and wide-angle field of view.
• These binoculars have fewer moving parts that make them lighter and much less complicated than other types.
• Ideal for use by kids.
• Convenient to hold with just one hand

Disadvantages

• Once you adjust the autofocus binoculars according to your personal eyesight requirement you can’t share it with other people.
• Doesn’t support detailed viewing efforts.
• These binoculars are not meant for viewing at a close range.
• The use is limited to fast-paced wide-angle view only, any attempt to have a detailed view requires a different binocular.

Conclusion

Auto-focus binoculars are just for you if you are looking for a binocular that is hassle-free, compact, and doesn’t require too much maintenance to work.

It is ideally suited for people who have eyesight problems and don’t want to strain their eyes to watch something they love to watch live.

You can opt for a center-focus or independent focus variety as per your preference.

Celestron, Orion, Steiner Bushnell, and Barska are the biggest players in the autofocus binocular market and are leading suppliers of binocular accessories as well.

Also referred to as single-user binoculars, these are easy to handle and thus ideally suited for use by kids. 

The word autofocus is predominantly used as a marketing tool for selling these binoculars as the word fixed focus binoculars are more aptly suited for these types of binocular.

It is up to the user, which type of autofocus binocular, he or she wants to buy based on the requirement.

Since these binoculars are evenly priced, they are not too heavy on the pocket, and anyone who is interested in watching an event unfold from a distance can buy these binoculars.